Tuesday, November 6, 2007

Top 10 Ugliest Animals

10. Mata Mata

The mata mata is a freshwater turtle found predominantly in South America, notably in the Amazon and Orinoco basins. The animal’s peculiar physical aspect distinguishes it from other members of its order. It is an animal highly skilled in hunting techniques.


9. Horseshoe Bat

Horseshoe bats (the Rhinolophidae family) are a large family of bats including approximately 130 species grouped in 10 genera. All rhinolophids have leaf-like protuberances on their noses. In rhinolophines species, these take the shape of a horseshoe; in hipposiderine, they are leaf- or spear-like. They emit echolocation calls through these structures, which may serve to focus the sound. Most rhinolophids are dull brown or reddish brown in color. They vary in size from small to moderately large.



8. Star Nosed Mole

The Star-nosed Mole is a small North American mole found in eastern Canada and the north-eastern United States. It lives in wet lowland areas and eats small invertebrates, aquatic insects, worms and molluscs. It is a good swimmer and can forage along the bottoms of streams and ponds. Like other moles, this animal digs shallow surface tunnels for foraging; often, these tunnels exit underwater. It is active day and night and remains active in winter, when it has been observed tunnelling through the snow and swimming in ice-covered streams.


7. Sloth

Sloths are medium-sized mammals that live in Central and South America. Sloths are omnivores. They may eat insects, small lizards and carrion, but their diet consists mostly of buds, tender shoots, and leaves. Sloth fur also exhibits specialized functions: the outer hairs grow in a direction opposite from that of other mammals. In most mammals, hairs grow toward the extremities, but because sloths spend so much time with their legs above their bodies, their hairs grow away from the extremities in order to provide protection from the elements while the sloth hangs upside down.



6. Naked Mole Rat

The Naked Mole Rat, also known as the Sand Puppy, or Desert Mole Rat, is a burrowing rodent native to parts of East Africa. Typical individuals are 8–10 cm long and weigh 30–35 g. Queens are larger and may weigh well over 50 g, the largest reaching 80 g. They are well-adapted for their underground existence. Their eyes are just narrow slits, and consequently their eyesight is poor. However, they are highly adapted to moving underground, and can move backwards as fast as they move forwards. Their large, protruding teeth are used to dig. Their lips are sealed just behind their teeth while digging to avoid filling their mouths with soil. Their legs are thin and short. They have little hair (hence the common name) and wrinkled pink or yellowish skin.


5. Axolotl

The Axolotl (or ajolote) is the best-known of the Mexican neotenic mole salamanders belonging to the Tiger Salamander complex. Larvae of this species fail to undergo metamorphosis, so the adults remain aquatic and gilled. Their heads are wide, and their eyes are lidless. Their limbs are underdeveloped and possess long, thin digits. Axolotls have barely visible vestigial teeth which would have developed during metamorphosis. The primary method of feeding is by suction, during which their rakers interlock to close the gill slits. Axolotls have 4 different colours, 2 naturally occurring colours and 2 mutants. The 2 naturally occurring colours are wildtype (Varying shades of brown usually with spots) and melanoid (black). The 2 mutants colours are leucistic (pale pink with black eyes) and albino (golden, tan or pale pink with pink eyes).


4. Tarsier

Tarsiers are prosimian primates of the genus Tarsius. Tarsiers have enormous eyes and long feet. Their feet have extremely elongated tarsus bones, which is how they got their name. They are primarily insectivorous, and catch insects by jumping at them. They are also known to prey on birds and snakes. As they jump from tree to tree, tarsiers can catch even birds in motion. Tarsiers have never formed successful breeding colonies in captivity, and when caged, tarsiers have been known to injure and even kill themselves because of the stress.


3. Hagfish

Despite their name, there is some debate about whether Hagfish are strictly fish, since they belong to a much more primitive lineage than any other group that is commonly defined fish. Hagfish are long, vermiform and can exude copious quantities of a sticky slime or mucus. When captured and held by the tail, they escape by secreting the fibrous slime, which turns into a thick and sticky gel when combined with water, and then cleaning off by tying themselves in an overhand knot which works its way from the head to the tail of the animal, scraping off the slime as it goes. Hagfish have elongated, ‘eel-like’ bodies, and paddle-like tails.


2. Aye-aye

The Aye-aye is a native to Madagascar that combines rodent-like teeth with a long, thin middle finger to fill the same ecological niche as a woodpecker. The Aye-aye is the world’s largest nocturnal primate, and dwells predominantly in forest canopies. The adult Aye-aye has black or dark brown fur covered by white guard hairs at the neck. The tail is bushy and shaped like that of a squirrel. The Aye-aye’s face is also rodent-like, the shape of a raccoon’s, and houses bright, beady, luminous eyes. Its incisors are very large, and grow continuously throughout its lifespan.


1. Blobfish

The Blobfish inhabits the deep waters off the coasts of Australia and Tasmania. Due to the inaccessibility of its habitat, it’s rarely seen by humans. Blobfish are found at depths where the pressure is several dozens of times higher than at sea level. To remain buoyant, the flesh of the Blobfish is primarily a gelatinous mass with a density slightly less than water; which allows the fish to float above the sea floor without expending energy on swimming. The relative lack of muscle is not a disadvantage as it primarily swallows edible matter that floats by in front it.

Friday, November 2, 2007

Top 10 Strangest Animals

10. Frill-necked Lizard

The Frill-necked Lizard, also known as the Frilled Dragon, is so called because of the large ruff of skin which usually lies folded back against its head and neck. Long spines of cartilage support the neck frill, and when the lizard is frightened, it opens its mouth showing a bright pink or yellow lining, and the frill flares out, displaying bright orange and red scales. They often walk on four legs when on the ground. When frightened they begin to run on all fours and then accelerate onto the hind-legs. The frill of the Australian frilled dragon is used to frighten off potential predators, as well as hissing and lunging.


9. Dumbo Octopus

The octopuses of the genus Grimpoteuthis are also known as “Dumbo octopuses” from the ear-like fins protruding from the top of their “heads” (actually bodies), resembling the ears of Walt Disney’s flying elephant. They are benthic creatures, living at extreme depths, and are some of the rarest of the Octopoda species. They can flush the transparent layer of their skin at will, and are open ocean animals, unlike most octopi.


8. Angora Rabbit

The Angora rabbit is a variety of domestic rabbit bred for its long, soft hair. The rabbits were popular pets with French royalty in the mid 1700s, and spread to other parts of Europe by the end of the century. They are bred largely for their long wool, which may be removed by shearing or plucking (gently pulling loose wool).



7. Tasmanian Tiger

The Thylacine was the largest known carniv

orous marsupial of modern times. Native to Australia and New Guinea, it is thought to have become extinct in the 20th century. It is commonly known as the Tasmanian Tiger (due to its striped back), the Tasmanian Wolf, and colloquially the Tassie (or Tazzy) Tiger. It was the last extant member of its genus, Thylacinus, although a number of related species have been found in the fossil record dating back to the early Miocene. The Thylacine became extinct on the Australian mainland thousands of years before European settlement of the continent, but survived on the island of Tasmania along with a number of other endemic species, including the Tasmanian Devil. Intensive hunting encouraged by bounties is generally blamed for its extinction, but other contributory factors may have been disease, the introduction of dogs, and human encroachment into its habitat. Despite being officially classified as extinct, sightings are still reported.


6. Platypus

The Platypus is a semi-aquatic mammal endemic to eastern Australia. Together with the four species of echidna, it is one of the five mammals that lay eggs instead of giving birth to live young. The bizarre appearance of this egg-laying, duck-billed mammal baffled naturalists when it was first discovered, with some considering it an elaborate fraud. It is one of the few venomous mammals; the male Platypus has a spur on the hind foot, which delivers a poison capable of causing severe pain to humans. The unique features of the Platypus make it an important subject in the study of evolutionary biology and a recognizable and iconic symbol of Australia; it has appeared as a mascot at national events and is featured on the reverse of the Australian 20 cent coin.


5. Narwhal

The Narwhal is an Arctic species of cetacean. It is one of two species of white whale, the other being the Beluga whale. The most conspicuous characteristic of male narwhal is their single extraordinarily long tusk, an incisor that projects from the left side of the upper jaw and forms a left-handed helix. The tusk can be up to nearly 10 feet long and weigh up to 22 pounds. About one in 500 males has two tusks, which occurs when the right tooth, normally small, also grows out. The purpose of the tusk has been the subject of much debate. Early scientific theories suggested that the tusk was used to pierce the ice covering the narwhal’s Arctic Sea habitat. Others suggested the tusk was used in echolocation. More recently, scientists believed the tusk is primarily used for showmanship and for dominance: males with larger tusks are more likely to successfully attract a mate.


4. Anglerfish

Anglerfish are named for their characteristic mode of perdition, wherein a fleshy growth from the fish’s head (the esca) acts as a lure. Anglerfish also have spines protruding from their head, movable in all directions. The esca can be wiggled so as to resemble a prey animal, and thus to act as bait to lure other predators. Deep-sea anglerfish live mainly in the oceans’ aphotic zones, where the water is to deep for the sun to penetrate; therefore their perdition relies on the “lure” being bioluminescent. Since individuals are presumably locally rare and encounters doubly so, finding a mate is problematic. When scientists first started capturing ceratioid anglerfish, they noticed that all of the specimens were females. These individuals were a few inches in size and almost all of them had what appeared to be parasites attached to them. It turned out that these “parasites” were the remains of male ceratioids


3. Leafy Sea-dragon

Named after the dragons of Chinese mythology, Leafy Sea-dragons resemble a piece of drifting seaweed as they float in the seaweed-filled water. The Leafy Sea-dragon, with green, orange and gold hues along its body, is covered with leaf-like appendages, making it remarkably camouflaged. Only the fluttering of tiny fins or the moving of an independently swiveling eye reveals its presence. Sea-dragons have no teeth or stomach and feed exclusively on mysidopsis shrimp. Known as “Australian seahorses” in Australia, they are found in calm, cold water that is approximately 50-54° Fahrenheit. The South Australian government since 1982 has protected Leafy Sea-dragons.


2. Yeti Crab

Kiwa hirsuta is a crustacean discovered in 2005 in the South Pacific Ocean. This decapod, 6 inches long, is notable for the quantity of silky blond setae (resembling fur) covering thoracic legs and claws. Its discoverers dubbed it the “yeti lobster” or “yeti crab”. Based on both morphology and molecular data, the species was deemed to form a new genus and family (Kiwaidae). The animal has strongly reduced eyes that lack pigment, and is thought to be blind. The ‘hairy’ pincers contain filamentous bacteria, which the creature may use to detoxify poisonous minerals from the water emitted by the hydrothermal vents where it lives. Alternatively, it may feed on the bacteria, although it is thought to be a general carnivore. Its diet also consists of green algae and small shrimp.


1. Coelacanth

Coelacanth is the common name for an order of fish that includes the oldest living lineage of jawed fish known to date. The coelacanths, which are related to lungfishes and tetrapods, were believed to have been extinct since the end of the Cretaceous period, until the first specimen was found off the east coast of South Africa, off the Chalumna River in 1938. Since 1938, they have been found in the Comoros, Kenya, Tanzania, Mozambique, Madagascar, among other places. Coelacanths first appear in the fossil record in the Middle Devonian, about 410 million years ago. Coelacanths are lobe-finned fish with the pectoral and anal fins on fleshy stalks supported by bones, and the tail or caudal fin diphycercal (divided into three lobes), the middle one of which also includes a continuation of the notochord.

Wednesday, October 10, 2007

The Living Dinosaur

Komodo dragons are the world's heaviest living lizards. They can grow to a length of 10 feet (over 3 meters), with an average length of 8 feet (2.5 meters) and weight of 200 lbs (91 kg.). Females are usually under 8 feet and weigh about 150 lbs. (68 kg.).

The Komodo dragon's keen sense of smell, if aided by favorable wind, enables it to seek out carrion. up to 5 miles (8.5 kilometers) away. Despite its size, the Komodo is fast moving and agile. They can climb trees and like all monitor lizards they are good swimmers.

Their teeth are laterally compressed with serrated edges, resembling those of flesh-eating sharks. They have about 60 teeth that they replace frequently and are positioned to cut out chunks of its prey. The highly flexible skull allows it to swallow large pieces of its food. The Komodos mouth is full of virulent bacteria and even if its prey survives the original attack, it will die of infection later.

Young dragons up to 29 inches (.75 meters) live in trees and eat insects, birds, eggs, small mammals and other reptiles. They will descend from the tree for carrion.

DISTRIBUTION and HABITAT:

The distribution of Komodo dragons is restricted to the Lesser Sunda Islands of Rinca, Komodo, Flores and the smaller islands of Gili, Montang and Padar. Padar does not have a permanent population. The total range is less than 1,000 sq. km. Komodo National Park makes up all islands except Flores.

The natural habitat of Komodo dragons is extremely harsh by human standards. These arid volcanic islands have steep slopes and little available water most of the year. A short monsoon season often produces local flooding. The average annual temperature at sea level on Komodo island is 80F. degrees. Dragons are most abundant in the lower arid forest and savanna.

Outsiders found out about the Komodo dragons after WW1 when a report came from a downed aircraft and the surviving pilot swam to Komodo Island.

BEHAVIOR:

In the wild, Komodo dragons are generally solitary animals, except during the breeding season. Males maintain and defend a territory and patrol up to 1.2 miles (2 km.) per day. Territories are dependent on the size of the dragon. Feeding ranges extend further and may be shared with other males. A dragon will allow other dragons to cross its territory when they are on a food run.

Dragons maintain burrows within their core ranges and occasionally males will swim from island to island over long distances. They regulate their body temperature (thermoregulation) by using a burrow.

DIET:

The Komodo is carnivorous and cannibalistic and it has a prodigious appetite. They regularly kill prey as large as pigs and small deer, and have been known to bring down an adult water buffalo. They are opportunistic feeders and will eat anything they can overpower including small dragons and small or injured humans (dragons make up to 10% of their diet).

An eyewitness account revealed that a 101 lb (46 kg.) dragon ate a 90 lb. (41 kg.) pig in 20 minutes. As a comparison, a 100 lb. person would have to eat 320 quarter pound hamburgers in less than 20 minutes to keep up with the dragon.

In the zoo, the Komodo dragons are fed previously frozen rats.

REPRODUCTION and GROWTH:

The life expectancy of a Komodo is between 20 to 40 years. As noted above, Komodo dragons are generally solitary animals, except during the breeding season.

The male Komodo dragon presses his snout to the female's body, and flicks her with his long, forked tongue to obtain chemical information about her receptivity. He then scratches her back with his long claws, making a ratchet-like noise. If unreceptive, she raises and inflates her neck and hisses loudly.

The female wild dragons will utilize the nest mound of a brush turkey in which she will lay a clutch of up to 30 eggs. Hatchlings are about 15 inches (40 centimeters) and weigh 3.5 ounces (100g.).

Juveniles are multi-hued, (yellow, green, brown and gray); with a speckled and banded skin. Adult colors vary from earthen red to slate gray and black.

STATUS:

Endangered: The largest threat is volcanic activity, fire and subsequent loss of its prey base. Currently habitat alteration , poaching of prey species and tourism may have the most pronounced effect. Commercial trade in specimens or skins is illegal under the Convention on International Trade in Endangered Species (CITES).

Wild Population: 3,000 to 5,000.

The Land Giant

The word "elephant" has its origins in the Greek λέφας, meaning "ivory" or "elephant".

Elephants are mammals, and the largest land animals alive today. The elephant's gestation period is 22 months, the longest of any land animal. At birth it is common for an elephant calf to weigh 120 kilograms (265 lb). An elephant may live as long as 70 years, sometimes longer. The largest elephant ever recorded was shot in Angola in 1956. This male weighed about 12,000 kg (26,400 lb), with a shoulder height of 4.2 m (13.8 ft), a metre (3 ft 4 in) taller than the average male African elephant. The smallest elephants, about the size of a calf or a large pig, were a prehistoric species that lived on the island of Crete during the Pleistocene epoch.

Elephants are symbols of wisdom in Asian cultures, and are famed for their exceptional memory and very high intelligence, on par with cetaceans and hominids. Aristotle once said the elephant was "the beast which passeth all others in wit and mind."

Elephants are increasingly threatened by human intrusion and poaching. Once numbering in the millions, the African elephant population has dwindled to between 470,000 and 690,000 individuals. The elephant is now a protected species worldwide, with restrictions in place on capture, domestic use, and trade in products such as ivory. Elephants generally have no natural predators, although lions may take calves and occasionally adults. In some areas, lions may regularly take to preying on elephants.

African Elephant

The Elephants of the genus Loxodonta, known collectively as African elephants, are currently found in 37 countries in Africa.

African elephants are distinguished from Asian elephants in several ways, the most noticeable being their ears. Africans' ears are much larger and are shaped – some note – like the continent of their origin. The African is typically larger than the Asian and has a concave back. Both African males and females have external tusks and are usually less hairy than their Asian cousins.

African elephants have traditionally been classified as a single species comprising two distinct subspecies, namely the savanna elephant (Loxodonta africana africana) and the forest elephant (Loxodonta africana cyclotis), but recent DNA analysis suggests that these may actually constitute distinct species. While this split is not universally accepted by experts a third species of African elephant has also been proposed. Under the new two species classification, Loxodonta africana refers specifically to the Savanna Elephant, the largest of all elephants. In fact, it is the largest land animal in the world, standing up to 4 m (13 ft) at the shoulder and weighing approximately 7,000 kg (7.7 tons). The average male stands about 3 m (10 ft) tall at the shoulder and weighs about 5500–6000 kg (6.1–6.6 tons), the female being much smaller. Most often, Savanna Elephants are found in open grasslands, marshes, and lakeshores. They range over much of the savanna zone south of the Sahara.

The other postulated species is the Forest Elephant (Loxodonta cyclotis). Compared with the Savanna Elephant, its ears are usually smaller and rounder, and its tusks thinner and straighter and not directed outwards as much. The Forest Elephant can weigh up to 4,500 kg (10,000 lb) and stand about 3 m (10 ft) tall. Much less is known about these animals than their savanna cousins because environmental and political obstacles make them very difficult to study. Normally, they inhabit the dense African rain forests of central and western Africa, though occasionally they roam the edges of forests and so overlap the territories of the Savanna elephants and breed with them. In 1979, Iain Douglas-Hamilton estimated the continental population of African elephants at around 1.3 million animals. This estimate is controversial and is believed to be a gross overestimate, but it is very widely cited and has become a de facto baseline that continues to be incorrectly used to quantify downward population trends in the species. Through the 1980s, Loxodonta received worldwide attention due to the dwindling numbers of major populations in East Africa, largely as a result of poaching. Today, according to IUCN’s African Elephant Status Report 2007 there are approximately between 470,000 and 690,000 African elephants in the wild. Although this estimate only covers about half of the total elephant range, experts do not believe the true figure to be much higher, as it is unlikely that large populations remain to be discovered. By far the largest populations are now found in Southern and Eastern Africa, which together account for the majority of the continental population. According to a recent analysis by IUCN experts, most major populations in Eastern and Southern Africa are stable or have been steadily increasing since the mid-1990s, at an average rate of 4.5% per annum. Elephant populations in West Africa, on the other hand, are generally small and fragmented, and only account for a small proportion of the continental total. Much uncertainty remains as to the size of the elephant population in Central Africa, where the prevalence of forest makes population surveys logistically difficult, but poaching for ivory and bushmeat is believed to be intense through much of the region.

Asian Elephant

The Asian elephant is smaller than the African. It has smaller ears, and typically, only the males have large external tusks.

The world population of Asian elephants – also called Indian Elephants or Elephas maximus – is estimated to be around 60,000, about a tenth of the number of African elephants. More precisely, it is estimated that there are between 38,000 and 53,000 wild elephants and between 14,500 and 15,300 domesticated elephants in Asia with perhaps another 1,000 scattered around zoos in the rest of the world. The Asian elephants' decline has possibly been more gradual with the causes primarily being poaching and habitat destruction by human encroachment.

There are several subspecies of Elephas maximus and some have been identified only using molecular markers. The first subspecies is the Sri Lankan Elephant (Elephas maximus maximus). Found only on the island of Sri Lanka, it is the largest of the Asians. There are only an estimated 3,000–4,500 members of this subspecies left today in the wild, although no accurate census has been carried out in the recent past. Large males can weigh upward to 5,400 kg (12,000 lb) and stand over 3.4 m (11 ft) tall. Sri Lankan males have very large cranial bulges, and both sexes have more areas of depigmentation than are found in the other Asians. Typically, their ears, face, trunk, and belly have large concentrations of pink-speckled skin. There is an orphanage for elephants in Pinnawala Sri Lanka, which gives shelter to disabled, injured elephants. This program plays a large role in protecting the Sri Lankan Elephant from extinction.

Another subspecies, the Indian Elephant (Elephas maximus indicus) makes up the bulk of the Asian elephant population. Numbering approximately 36,000, these elephants are lighter grey in colour, with depigmentation only on the ears and trunk. Large males will ordinarily weigh only about 5,000 kg (11,000 lb) but are as tall as the Sri Lankan. The mainland Asian can be found in 11 Asian countries, from India to Indonesia. They prefer forested areas and transitional zones, between forests and grasslands, where greater food variety is available.

The smallest of all the elephants is the Sumatran Elephant (Elephas maximus sumatranus). Population estimates for this group range from 2,100 to 3,000 individuals. It is very light grey and has less depigmentation than the other Asians, with pink spots only on the ears. Mature Sumatrans will usually only measure 1.7–2.6 m (5.6–8.5 ft) at the shoulder and weigh less than 3,000 kg (6,600 lb). An enormous animal nonetheless, it is considerably smaller than its other Asian (and African) cousins and exists only on the island of Sumatra, usually in forested regions and partially wooded habitats.

In 2003 a further subspecies was identified on Borneo. Named the Borneo pygmy elephant, it is smaller and tamer than other Asian elephants. It also has relatively larger ears, longer tail and straighter tusks.

Body characteristics

Trunk

The proboscis, or trunk, is a fusion of the nose and upper lip, elongated and specialized to become the elephant's most important and versatile appendage. African elephants are equipped with two fingerlike projections at the tip of their trunk, while Asians have only one. According to biologists, the elephant's trunk may have over forty thousand individual muscles in it, making it sensitive enough to pick up a single blade of grass, yet strong enough to rip the branches off a tree. Some sources indicate that the correct number of muscles in an elephant's trunk is closer to one hundred thousand.

Most herbivores (plant eaters, like the elephant) possess teeth adapted for cutting and tearing off plant materials. However, except for the very young or infirm, elephants always use their trunks to tear up their food and then place it in their mouth. They will graze on grass or reach up into trees to grasp leaves, fruit, or entire branches. If the desired food item is too high up, the elephant will wrap its trunk around the tree or branch and shake its food loose or sometimes simply knock the tree down altogether. The trunk is also used for drinking. Elephants suck water up into the trunk (up to fifteen quarts or fourteen litres at a time) and then blow it into their mouth. Elephants also inhale water to spray on their body during bathing. On top of this watery coating, the animal will then spray dirt and mud, which act as a protective sunscreen. When swimming, the trunk makes an excellent snorkel.

This appendage also plays a key role in many social interactions. Familiar elephants will greet each other by entwining their trunks, much like a handshake. They also use them while play-wrestling, caressing during courtship and mother / child interactions, and for dominance displays – a raised trunk can be a warning or threat, while a lowered trunk can be a sign of submission. Elephants can defend themselves very well by flailing their trunk at unwanted intruders or by grasping and flinging them.

An elephant also relies on its trunk for its highly developed sense of smell. Raising the trunk up in the air and swivelling it from side to side, like a periscope, it can determine the location of friends, enemies, and food sources.

Tusks

The tusks of an elephant are its second upper incisors. Tusks grow continuously; an adult male's tusks will grow about 18 cm (7 in) a year. Tusks are used to dig for water, salt, and roots; to debark trees, to eat the bark; to dig into baobab trees to get at the pulp inside; and to move trees and branches when clearing a path. In addition, they are used for marking trees to establish territory and occasionally as weapons.

Like humans who are typically right- or left-handed, elephants are usually right- or left-tusked. The dominant tusk, called the master tusk, is generally shorter and more rounded at the tip from wear. Both male and female African elephants have large tusks that can reach over 3 m (10 ft) in length and weigh over 90 kg (200 lb). In the Asian species, only the males have large tusks. Female Asians have tusks which are very small or absent altogether. Asian males can have tusks as long as the much larger Africans, but they are usually much slimmer and lighter; the heaviest recorded is 39 kg (86 lb). The tusk of both species is mostly made of calcium phosphate in the form of apatite. As a piece of living tissue, it is relatively soft (compared with other minerals such as rock), and the tusk, also known as ivory, is strongly favoured by artisans for its carvability. The desire for elephant ivory has been one of the major factors in the reduction of the world's elephant population.

Some extinct relatives of elephants had tusks in their lower jaws in addition to their upper jaws, such as Gomphotherium, or only in their lower jaws, such as Deinotherium.

Teeth

Elephants' teeth are very different from those of most other mammals. Over their lives they usually have 28 teeth. These are:

  • The two upper second incisors: these are the tusks.
  • The milk precursors of the tusks.
  • 12 premolars, 3 in each side of each jaw.
  • 12 molars, 3 in each side of each jaw.

Unlike most mammals, which grow baby teeth and then replace them with a permanent set of adult teeth, elephants have cycles of tooth rotation throughout their entire life. After one year the tusks are permanent, but the molars are replaced six times in an average elephant's lifetime. The teeth do not emerge from the jaws vertically like with human teeth. Instead, they have a horizontal progression, like a conveyor belt. New teeth grow in at the back of the mouth, pushing older teeth toward the front, where they wear down with use and the remains fall out. When an elephant becomes very old, the last set of teeth is worn to stumps, and it must rely on softer foods to chew. Very elderly elephants often spend their last years exclusively in marshy areas where they can feed on soft wet grasses. Eventually, when the last teeth fall out, the elephant will be unable to eat and will die of starvation. Were it not for tooth wearout, their metabolism would allow them to live much longer. Rupert Sheldrake has proposed this as an explanation for the elephant graveyards. However, as more habitat is destroyed, the elephants' living space becomes smaller and smaller; the elderly no longer have the opportunity to roam in search of more appropriate food and will, consequently, die of starvation at an earlier age.

Tusks in the lower jaw are also second incisors. These grew out large in Deinotherium and some mastodons, but in modern elephants they disappear early without erupting.

Skin

Elephants are called pachyderms, which means thick-skinned animals. An elephant's skin is extremely tough around most parts of its body and measures about 2.5 centimetres (1 in) thick. However, the skin around the mouth and inside of the ear is paper thin. Normally, the skin of an Asian is covered with more hair than its African counterpart. This is most noticeable in the young. Asian calves are usually covered with a thick coat of brownish red fuzz. As they get older, this hair darkens and becomes more sparse, but it will always remain on their heads and tails.

The species of elephants are typically greyish in colour, but the Africans very often appear brown or reddish from wallowing in mud holes of coloured soil. Wallowing is actually a very important behaviour in elephant society. Not only is it important for socialization, but the mud acts as a sunscreen, protecting their skin from harsh ultraviolet radiation. Though tough, an elephant's skin is very sensitive. Without regular mud baths to protect it from burning, as well as from insect bites and moisture loss, an elephant's skin would suffer serious damage. After bathing, the elephant will usually use its trunk to blow dirt on its body to help dry and bake on its new protective coat. As elephants are limited to smaller and smaller areas, there is less water available, and local herds will often come too close over the right to use these limited resources.

Wallowing also aids the skin in regulating body temperatures. Elephants spend every day fighting an uphill battle to stay cool. They have a very difficult time releasing heat through the skin because, in proportion to their body size, they have very little of it. The ratio of an elephant's mass to the surface area of its skin is many times that of a human. Elephants have even been observed lifting up their legs to expose the soles of their feet, presumably in an effort to expose more skin to the air. Since wild elephants live in very hot climates, they must have other means of getting rid of excess heat.

Legs and feet

An elephant's legs are great straight pillars, as they must be to support its bulk. The elephant needs less muscular power to stand because of its straight legs and large pad like feet. For this reason an elephant can stand for very long periods of time without tiring. In fact, African elephants rarely lie down unless they are sick or wounded. Indian elephants, in contrast, lie down frequently.

The feet of an elephant are nearly round. African elephants have three nails on each hind foot, and four on each front foot. Indian elephants have four nails on each hind foot and five on each front foot. Beneath the bones of the foot is a tough, gelatinous material that acts as a cushion or shock absorber. Under the elephant's weight the foot swells, but it gets smaller when the weight is removed. An elephant can sink deep into mud, but can pull its legs out readily because its feet become smaller when they are lifted.

An elephant is a good swimmer, but it can neither trot, jump, nor gallop. It does have two gaits: a walk, and a faster gait that is similar to running. In walking the legs act as pendulums, with the hips and shoulders rising and falling while the foot is planted on the ground. With no "aerial phase," the faster gait does not meet all the criteria of running, as elephants always have at least one foot on the ground. However an elephant moving fast uses its legs like a running animal does, with the hips and shoulders falling and then rising while the feet are on the ground. In this gait an elephant will have three feet off the ground at one time. As both of the hind feet and both of the front feet are off the ground at the same time, this gait has been likened to the hind legs and the front legs taking turns running. Although they start this "run" at only 8 km/h, elephants may reach 25 km/h, all the while using the same gait. At this speed most other four-legged creatures are well into a gallop, even with leg length accounted for. Spring-like kinetics may explain the difference between the motion of these and other animals.

Ears

The large flapping ears of an elephant are also very important for temperature regulation. Elephant ears are made of a very thin layer of skin stretched over cartilage and a rich network of blood vessels. On hot days, elephants will flap their ears constantly, creating a slight breeze. This breeze cools the surface blood vessels, and then the cooler blood gets circulated to the rest of the animal's body. The hot blood entering the ears can be cooled as much as ten degrees Fahrenheit before returning to the body. Differences in the ear sizes of African and Asian elephants can be explained, in part, by their geographical distribution. Africans originated and stayed near the equator, where it is warmer. Therefore, they have bigger ears. Asians live farther north, in slightly cooler climates, and thus have smaller ears.

The ears are also used in certain displays of aggression and during the males' mating period. If an elephant wants to intimidate a predator or rival, it will spread its ears out wide to make itself look more massive and imposing. During the breeding season, males give off an odour from a gland located behind their eyes. Joyce Poole, a well-known elephant researcher, has theorized that the males will fan their ears in an effort to help propel this "elephant cologne" great distances.

Walking at a normal pace an elephant covers about 3 to 6 km/h (2 to 4 mph) but they can reach 40 km/h (24 mph) at full speed.

Evolution

Although the fossil evidence is uncertain, scientists discovered genetic evidence that the elephant family shares distant ancestry with the Sirenians (sea cows) and the hyraxes through gene comparisons. In the distant past, members of the hyrax family grew to large sizes, and it seems likely that the common ancestor of all three modern families was some kind of amphibious hyracoid.

One theory suggests that these animals spent most of their time under water, using their trunks like snorkels for breathing. Modern elephants have retained this ability and are known to swim in that manner for up to 6 hours and 50 km.

In the past, there was a much wider variety of elephant genera, including the mammoths, stegodons and deinotheria. There was also a much wider variety of species.

Diet

Elephants are herbivores, spending 16 hours a day collecting plant food. Their diet is at least 50% grasses, supplemented with leaves, bamboo, twigs, bark, roots, and small amounts of fruits, seeds and flowers. Because elephants only digest 40% of what they eat, they have to make up for their digestive system's lack of efficiency in volume. An adult elephant can consume 140–270 kg (300–600 lb) of food a day. 60% of that food leaves the elephant's body undigested.

Intelligence

With a mass just over 5 kg ((11 lb), elephant brains are larger than those of any land animal, and although the largest whales have body masses twentyfold those of a typical elephant, whale brains are barely twice the mass of an elephant's. A wide variety of behaviour, including those associated with grief, art, play, use of tools, compassion and self-awareness evidence a highly intelligent species on par with cetaceans and primates.

The largest areas in elephant brain are those responsible for hearing, smell and movement coordination, and a large portion of the brain has to do with trunk management and sensitivity.

Increased out of any comparative proportion, the temporal lobe, responsible for processing of audio information, hearing and language, is relatively far greater than that of dolphins (which use elaborate echolocation) and humans (who use language and symbols).

Senses

The sensory capabilities of elephants are specific in their extremely well innervated trunks, and their exceptional sense of hearing and smell. The hearing receptors reside not only in ears, but also in trunks that are sensitive to vibrations, and most significantly feet, which have special receptors for low frequency sound and are exceptionally well innervated. It is believed that sound communication between elephants on large distances, through the ground, is important in their social lives, and elephants are observed listening by putting trunks on the ground and carefully moving their very sensitive feet.

Social behavior

Elephants live in a very structured social order. The social lives of male and female elephants are very different. The females spend their entire lives in tightly knit family groups made up of mothers, daughters, sisters, and aunts. These groups are led by the eldest female, or matriarch. Adult males, on the other hand, live mostly solitary lives.

The social circle of the female elephant does not end with the small family unit. In addition to encountering the local males that live on the fringes of one or more groups, the female's life also involves interaction with other families, clans, and subpopulations. Most immediate family groups range from five to fifteen adults, as well as a number of immature males and females. When a group gets too big, a few of the elder daughters will break off and form their own small group. They remain very aware of which local herds are relatives and which are not.

The life of the adult male is very different. As he gets older, he begins to spend more time at the edge of the herd, gradually going off on his own for hours or days at a time. Eventually, days become weeks, and somewhere around the age of fourteen, the mature male, or bull, sets out from his natal group for good. While males do live primarily solitary lives, they will occasionally form loose associations with other males. These groups are called bachelor herds. The males spend much more time than the females fighting for dominance with each other. Only the most dominant males will be permitted to breed with cycling females. The less dominant ones must wait their turn. It is usually the older bulls, forty to fifty years old, that do most of the breeding. The dominance battles between males can look very fierce, but typically they inflict very little injury. Most of the bouts are in the form of aggressive displays and bluffs. Ordinarily, the smaller, younger, and less confident animal will back off before any real damage can be done. However, during the breeding season, the battles can get extremely aggressive, and the occasional elephant is injured. During this season, known as musth, a bull will fight with almost any other male it encounters, and it will spend most of its time hovering around the female herds, trying to find a receptive mate.

Self-awareness

Mirror self recognition is a test of self awareness and cognition used in animal studies. A mirror was provided and visible marks were made on the elephant. The elephants investigated these marks, that were visible only via the mirror. The tests also included non-visible marks to rule out the possibility of their using other senses to detect these marks. This shows that elephants recognize the fact that the image in the mirror is their own self and such abilities are considered the basis for empathy, altruism and higher social interactions. This ability had earlier only been demonstrated in humans, apes and dolphins.

Homosexuality

African as well as Asiatic males will engage in same-sex bonding and mounting. Such encounters are often associated with affectionate interactions, such as kissing, trunk intertwining, and placing trunks in each other's mouths. The encounters are analogous to heterosexual bouts, one male often extending his trunk along the other's back and pushing forward with his tusks to signify his intention to mount. Unlike heterosexual relations, which are always of a fleeting nature, those between males result in a "companionship", consisting of an older individual and one or two younger, attendant males. Same-sex relations are common and frequent in both sexes, with Asiatic elephants in captivity devoting roughly 45% of sexual encounters to same-sex activity.

Communication

Elephants communicate over long distances by producing and receiving low-frequency sound (infrasound), a sub-sonic rumbling, which can travel through the ground farther than sound travels through the air. This can be felt by the sensitive skin of an elephant's feet and trunk, which pick up the resonant vibrations much as the flat skin on the head of a drum. To listen attentively, every member of the herd will lift one foreleg from the ground, and face the source of the sound, or often lay its trunk on the ground. The lifting presumably increases the ground contact and sensitivity of the remaining legs. This ability is thought also to aid their navigation by use of external sources of infrasound. Discovery of this new aspect of elephant social communication and perception came with breakthroughs in audio technology, which can pick up frequencies outside the range of the human ear. Pioneering research in elephant infrasound communication was done by Katy Payne, of the Elephant Listening Project, and is detailed in her book Silent Thunder. Though this research is still in its infancy, it is helping to solve many mysteries, such as how elephants can find distant potential mates, and how social groups are able to coordinate their movements over extensive range.

Reproduction, calves, and calf rearing

Reproduction

Females (cows) reach sexual maturity at around 9–12 years of age and become pregnant for the first time, on average, around age 13. They can reproduce until ages 55–60. Females give birth at intervals of about 5 years. Their gestation (pregnancy) period lasts about 22 months (630–660 days), the longest gestation period of any mammal, after which typically one calf is born. Twins are rare. Labour ranges in length from 5 minutes to 60 hours. The average length of labour is 11 hours. At birth, calves weigh around 90–115 kg (200–250 lb), and they gain 1 kg (2–2.5 lb) a day. In the wild, the mother is accompanied by other adult females (aunts), who protect the young, and baby elephants are raised and nurtured by the whole family group, practically from the moment of birth.

Motherhood and calf rearing

  • The first sound a newborn calf usually makes is a sneezing or snorting sound to clear its nasal passages of fluids. (In the first few minutes after a captive birth, the keepers must monitor the calf closely for the first sound or movement. Whichever happens first, the mother typically responds to her new baby with surprise and excitement.)
  • With the help of its mother, a newborn calf usually struggles to its feet within 30 minutes of birth. For support, it will often lean against its mother's legs.
  • A newborn calf usually stands within one hour and is strong enough to follow its mother in a slowly moving herd within a few days.
  • Unlike most mammals, female elephants have a single pair of mammary glands located just behind the front legs. When born, a calf is about 90 cm (3 ft) high, just tall enough to reach its mother's nipples.
  • A calf suckles with its mouth, not its trunk, which has no muscle tone. To clear the way to its mouth so it can suckle, the calf will flop its trunk onto its forehead.
  • A newborn calf suckles for only a few minutes at a time but many times per day, consuming up to 11 litres (3 U.S. gallons) of milk in a single day.
  • A calf may nurse for up to 2 years or more. Complete weaning depends on the disposition of the mother, the amount of available milk, and the arrival of another calf.
  • Newborn calves learn mainly by observing adults, not from instinct. For example, a calf learns how to use its trunk by watching older elephants using their trunks.
  • It takes several months for a calf to control the use of its trunk. This can be observed as the calf trips over its trunk or as the trunk wiggles like a rubbery object when the calf shakes its head.

Elephant calves

Elephant social life, in many ways, revolves around breeding and raising of the calves. A female will usually be ready to breed around the age of thirteen, at which time she will seek out the most attractive male to mate with. Females are generally attracted to bigger, stronger, and, most importantly, older males. Such a reproductive strategy tends to increase their offspring's chances of survival.

After a twenty-two-month pregnancy, the mother will give birth to a calf that will weigh about 113 kg (250 lb) and stand over 76 cm (2.5 ft) tall. Elephants have a very long childhood. They are born with fewer survival instincts than many other animals. Instead, they must rely on their elders to teach them the things they need to know. The ability to pass on information and knowledge to their young has always been a major asset in the elephant's struggle to survive. Today, however, the pressures humans have put on the wild elephant populations, from poaching to habitat destruction, mean that the elderly often die at a younger age, leaving fewer teachers for the young.

All members of the tightly knit female group participate in the care and protection of the young. Since everyone in the herd

is related, there is never a shortage of baby-sitters. In fact, a new calf is usually the centre of attention for all herd members. All the adults and most of the other young will gather around the newborn, touching and caressing it with their trunks. The baby is born nearly blind and at first relies, almost completely, on its trunk to discover the world around it.

Allomothers

After the initial excitement dies down, the mother will usually select several full-time baby-sitters, or "allomothers", from her group. According to Cynthia Moss, a well known researcher, these allomothers will help in all aspects of raising the calf. They walk with the young as the herd travels, helping the calves along if they fall or get stuck in the mud. The more allomothers a baby has, the more free time its mother has to feed herself. Providing a calf with nutritious milk means the mother has to eat more nutritious food herself. So, the more allomothers, the better the calf's chances of survival. An elephant is considered an allomother when she is not able to have her own baby. A benefit of being an allomother is that she can gain experience or receive assistance when caring for her own calf.

Effect on the environment

Elephants' foraging activities affect the areas in which they live:

  • By pulling down trees to eat leaves, breaking branches, and pulling out roots they create clearings in which new young trees and other vegetation grow to provide future nutrition for elephants and other organisms.
  • Elephants make pathways through the environment that are used by other animals to access areas normally out of reach. The pathways have been used by several generations of elephants, and today people are converting many of them to paved roads.
  • During the dry season elephants use their tusks to dig into dry river beds to reach underground sources of water. These newly dug water holes may become the only source of water in the area.
  • Elephants are a species w hich many other organisms depend on. For example, termites eat elephant feces and often begin building termite mounds under piles of elephant feces.

Threat of extinction

Hunting

The threat to the African elephant presented by the ivory trade is unique to the species. Larger, long-lived, slow-breeding animals, like the elephant, are more susceptible to overhunting than other animals. They cannot hide, and it takes many years for an elephant to grow and reproduce. An elephant needs an average of 140 kg (300 lb) of vegetation a day to survive. As large predators are hunted, the local small grazer populations (the elephant's food competitors) find themselves on the rise. The increased number of herbivores ravage the local trees, shrubs, and grasses. Elephants themselves have few natural predators besides man and, occasionally, lions.

Dehabitation

Another threat to elephant's survival in general is the ongoing cultivation of their habitats with increasing risk of conflicts of interest with human cohabitants. These conflicts kill 150 elephants and up to 100 people per year in Sri Lanka. Lacking the massive tusks of its African cousins, the Asian elephant's demise can be attributed mostly to loss of its habitat.

As larger patches of forest disappear, the ecosystem is affected in profound ways. The trees are responsible for anchoring soil and absorbing water runoff. Floods and massive erosion are common results of deforestation. Elephants need massive tracts of land because, much like the slash-and-burn farmers, they are used to crashing through the forest, tearing down trees and shrubs for food and then cycling back later on, when the area has regrown. As forests are reduced to small pockets, elephants become part of the problem, quickly destroying all the vegetation in an area, eliminating all their resources.

National parks

Africa's first official reserve eventually became one of the world's most famous and successful national parks. Kruger National Park in South Africa first became a reserve against great opposition in 1898 (then Sabi Reserve). It was deproclaimed and reproclaimed several times before it was renamed and granted national park status in 1926. It was to be the first of many.

Of course, there were many problems in establishing these reserves. For example, elephants range through a wide tract of land with little regard for national borders. however, when most parks were created, the boundaries were drawn at the human-made borders of individual countries. Once a fence was erected, many animals found themselves cut off from their winter feeding grounds or spring breeding areas. Some animals died as a result, while some, like the elephants, just trampled through the fences. This did little to belie their image as a crop-raiding pest. The more often an elephant wandered off its reserve, the more trouble it got into, and the more chance it had of being shot by an angry farmer. When confined to small territories, elephants can inflict an enormous amount of damage to the local landscapes. Today there are still many problems associated with these parks and reserves, but there is now little question as to whether or not they are necessary. As scientists learn more about nature and the environment, it becomes very clear that these parks may be the elephant's last hope against the rapidly changing world around them.

Additionally, Kruger National Park has suffered from elephant overcrowding, at the expense of other species of wildlife within the reserve. South Africa slaughtered 14,562 elephants in the reserve between 1967 and 1994; it stopped in 1995, mostly due to international and local pressure. Without action, it is predicted that the elephant population in Kruger National Park will triple to 34,000 by 2020.

Humanity and elephants

Harvest from the wild

The harvest of elephants, both legal and illegal, has had some unexpected consequences on elephant anatomy as well. African ivory hunters, by killing only tusked elephants, have given a much larger chance of mating to elephants with small tusks or no tusks at all. The propagation of the absent-tusk gene has resulted in the birth of large numbers of tuskless elephants, now approaching 30% in some populations (compare with a rate of about 1% in 1930). Tusklessness, once a very rare genetic abnormality, has become a widespread hereditary trait.

It is possible, if unlikely, that continued selection pressure could bring about a complete absence of tusks in African elephants, a development normally requiring thousands of years of evolution. The effect of tuskless elephants on the environment, and on the elephants themselves, could be dramatic. Elephants use their tusks to root around in the ground for necessary minerals, tear apart vegetation, and spar with one another for mating rights. Without tusks, elephant behaviour could change dramatically.

Domestication and use

Elephants have been working animals used in various capacities by humans. Seals found in the Indus Valley suggest that the elephant was first domesticated in ancient India. However, elephants have never been truly domesticated: the male elephant in his periodic condition of musth is dangerous and difficult to control. Therefore elephants used by humans have typically been female, war elephants being an exception, however: as female elephants in battle will run from a male, only males could be used in war. It is generally more economical to capture wild young elephants and tame them than breeding them in captivity.

War elephants were used by armies in the Indian sub-continent, and later by the Persian empire. This use was adopted by Hellenistic armies after Alexander the Great experienced their worth against king Porus, notably in the Ptolemaic and Seleucid diadoch empires. The Carthaginian general Hannibal took elephants across the Alps when he was fighting the Romans, but brought too few elephants to be of much military use, although his horse cavalry was quite successful; he probably used a now-extinct third African (sub)species, the North African (Forest) elephant, smaller than its two southern cousins, and presumably easier to domesticate. A large elephant in full charge could cause tremendous damage to infantry, and cavalry horses would be afraid of them Throughout Siam, India, and most of South Asia elephants were used in the military for heavy labour, especially for uprooting trees and moving logs, and were also commonly used as executioners to crush the condemned underfoot.

Elephants have also been used as mounts for safari-type hunting, especially Indian shikar (mainly on tigers), and as ceremonial mounts for royal and religious occasions, whilst Asian elephants have been used for transport and entertainment, and are common to circuses around the world.

African elephants have long been reputed to not be domesticable, but some entrepreneurs have succeeded by bringing Asian mahouts from Sri Lanka to Africa. In Botswana, Uttum Corea has been working with African elephants and has several young tame elephants near Gaborone. African elephants are more temperamental than Asian elephants, but are easier to train. Because of their more sensitive temperaments, they require different training methods than Asian elephants and must be trained from infancy hence Corea worked with orphaned elephants. African elephants are now being used for (photo) safaris. Corea's elephants are also used to entertain tourists and haul logs.

Elephants are also commonly exhibited in zoos and wild animal parks, the former of which has caused controversy. Animal rights advocates allege that elephants in zoos "suffer a life of chronic physical ailments, social deprivation, emotional starvation, and premature death". However, zoos argue that standards for treatment of elephants are extremely high and that minimum requirements for such things as minimum space requirements, enclosure design, nutrition, reproduction, enrichment and veterinary care are set to ensure the wellbeing of elephants in captivity.

Tuesday, October 9, 2007

Creature Who Inspired The Legend

The Beluga Whale or White Whale (Delphinapterus leucas) is an Arctic and sub-arctic species of cetacean. This marine mammal is commonly referred to simply as the Beluga.

Taxonomy and evolution

The Beluga was first described by Peter Simon Pallas in 1776. It is a member of the Monodontidae taxonomic family alongside the Wallace family.The Irrawaddy dolphin was also once considered to be in the same family though recent genetic evidence suggests otherwise.

The earliest known ancestor of the beluga is the now-extinct Denebola brachycephala from the late Miocene period. One single fossil has been found on the Baja California peninsula, indicating that the family once thrived in warmer waters. The fossil record also indicates that in comparatively recent times the beluga's range has varied with that of the ice pack – expanded during ice ages and contracting when the ice retreats.

Naming

The Red List of Threatened Species gives both Beluga and White Whale as common names, though the former is now more popular. The English name comes from the Russian белуга (beluga) or белуха (belukha) which derives from the word белый (belyy), meaning "white". It is sometimes referred to by scientists as the Belukha Whale in order to avoid confusion with the Beluga sturgeon. The whale is also colloquially known as the "Sea Canary" on account of the high-pitched squeaks, squeals and whistles.

Description

This small whale can be up to 5 metres (16 ft) long, larger than all but the largest dolphins but smaller than most other toothed whales. Males are generally larger than the female - males can weigh 1,360 kg (3,000 lb) and females about 900kg (one short ton).

Newly-born belugas are about 1.5 m (5 ft) long and weigh 80 kilograms (176 lb). This whale is unmistakable when adult: it is all white and has a dorsal ridge rather than a fin. The head is also unlike that of any other cetacean - its melon is extremely bulbous and even malleable. The beluga is able to change the shape of its head by blowing air around its sinuses. Again unlike many dolphins and whales, the vertebrae in the neck are not fused together, allowing the animal flexibility to turn its head laterally.

The absence of the dorsal fin is reflected in the genus name of the species - apterus is the Greek for "wingless". The evolutionary preference for a dorsal ridge in favour of a fin is believed by scientists to be adaptation to under-ice conditions, or possibly as a way of preserving heat. Like in other cetaceans the thyroid gland is relatively large compared to terrestrial mammals (three times per weight as a horse) and may help to sustain higher metabolism during the summer estuarine occupations.

The body of the Beluga is rotund, particularly when well-fed, and tapers smoothly to both the head and tail. The tail fin grows and becomes increasingly ornately curved as the animal ages. The flippers are broad and short - making them almost square-shaped.

Males become sexually mature at eight years, females at five. Seasonally polyestrus females give birth to a single calf in the spring after a gestation period of fifteen months with ranges found from 14.5 in the wild to 15-17 months in captivity. Young Belugas are uniformly dark grey in colour. The grey steadily lightens as they grow up - reaching their distinctive pure white colour by the age of seven in females and nine in males. The nursing period is about two years in length. The mating process is not properly understood. Testosterone levels in males have been found to be lowest in September and then rose to be highest in march with peak sperm production thought to occur perhaps in May or June if their physiology mimics other mammals. Mating certainly does occur during the winter or early spring, when the animals are still in their winter grounds or have begun their migration. However, mating occurs at other times, leaving open the possibility of delayed implantation. Belugas can live for up to fifty years. Females in captivity have been found to conceive as old as 20 years.

Distribution

White Whale (Beluga Whale, Delphinapterus leucas) at the mouth of Churchill River into Hudson Bay, Canada

The beluga moves in Arctic and sub-Arctic waters ranging from 50° N to 80° N. There is also an isolated population which travels in the St. Lawrence River estuary and the Saguenay fjord, around the village of Tadoussac, Quebec. There is also a threatened population that lives in the Cook Inlet, Alaska. In the spring beluga move to their summer grounds, bays, estuaries and other shallow inlets. These summer sites are detached from one another and a mother will usually return to the same site year after year. As their summer homes become clogged with ice during autumn, beluga move away for winter. Most travel in the direction of the advancing ice-pack and stay close to the edge of it for the winter months. Others stay under the iced area - surviving by finding ice leads and polynyas (patches of open water in the ice) in which they can surface to breathe. Beluga may also find pockets of air trapped under the ice. The remarkable ability of the beluga to find the thin slivers of open water where the dense ice pack may cover more than 95% of the sea surface is still a source of mystery and great interest to scientists. It is clear that the echo-location capabilities of the Beluga are highly adapted to the peculiar acoustics of the sub-ice sea and it has been suggested that Beluga can sense open water through echo-location.

On June 9, 2006, the carcass of a young beluga whale was found in the Tanana River near Fairbanks in central Alaska, nearly 1,600 kilometres (1,000 miles) from its nearest natural ocean habitat. As beluga sometimes follow migrating fish, Tom Seaton, an Alaska state biologist, speculated that it had followed migrating salmon up the river at some point in the prior fall.

Behavior

Beluga whales are highly sociable creatures. They move in pods which commonly contain animals of the same gender and age. Groups of males may number in the hundreds, but mothers with calves generally mix in slightly smaller groups. When pods aggregate in estuaries, they may number in the thousands. This can represent a significant proportion of the entire Beluga population and is the time when they are most vulnerable to hunting.

Beluga pods tend to be unstable, meaning that belugas tend to move from pod to pod. Pod membership is rarely permanent. Radio-tracking has shown belugas can start out in a pod and within a few days be hundreds of miles away from that pod. The closest social relationship between belugas is the mother-calf relationship. Nursing times of 2 years have been observed and lactational anestrus may not occur. Calves often return to the same estuary as their mother in the summer, meeting with their mother sometimes even afterbecoming fully mature.

Beluga are also known for being rather playful, as well as spitting at humans or other whales. It is not unusual for an aquarium handler to be sprayed down by one of his charges whilst tending a beluga tank. Some researchers believe that this skill may be utilized to blow away sand from crustaceans at the sea bottom.

Diet

Belugas are slow-swimming mammals which feed mainly on fish. They also eat cephalopods (squid and octopus) and crustaceans (crab and shrimp). Foraging on the seabed typically takes place at depths of up to 1,000 feet, but they can dive at least twice this depth. Generally a feeding dive will last 3-5 minutes, but belugas have been observed submerged for up to 20 minutes at a time.

Vocalizations

Beluga are amongst the loudest animals in the sea. They exhibit a wide range of vocalizations including clicks, squeaks, whistles, squarks and a bell-like clang. One noted researcher in the field likens a noisy beluga pod to the string section of an orchestra tuning up before a concert. Researchers have recorded 50 distinct sounds; most in the range of 0.1 to 12 kHz.

Population, threats, and human interactions

The global population of beluga today stands at about 100,000. Although this number is much greater than that of other cetaceans, it is much smaller than historical populations before decades of over-hunting. There are estimated to be 40,000 individuals in the Beaufort Sea, 25,045 in Hudson Bay, 18,500 in the Bering Sea and 28,008 in the Canadian Low Arctic. The population in the St. Lawrence estuary is estimated to be around 1000. They are considered an excellent sentinel species and indicator of the health of, and changes in, the environment. This is as they are long lived, on top of the food web, with large amounts of fat and blubber, relatively well studied for a cetacean, and still somewhat common.

The beluga's natural predators are polar bears, who hunt when the whales become encircled by ice during winter. In these cases many miles of ice separate groups of Belugas from the open ocean, and as a result they are unable to leave until the ice melts in spring. During this period belugas do not offer much resistance to bear attacks due to their low energy reserves.

Because beluga congregate in river estuaries, human-caused pollution isproving to be a significant danger to their health. Incidents of cancer have been reported to be rising as a result of the St. Lawrence River pollution. The bodies of the Beluga residents in this area contain so many contaminants that their carcasses are treated as toxic waste. Reproductive pathology has been discovered in the population here and many suspect organochlorines to be responsible. Levels between 240 ppm and 800 ppm of PCBs have been found, with males typically having higher levels. It is not known what the long-term effects of this pollution will be on the affected populations.

Erysipelothrix rhusiopathiae gram positive/variable bacilli, likely from contaminated fish in the diet, can endanger the beluga causing anorexia, dermal plaques, and lesions. This may lead to death if not diagnosed early and treated with antibiotics. Cetaceans seem quite vulnerable to pneumonia, and various species of the aerobic actinomycete Nocardia, likely more problematic when anything causes more soil or dust to become airborne, (spreading the organisms to the water or air the belugas breath), can be worrisome and can lead to death.

Belugas were amongst the first whale species to be brought into captivity. The first beluga was shown at Barnum's Museum in New York in 1861. Today it remains one of the few whale species kept at aquaria and sea life parks across North America, Europe and Asia. Their popularity there with visitors reflects their attractive color, and their range of facial expressions. While most cetacean "smiles" are fixed, the extra movement afforded by the beluga's unfused cervical vertebrae allows a greater range of expression. Most beluga found in aquariums are caught in the wild, though captive breeding programs have enjoyed some success.

Indirect human disturbance may also be a threat to the species. While some populations have come to tolerate small boats, others have been known to actively try to avoid ships. Whale-watching beluga has become a huge and booming activity in the St. Lawrence and Churchill River areas.

Because of their predictable migration pattern and high concentrations, beluga have been hunted by indigenous Arctic peoples for centuries. In many areas a pattern of hunting, believed to be sustainable, continues to this day. However, in other areas, such as the Cook Inlet, Ungava Bay, and off west Greenland, previous commercial catches (now banned under the general moratorium on whaling) left the populations in great peril. Indigenous whaling continues in these areas, and some populations continue to decline. These areas are the subject of intensive dialogue between Inuit communities and national governments aiming to create a sustainable hunt and are the reason that the beluga has been listed as vulnerable on the IUCN Red List of Threatened Species since 1995.

Both the United States Navy and the Soviet Navy have used belugas in anti-mining operations in Arctic waters.