Animals A to Z - Recently Updated Pages

Albatross

Tagasaki — Tue, 24 Jul 2007 00:34:02 CDT

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Africanized Bee

Tagasaki — Sat, 25 Nov 2006 23:13:24 CST

Africanized honey bees (AHB), (known colloquially as "killer bees") are hybrids of the African honey bee, Apis mellifera scutellata (not A.m. adansoniir; see Collet et al., 2006), with various European honey bees such as the Italian bee A.m. ligustica and A.m. iberiensis.
The Africanized bees in the western hemisphere descended from 26 Tanzanian queen bees (A. m. scutellata) accidentally released in 1957 in Piracicaba-Sao Paulo State in the south of Brazil from hives operated by biologist Warwick E. Kerr, who had interbred European honey bees and bees from southern Africa. Hives containing these particular queens were noted to be especially defensive. Kerr was attempting to breed a strain of bees that would be better adapted to tropical conditions (i.e., more productive) than the European bee used in North America and southern South America. The African queens eventually mated with local drones, and their descendants have since spread throughout the American continent. While the African source bees are significantly smaller than the European bees, the hybrids are similar to the European bees in size, with a slightly shorter wing their only visible difference. Due to individual variations, a large sample must be examined in order to distinguish the two breeds. The Africanized hybrid bees have become the preferred type of bee for beekeeping in Central America and in tropical areas of South America because of improved productivity. However, in most areas the Africanized hybrid is initially feared because it tends to retain certain behavioral traits from its African ancestors that make it less desirable for domestic beekeeping. Specifically (as compared with the European bee types), the Africanized bee:

Tends to swarm more frequently.
Is more likely to migrate as part of a seasonal response to lowered food supply.
Has greater defensiveness when in a resting swarm.
Lives more often in ground cavities than the European types.
Guards the hive aggressively, with a larger alarm zone around the hive.
Has a higher proportion of "guard" bees within the hive.
Deploys in greater numbers for defense, and pursues perceived threats over much longer distances from the hive.
Cannot survive extended periods of forage deprivation, preventing intrusion into areas with harsh Winters or extremely dry late Summers.

African Wild Dogs

Tagasaki — Sat, 25 Nov 2006 23:01:46 CST

The African Wild Dog, Lycaon pictus also known as the African Hunting Dog, Cape Hunting Dog or Painted Hunting Dog, is a mammal of the Canidae family, and thus related to the domestic dog. It is the only species in monotypic genus, Lycaon, and the only species in the canid family to lack dewclaws on the forelimbs. They are, as their name indicates, found only in Africa, especially in scrub savanna and other lightly wooded areas. The Latin name of the species means painted wolf and it is characteristic of the species that no two individuals have the same pattern of coat. The pelage is an irregular pattern of black, yellow, and white. Some areas of the body are nearly hairless, and the skin is black.
African Wild Dogs hunt in packs. Their main prey are impala and similar medium sized ungulates. They're known for their stamina and for being clever hunters; they have been observed hunting prey in relays, or even blocking a potential escape route for prey. As a result, African Wild Dogs enjoy the highest kill per hunt rate of predators on the savannah (up to 98%). Members of a hunting pack vocalize to help coordinate their movements. Their voice is characterized by an unusual chirping or squeaking sound, similar to a bird. After a hunt, dogs will often regurgitate meat for members of the group that have stayed behind, including the old, the lame, the pups, and subordinate adults who have taken on the responsibility of caring for the pups. Their need for a large territory has led to the situation where today they are threatened with extinction. Their relatively small physique also makes them vulnerable to attacks by their competitors, lions and hyenas. The dogs are also killed by livestock herders and game hunters. They tend to be elusive and unlike most other members of the dog family, are extremely difficult to tame.
They have a highly complex social system, within which related adult members cooperate to produce a single litter of pups annually. The breeding female occupies a den while she bears the pups, usually selecting an abandoned aardvark burrow for this purpose. Most populations have more males than females because more male pups appear in litters. It is very unusual among mammals to have this kind of gender bias. Females are more likely to disperse from the natal group, and they readily join packs which have no sexually mature female members. In packs with more than one female, only one will be allowed to breed, leading to vicious rivalry between females.
The current estimate for remaining wild dogs in the wild is approximately 5,600. Of these, the majority live in the two remaining large populations associated with the Selous Game Reserve in Tanzania and the population centered in northern Botswana and eastern Namibia. Isolated populations persist in Zambia, Kenya, Mozambique, Zimbabwe and South Africa.

African Grey Parrots

Tagasaki — Sat, 25 Nov 2006 22:52:47 CST

The African Grey Parrot is a medium-sized parrot of the genus Psittacus, native to Africa. As the name implies, they are predominantly grey, with accents of white. Some of their feathers are very dark grey and others are a lighter grey colour. They have red or maroon tails depending on the subspecies. They feed primarily on nuts and fruits, supplemented by leafy matter.

Subspecies

There are two subspecies:

Congo African Grey parrot, Psittacus erithacus erithacus - these are larger birds (about 12 inches/30cm long) with light grey feathers, deep red tails and black beaks.
Timneh African Grey parrot, Psittacus erithacus timneh - these are smaller in size, have a darker charcoal gray coloring, a darker maroon tail, and a light, horn colored upper mandible.

Some avian enthusiasts (incorrectly) recognize a third subspecies, Ghana African Grey (Psittacus erithacus princeps). This bird is described to be similar to the Congo African greys, but darker and slightly smaller; however, scientifically this subspecies has not been found to be recognizable. Among breeders, there is said to be a fourth subspecies, the Cameroon African Grey, most often referred to as the big silvers.

Mimicry And Intelligence

While comparative judgements of animal intelligence are always very difficult to make objectively, Psittaciforms are generally regarded as being the most intelligent of birds. African grey parrots are particularly noted for their cognitive abilities, which are believed to have evolved as a consequence of their history of cooperative feeding on the ground in central Africa.
Irene Pepperberg's extensive research with captive African greys, especially the individual known as Alex, has shown that these parrots are capable of associating human words with their meanings, at least to some extent. Ambitious claims of language use have also been made for another African grey, N'kisi, who has a vocabulary of over one thousand words and speaks in sentences. Although there exists a great deal of debate as to just how well these birds actually understand the meaning of the words they speak, there is little doubt that Greys and other parrots (especially macaws and cockatoos), along with corvines (crows, ravens, and jays), are highly intelligent in comparison with other birds.

African Grey Parrots As Pets

The history of African Grey parrots kept as pets dates back over 4,000 years. Some Egyptian heiroglyphics clearly depict pet parrots. The ancient Greeks also valued parrots as pets, and this custom was later adopted by the Wealthy Roman families often kept parrots in ornate cages, and parrots were prized for their ability to talk. King Henry VIII of England also had an African Grey parrot. The Portuguese sailors kept them as companions on their long sea voyages.
Today, many African Grey parrots are hand reared by breeders for the pet trade and they make wonderful and very affectionate companian parrots; however, because they can be unpredictable at times, they may not be compatible with small children. African Grey parrots are very strong and they can bite with their strong beak and scratch with their talons. Pet owners often liken the experience of keeping an African Grey to raising a young child, both for the birds' intelligence and for the substantial time commitment which they require. While captive-born birds usually assimilate into their new households with relative ease, wild-caught African Grey parrots require considerably more time to adapt to living with humans, and have a tendency to growl and bite when they are approached. The Convention on the International Trade in Endangered Species (CITES) has rendered all sales of captive wild parrots illegal.
African Grey parrots, like any pet parrot, are very high-maintenance pets, as they require a great deal of personal attention. While numbers vary with each source, most agree that three hours out of cage daily and 45 minutes of physical interaction is the minimum attention required for good mental health. African Greys – particularly Congo African Greys – are known to be shy around strangers, and tend to bond solely with their main caretaker if they do not interact with different people regularly. While inter-species friendships with other parrots are uncommon with African Greys, they require socialization with other parrots of any species.
African Greys require plenty of stimulating toys to keep them from becoming bored while confined to their cage. These toys should be rotated and switched out regularly so as to maintain the bird's interest; because of their high intelligence, they quickly become tired of . For an African Grey spending most of its day in the cage, 36"W x 24"D is a good cage size. The height of a cage is typically not important, except in the case of playtop cages that are taller than the owner, in which case the bird can become territorial. An African Grey who spends most of its time on a playstand and uses the cage solely for sleeping only needs a cage large enough so that the bird's wingspan doesn't touch the cage's sides and its head and tail do not touch the cage's top and bottom, respectively. The bar-spacing should from be ¾ inch to 1 inch. A companion African Grey should be kept in a bird-safe environment and placed in a busy part of the home, such as the living room, where the bird can occupy him- or herself in watching the household activities.
African Greys have special dietary requirements and should be fed plenty of calcium- and Vitamin A-rich foods, such as almonds, small amounts of cheese, or leafy greens like mustard greens, broccoli, etc. It is usual to give African grey parrots carefully calculated quantities of calcium and vitamin supplements. An excess of these added vitamins and minerals in an African Grey’s diet can lead to health problems. Only a few feathers should be clipped from the wings of an African Grey since they are heavy birds. Clipping too many feathers can severely impair flight and may lead to injuries as they may have a tendency to crash to the ground. If very young birds are wing clipped they may never gain full coordination and agility in flight. African Grey parrots' lifespans are up to about 50 years (or more) in captivity.

African Elephants

Tagasaki — Sat, 25 Nov 2006 10:46:40 CST

African elephants are the two species of elephants in the Loxodonta genus, one of the two existing genera in Elephantidae. Although it is commonly believed that the genus was named by Georgis Cuvier in 1825, Cuvier spelled it Loxodonte. An anonymous author romanized the spelling to Loxodonta and the ICZN recognizes this as the proper authority.
Fossils from Loxodonta have only been found in Africa, where they developed in the middle Pliocene.

Species

Loxodonta adaurora, extinct, developed into the modern African elephant.

African Bush Elephant (Loxodonta africana).

African Forest Elephant (Loxodonta cyclotis).

Conservations

Poaching significantly reduced the population of Loxodonta in certain regions during the 20th century. An example of this poaching pressure is in the eastern region of Chad. Elephant herds were substantial in number as recently as 1970 with an estimated population of 300,000; however, by 2006 the number has dwindled to about 10,000. The African elephant nominally has governmental protection, but poaching is still a serious issue.

African Clawed Frog

Tagasaki — Sat, 25 Nov 2006 10:37:39 CST

The African clawed frog (Xenopus laevis, also known as platanna) is a species of South African aquatic frog of the genus Xenopus. It is up to 12 cm long with a flattened head and body but no tongue. Its name derives from its three short claws on each of its hind feet, which it probably uses to stir up mud to hide it from predators.
Although X. laevis is not blessed with the short generation time and genetic simplicity generally desired in genetic model organisms, it is an important model organism, in developmental biology. X. laevis takes 1 to 2 years to reach sexual maturity and, like most of its genus, it is teraploid. However, it does have a large and easily manipulable embryo. The ease of manipulation in amphibian embryos has given them an important place in both historical and modern developmental biology. A related species, Xenopus tropicalus, is now being promoted as a more viable model for genetics. Roger Wolcott Sperry used X. laevis for his famous experiments describing the development of the visual system. These experiments led to the formulation of the Chemoafinity hypothesis.
Xenopus oocytes provide an important expression system for molecular biology. By injecting cDNA or cRNA into the developing oocyte, scientists can study the protein products in a controlled system. This allows rapid functional expression of manipulated cDNAs (or cRNA). This is particularly useful in electrophysiology, where the ease of recording from the oocyte makes expression of membrane channels attractive. One challenge of oocyte work is eliminating native proteins that might confound results, such as membrane channels native to the oocyte. Translation of proteins can be blocked or splicing of pre-mRNA can be modified by injection of Morpholino antisense oligos into the oocyte (for distribution throughout the embryo) or early embryo (for distribution only into daughter cells of the injected cell).
X. laevis is also notable as having been a standard method of pregnancy testing. Human chorionic gonadotropin is a hormone found in substantial quantities in the urine of pregnant women; when injected into the female X. laevis it induces them to lay eggs.

African Clawed Frogs As Pets

In recent years African Clawed Frogs have become popular pets. It has been found that there is a strong connection between the international trade of X. laevis and a global decline in frog populations due to the spread of chytridiomycosis .
Often confused with the much smaller African dwarf frog, the clawed frog has webbing on its back feet but has four unwebbed fingers on each front foot. Females grow to an average of 5 inches (130 mm) snout to vent; males are generally smaller, around 3.5 to 4 inches (90 to 100 mm). They are social frogs and should be kept with others of their species. Highly carnivorous, they will attack and eat any fish kept with them. African Clawed Frogs should be kept in 10 US gallons of water per frog, and are completely aquatic. A well fitting lid is required for keeping clawed frogs, as they can leap out of most tank set-ups. As with fish-keeping, it is necessary to closely monitor water quality and change water weekly in order to keep these frogs healthy. If properly cared for, African Clawed Frogs can live over 15 years. As with African Dwarf Frogs, Clawed Frogs are sensitive to the presence of chlorine and chloramines in the water, and it is essential that a reliable method of dechlorination is used before water is added to a Clawed Frog tank.
A common mis-labeling in pet shops is the "African Dwarf Clawed Frog". Dwarf Frogs and Clawed Frogs are two independent species.

Aardvark

Tagasaki — Sat, 25 Nov 2006 07:51:46 CST

The Aardvark (Orycteropus afer) is a medium-sized mammal native to Africa. The name comes from the Afrikaans/Dutch for "earth pig" (aarde earth, varken pig), because early settlers from Europe thought it resembled a pig. However, the Aardvark is not closely related to pigs.

Classification

The Aardvark is the only surviving member of the family Orycteropodidae and of the order Tubulidentata. The Aardvark was originally placed in the same order as the South American anteaters because of superficial similarities which, it is now known, are the result of convergent evolution, not common ancestry. For the same reason, Aardvarks bear a striking first-glance resemblance to the marsupial bandicoots, bilbeis, and numbats of Australasia, which are not placental mammals at all. The Aardvark is now in its own genus, Orycteropus.
The oldest known Tubulidentata fossils have been found in Kenya and date to the early Miocene. Although the relationships of Tubulidentata are unknown, they are probably ungulates. They spread to Europe and southern Asia during the later Miocene and early Pliocene periods. Two other genera of the family Orycteropodidae are known besides the extant one: Leptorycteropus and Myorycteropus. A genus from Madagascar called Plesiorycteropus may be related to the Aardvark.
In the past, several individual species of Aardvark were named; however, current knowledge indicates that there is only one species, Orycteropus afer, with several subspecies; 18 have been identified but most are regarded as invalid.

Description

The most distinctive charactristic of the Tubulidentata is (as the name implies) their teeth, which, instead of having a pulp cavity, have a number of thin tubes of dentine, each containing pulp and held together by cementum. The teeth have no enamel coating and are worn away and regrow continuously. The Aardvark is born with conventional incisors and canines at the front of the jaw, but these fall out and are not replaced. Adult Aardvarks have only molars at the back of the jaw.
The Aardvark is only vaguely pig-like; the body is stout with an arched back; the limbs are of moderate length. The front feet have lost the pollex (or 'thumb')—resulting in four toes—but the rear feet have all five toes. Each toe bears a large, robust nail which is somewhat flattened and shovel-like, and appears to be intermediate between a claw and a hoof. The ears are disproportionately long, and the tail is very thick at the base and gradually tapers. The greatly elongated head is set on a short, thick neck, and the end of the snout bears a disc, which house the nostrils. The mouth is small and tubular, typical of species that feed on termites. The Aardvark has a long, thin, protrusible tongue and elaborate structures supporting a keen sense of smell.
Weight is typically between 40 and 65 kg; length is usually between 1 and 1.3 m. The Aardvark is a pale yellowish gray in color, often stained reddish-brown by soil. The coat is thin and the animal's primary protection is its tough skin; the Aardvark has been known to sleep in a recently excavated ant nest, so well does it protect them.

Behaviour

The Aardvark is nocturnal and is a solitary creature that feeds almost exclusively on ants and termites (formicivore); the only fruit eaten by aardvarks is the aardvark cucumber. An Aardvark emerges from its burrow in the late afternoon or shortly after sunset, and forages over a considerable home range, swinging its long nose from side to side to pick up the scent of food. When a concentration of ants or termites is detected, the Aardvark digs into it with its powerful front legs, keeping its long ears upright to listen for predators, and takes up an astonishing number of insects with its long, sticky tongue—as many as 50,000 in one night have been recorded. It is an exceptionally fast digger, but otherwise moves fairly slowly.
Aside from digging out ants and termites, the Aardvark also excavates burrows in which to live: temporary sites are scattered around the home range as refuges, and a main burrow is used for breeding. Main burrows can be deep and extensive, have several entrances and can be as long as 13 meters. The Aardvark changes the layout of its home burrow regularly, and from time to time moves on and makes a new one. Only mothers and young share burrows.
After a gestation period of 7 months, a single cub weighing around 2 kg is born, and is able to leave the burrow to accompany its mother after only two weeks. At six months of age it is able to dig its own burrows, but it will often remain with the mother until the next mating season.
Aardvarks can live to be more than 20 years in captivity.
The aardvark's main predators are lions, leopards, hunting dogs and pythons. Aardvarks can dig fast or run in zigzag fashion to elude enemies, but if all else fails, they will strike with their claws, tail and shoulders, sometimes flipping onto their backs to lash with all fours. Its thick skin also protects it to some extent.

Habitat

The Aardvark is distributed across most of Sub-Saharan Africa, and although hunted by humans both for its flesh and for its teeth (which are used as decorations), does not appear to be threatened. The Aardvark has become a staple in the diets of some tribes native to eastern Africa.

A

Tagasaki — Sat, 25 Nov 2006 07:34:49 CST