Description
The Emu Dromaius novaehollandiae, is the largest bird native to Australia and the only extant member of the genus Dromaius. It is also the second-largest extant bird in the world by height, after its ratite relative, the ostrich. The soft-feathered, brown, flightless birds reach up to 2 m (6.5 ft) in height. The Emu is common over most of mainland Australia, although it avoids heavily populated areas, dense forest and arid areas. Emus can travel great distances at a fast, economical trot and, if necessary, can sprint at 50 km/h (30 mph) for some distance at a time. They are opportunistically nomadic and may travel long distances to find food; they feed on a variety of plants and insects.
Emus are large birds. The largest can reach up to two metres (6 ft 7 inches) in height (1–1.3 metres (3.2–4.3 ft) at the shoulder) and weigh between 30 and 55 kilograms (66–121 pounds). They have small vestigial wings and a long neck and legs. Their ability to run at high speeds is due to their highly specialised pelvic limb musculature. Their feet have only three toes and a similarly reduced number of bones and associated foot muscles; they are the only birds with gastrocnemius muscles in the back of the lower legs. The pelvic limb muscles of Emus have a similar contribution to total body mass as the flight muscles of flying birds. Emus have brown to grey-brown plumage of shaggy appearance; the shafts and the tips of the feathers are black. Solar radiation is absorbed by the tips, and the loose-packed inner plumage insulates the skin. The resultant heat is prevented from flowing to the skin by the insulation provided by the coat, allowing the bird to be active during the heat of the day. A unique feature of the Emu feather is its double rachis emerging from a single shaft. Their calls consist of loud booming, drumming and grunting sounds that can be heard up to two kilometers away. The booming sound is created in an inflatable neck sac.
The giraffe (Giraffa camelopardalis) is an African even-toed ungulate mammal, the tallest of all land-living animal species, and the largest ruminant. Males can be 4.8 to 5.5 metres (16 to 18 feet) tall and weigh up to 1,700 kilograms (3,800 pounds). The record-sized bull, shot in Kenya in 1934, was 5.87 m (19.2 ft) tall and weighed approximately 2,000 kg (4,400 lb). Females are generally slightly shorter, and weigh less than the males do.
The giraffe is related to deer and cattle, but is placed in a separate family, the Giraffidae, consisting only of the giraffe and its closest relative, the okapi. Its range extends from Chad to South Africa.
Giraffes can inhabit savannas, grasslands, or open woodlands. They prefer areas enriched with acacia growth. They drink large quantities of water and, as a result, they can spend long periods of time in dry, arid areas. When searching for more food they will venture into areas with denser foliage.
The leopard (Panthera pardus) is an Old World mammal of the Felidae family and the smallest of the four big cats of the genus Panthera, which also consists of the tiger, lion and jaguar. Leopards that are melanistic, either completely black or very dark in coloration, are one of the big cats known colloquially as black panthers. The leopard is an agile and graceful predator. Although smaller than the other members of Panthera, the leopard is still able to take large prey given a massive skull that well utilizes powerful jaw muscles. Its body is comparatively long for a cat and its legs are short. Head and body length is between 90 and 190 cm (35 and 75 in), the tail reaches 60 to 110 cm (24 to 43 in). Shoulder height is 45 to 80 cm (18-31 in). Males are considerably larger than females and weigh 37 to 90 kg (81 to 198 lbs) compared to 28 to 60 kg (62 to 132 lbs) for females.
Bears (family Ursidae) are mammals in the order Carnivora. Bears are classified as caniforms, or doglike carnivorans, with the pinnipeds being their closest living relatives. Although there are only eight living species of bear, they are widespread, appearing in a wide variety of habitats throughout the Northern Hemisphere and partially in the Southern Hemisphere.
Common characteristics of modern bears include a large body with stocky legs, a long snout, shaggy hair, plantigrade paws with five nonretractile claws, and a short tail. While the polar bear is mostly carnivorous and the giant panda feeds almost entirely on bamboo, the remaining six species are omnivorous, with largely varied diets including both plants and animals.
With the exceptions of courting individuals and mothers with their young, bears are typically solitary animals. They are sometimes diurnal, but are usually active during the night (nocturnal) or twilight (crepuscular). Bears are aided by an excellent sense of smell, and despite their heavy build and awkward gait, they can run quickly and are adept climbers and swimmers. Bears use shelters such as caves and burrows as their dens, which are occupied by most species during the winter for a long period of sleep similar to hibernation.
The Latin primas means "one of the first, excellent, noble" (nominative plural primates). The English singular primate was derived via back-formation from the Latin inflected form.
The Primates order is divided informally into three main groupings: prosimians, monkeys of the New World, and monkeys and apes of the Old World. The prosimians are species whose bodies most closely resemble that of the early proto-primates. The most well known of the prosimians, the lemurs, are located on the island of Madagascar and to a lesser extent on the Comoros Islands, isolated from the rest of the world. The New World monkeys include the familiar capuchin, howler, and squirrel monkeys. They live exclusively in the Americas. Discounting humans, the rest of the simians, the Old World monkeys and the apes, inhabit Africa and southern and central Asia, although fossil evidence shows many species existed in Europe as well.
Description
Males stand 3.64 meters (12 feet) tall at the shoulder and weigh 5455 kg (12,000 lbs), while females stand 3 meters (10 feet) and weigh 3636 kg to 4545 kg (8,000 to 11,000 lbs).
Teeth
Elephants have four molars; each weighs about 11 lbs and measures about 12 inches long. As the front pair wear down and drop out in pieces, the back pair shift forward and two new molars emerge in the back of the mouth. Elephants replace their teeth six times. At about 40 to 60 years of age the elephant no longer has teeth and will likely die of starvation, a common cause of death.
Their tusks are teeth; the second set of incisors become the tusks. They are used for digging for roots and stripping the bark off trees for food, for fighting each other during mating season, and for defending themselves against predators. The tusks weigh from 50-100 pounds and can be from 5 to 8 feet long. Both bulls and cows have tusks.
Species
Bush and Forest Elephants were formerly considered subspecies of the same species Loxodonta africana. However, they are nowadays generally considered to be two distinct species. The African Forest Elephant has a longer and narrower mandible, rounder ears, a different number of toenails, straighter and downward tusks, and considerably smaller size. With regard to the number of toenails: the African Bush Elephant normally has 4 toenails on the front foot and 3 on the hind foot, the African Forest Elephant normally has 5 toenails on the front foot and 4 on the hind foot (like the Asian elephant), but hybrids between the two species commonly occur.
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 there were substantial as recently as 1970, with an estimated population of 400,000; however, by 2006 the number had dwindled to about 10,000. The African elephant nominally has governmental protection, but poaching is still a serious issue.
Description
The basic crocodilian body plan is a very successful one; modern species closely resemble their Cretaceous ancestors of 84 million years ago. Mammals, too, have adapted to this body plan at least once in history. One ancestral whale family, the Ambulocetidae, were aquatic predators living in rivers and lakes, and they filled an ecological niche similar to the crocodilians.
Crocodilians have a flexible semi-erect (semi-sprawled) posture. They can walk in low, sprawled "belly walk," or hold their legs more directly underneath them to perform the "high walk." Most other reptiles can only walk in a sprawled position, and chameleons are the only modern reptiles with a more erect posture than crocodilians. The semi-erect posture makes it possible for some species to gallop on land if necessary. An Australian species can reach a speed of over 16 km/h while galloping on an irregular forest floor. Crocodilian ancestors, fast-moving terrestrial predators like the rauisuchians, actually had a fully erect posture, indicating that the sprawling and semi-erect posture of crocodilians evolved after they adapted to as semi-aquatic ambush predators. Their ankle bones, or tarsi are highly modified. Modern crocodilian locomotion is not a primitive trait, but a specialization for their semi-aquatic lifestyle.
Teeth and jaws
All crocodilians have, like Homo sapiens (humans), thecodont dentition (teeth set in bony sockets) but unlike mammals, they replace their teeth throughout life (though not in 'extreme' old-age). Juvenile crocodilians replace teeth with larger ones at a rate as high as 1 new tooth per socket every month. After reaching adult size in a few years, however, tooth replacement rates can slow to two years and even longer. Very old members of some species have been seen in an almost "edentulous" (toothless) state, after teeth have been broken and replacement slowed or ceased. The result of this is that a single crocodile can go through at least 3,000 teeth in its lifetime. Each tooth is hollow, and the new one is growing inside the old. In this way, a new tooth is ready once the old is lost. Crocodilians have a secondary bony palate that enables them to breathe when partially submerged, even if the mouth is full of water. Their internal nostrils open in the back of their throat, where a special part of the tongue called the "palatal valve" closes off their respiratory system when they are underwater. This way they can open their mouths underwater without choking. Most reptiles lack a secondary palate, but some skinks (family Scincidae) have evolved a bony secondary palate too, to varying degrees.
Crocodiles and gharials have modified salivary glands on their tongue (salt glands), which are used for excreting excess salt ions from their body. Alligators and caimans have them too, but here they are non-functioning. This indicates that at some point the common origin of the Crocodylia were adapted to saline/marine environments. This also explains their wide disribution across the continents (i.e. marine dispersal). Species like the saltwater crocodile (C. porosus) can survive protracted periods of time in the sea, and can hunt prey within this environment.
Crocodilians are often seen lying with their mouths open, a behavior called gaping. One of its functions is probably to cool them down, but since they also do this at night and when it is raining, it is possible that gaping has a social function too.
Internal organs
Crocodilians lack a vomeronasal organ (yet it is detectable in the embryo) and a urinary bladder.
Like mammals and birds and unlike other reptiles, crocodiles have a four-chambered heart; however, unlike mammals, oxygenated and deoxygenated blood can be mixed because of the presence of the left aortic arch. The right ventricle has two arteries leaving it; a pulmonary artery, which goes to the lungs, and the left aortic arch, which goes to the body, or systemic circulation. There is also a hole, the foramen of Panizza, between the left and right aortic arches. Because the left aortic arch goes directly to the gut, the shunting of oxygen depleted blood which is high in CO2 may serve to aid in creating stomach acid to assist in digesting bones from its prey. Their blood has been shown to have strong antibacterial properties. They have alveoli in their lungs and a unique muscular attachment to the liver and viscera that acts as a piston to breathing, separating the thoracic and abdominal cavities (similar to the diaphragm of mammals). Although tegu lizards have a primitive proto-diaphragm, separating the pulmonary cavity from the visceral cavity and allowing greater lung inflation, this has a different evolutionary history.
Crocodylians are known to swallow stones, gastroliths ("stomach-stones"), which act as a ballast in addition to aiding post-digestion processing of their prey. The crocodiylian stomach is divided into two chambers, the first one is described as being powerful and muscular, like a bird gizzard. This is where the gastroliths are found. The other stomach has the most acidic digestive system of any animal, and it can digest mostly everything from their prey; bones, feathers and horns.
The sex of developing crocodilians is determined by the incubation temperature of the eggs. This means crocodilians do not have genetic sex determination, but instead have a form of environmental sex determination which is based upon the temperature embryos are subjected to early in their development.
Sensory organs
Like all reptiles, crocodilians have a relatively small brain, but it is more advanced than in other reptiles. Among other things it has a true cerebral cortex.
As in many other aquatic or amphibian tetrapods, the eyes, ears, and nostrils are all located on the same plane. They see well during the day and may even have color vision, plus the eyes have a vertical, cat-like pupil which also gives them excellent night vision. The iris is silvery and a light reflecting layer of tapetum behind the retina greatly increases their ability to see in weak light and also makes their eyes glow in the dark. A third transparent eyelid, the nictitating membrane, protects their eyes underwater. However, they cannot focus under water, meaning other senses are more important when submerged under water.
While birds and most reptiles have a ring of bones around each eye which supports the eyeball (the sclerotic ring), the crocodiles lack these bones, just like mammals and snakes. The eardrums are located behind the eyes and are covered by a movable flap of skin. This flap closes, along with the nostrils and eyes, when they dive, preventing water from entering their external head openings. The middle ear cavity has a complex of bony air-filled passages and a branching eustachian tube. There is also a small muscle (which is also seen in gecko) next to or upon the stapes, the stapedius, which probably functions in the same way as the mammalian stapedius muscle does, dampening strong vibrations.
The upper and lower jaws are covered with sensory pits, seen as small, black speckles on the skin, the crocodile version of the lateral organ we see in fish and many amphibians. But they have a completely different origin. These pigmented nodules encase bundles of nerve fibers that respond to the slightest disturbance in surface water, detecting vibrations and small pressure changes in water, making it possible for them to detect prey, danger and intruders even in total darkness. These sense organs are known as DPRs (Dermal Pressure Receptors). While alligators and caimans only have them on their jaws, crocodiles have similar organs on almost every scale on their body. The function of the DPRs on the jaws are clear, but it is still not quite clear what the organs on the rest of the body in crocodiles actually do. They are probably doing the same as the organs on their jaws, but it seems like they can do more than that, like assisting in chemical reception or even salinity detection. The skin is covered with non-overlapping scales composed of the protein keratin (the same protein that forms hooves, skin, horns, feathers, hair, claws and nails in other tetrapods), which are shed individually. On the head the skin is actually fused to the bones of the skull. There are small plates of bone, called osteoderms or scutes, under the scales. Like the scales comprising the shell of a turtle, or the cross-section of a tree trunk, crocodile osteoderms have annual growth rings, and by counting them it is possible to tell their age. Osteoderms are found especially on the back, and in some species also on the belly. The rows of scutes cover the crocodile's body from head to tail, forming a tough protective armor. Beneath the scales and osteoderms is another layer of armor, both strong and flexible and built of rows of bony overlapping shingles called osteoscutes, which are embedded in the animal's back tissue. The blood-rich bumpy scales seen on their backs act as solar panels.
Their spool-shaped vertebrae in their ancestors went from being biconcave to having a concave front and a convex back in the modern forms. This made the vertebral column more flexible and strong.
They possess ribs of dermal origin restricted to the sides of the ventral body wall. The collar bone (clavicle) is absent.
The rhinoceros family is characterised by large size (one of the few remaining megafauna alive today) with all of the species capable of reaching one ton or more in weight; herbivorous diet; and a thick protective skin, 1.5–5 cm thick, formed from layers of collagen positioned in a lattice structure; relatively small brains for mammals this size (400–600g); and a large horn. They generally eat leafy material, although their ability to ferment food in their hindgut allows them to subsist on more fibrous plant matter, if necessary. Unlike other perissodactyls, the African species of rhinoceros lack teeth at the front of their mouths, relying instead on their powerful premolar and molar teeth to grind up plant food. The horns of a rhinoceros are made of keratin, the same type of protein that makes up hair and fingernails. Rhinoceroses have acute hearing and sense of smell, but poor eyesight. Most live to be about 60 years old or more. The word "rhinoceros" (ρινόκερος) is derived from the Greek words rhino, meaning nose, and kera, meaning horn; hence "horned-nose". The plural can be rhinoceros, rhinoceri, rhinoceroses, or rhinoceroi. The collective noun for a group of rhinoceros is "crash". The five living species fall into three categories. The two African species, the White Rhinoceros and the Black Rhinoceros, There are two living Rhinocerotini species, the endangered Indian Rhinoceros and the critically endangered Javan Rhinoceros and endangered Sumatran Rhinoceros.
An impala (Aepyceros melampus Greek aipos "high" ceros "horn" + melas "black" pous "foot") is a medium-sized African antelope. The name impala comes from the Zulu language. They are found in savannas and thick bushveld in Kenya, Tanzania, Mozambique, northern Namibia, Botswana, Zambia, Zimbabwe, southern Angola, northeastern South Africa and Uganda. Average mass for an Impala is approximately 75 kilograms. They are reddish-brown in color with lighter flanks, havewhite underbellies and a characteristic "M" marking on its rear. Males have lyre-shaped horns which can reach up to 90 centimeters in length. Impala are among the dominant species in many savannas. They can adapt to different environment by being grazers in some areas and browsers in others. They graze when the grass is green and growing and browse at other times. They will browse on formcsgaybs, shoots, bacon, seedpods and foliage.
A deer is a ruminant mammal belonging to the family Cervidae. A number of broadly similar animals from related families within the order Artiodactyla (even-toed ungulates) are often also called deer. Male deer grow and shed new antlers each year, as opposed to antelope, which are in the same order and bear a superficial resemblance to deer physically, but are permanently horned.Depending on their species, male deer are called stags, harts, bucks or bulls, and females are called hinds, does or cows. Young deer are called fawns or calves. Deer live in a variety of biomes ranging from tundra to the tropical rainforest. While often associated with forests, many deer are ecotone species that live in transitional areas between forests and thickets (for cover) and prairie and savanna (open space). The majority of large deer species inhabit temperate mixed deciduous forest, mountain mixed coniferous forest, tropical seasonal/dry forest, and savanna habitats around the world. Clearing open areas within forests to some extent may actually benefit deer populations by exposing the understory and allowing the types of grasses, weeds, and herbs to grow that deer like to eat. However, adequate forest or brush cover must still be provided for populations to grow and thrive.
