Post by Vodmeister on Feb 28, 2014 0:13:22 GMT 5
Hippopotamus
The hippopotamus (Hippopotamus amphibius), or hippo, from the ancient Greek for "river horse" (
??), is a large, mostly herbivorous mammal in sub-Saharan Africa, and one of only two extant species in the family Hippopotamidae (the other is the pygmy hippopotamus). After the elephant and rhinoceros, the hippopotamus is the third-largest type of land mammal and the heaviest extant artiodactyl. Despite their physical resemblance to pigs and other terrestrial even-toed ungulates, their closest living relatives are cetaceans (whales, porpoises, etc.) from which they diverged about 55 million years ago. The common ancestor of whales and hippos split from other even-toed ungulates around 60 million years ago. The earliest known hippopotamus fossils, belonging to the genus Kenyapotamus in Africa, date to around 16 million years ago. Hippos are recognizable by their barrel-shaped torsos, enormous mouths and teeth, nearly hairless bodies, stubby legs and tremendous size. They are the third-largest type of land mammal by weight (between 1½ and 3 tonnes): the only heavier species on average are the white and Indian rhinoceroses, typically 1½ to 3½ tonnes, and the elephants, who are typically twice as big. The hippopotamus is one of the largest quadrupeds and, despite its stocky shape and short legs, it can easily outrun a human. Hippos have been clocked at 30 km/h (19 mph) over short distances. The hippopotamus is one of the most aggressive creatures in the world and, as such, ranks among the most dangerous animals in Africa. Nevertheless, they are still threatened by habitat loss and poaching for their meat and ivory canine teeth. The hippopotamus is semiaquatic, inhabiting rivers, lakes and mangrove swamps, where territorial bulls preside over a stretch of river and groups of five to 30 females and young. During the day, they remain cool by staying in the water or mud; reproduction and childbirth both occur in water. They emerge at dusk to graze on grasses. While hippopotamuses rest near each other in the water, grazing is a solitary activity and hippos are not territorial on land.
Northern Pacific Walrus
The walrus (Odobenus rosmarus) is a large flippered marine mammal with a discontinuous distribution about the North Pole in the Arctic Ocean and subarctic seas of the Northern Hemisphere. The walrus is the only living species in the Odobenidae family and Odobenus genus. This species is subdivided into three subspecies: the Atlantic walrus (O. r. rosmarus) which lives in the Atlantic Ocean, the Pacific walrus (O. r. divergens) which lives in the Pacific Ocean, and O. r. laptevi, which lives in the Laptev Sea of the Arctic Ocean.
Walruses occupy a nearly circumpolar region of the Arctic. Three distinct subspecific populations are recognized: 1) Atlantic (Odobenus rosmarus rosmarus), which lives in the eastern Canadian Arctic and Greenland east to Novaya Zemlya; 2) Pacific (O. r. divergens), living in the Bering Sea and adjacent Arctic Ocean; 3) Laptev Sea (O. r. laptevi), occupying the Laptev Sea, north of Siberia. Some taxonomists do not recognize the Laptev Sea population as a separate subspecies. Walruses prefer to inhabit areas with ice floes in the shallower regions near the coasts of Arctic waterways. Their seasonal migration patterns coincide with the changes in the ice. In the winter, walruses move south as the Arctic ice expands, and in the summer they retreat north as the ice recedes. This migration can cover distances of 3000 km. Individuals concentrate where the ice is relatively thin and dispersed in the winter. In the summer time, bulls may use isolated coastal beaches and rocky islets. Cows and young prefer to stay on ice floes in all seasons. While some outsized Pacific males can weigh as much as 2,000 kg (4,400 lb), the average weight of this species is about 1,300 kg (2,900 lb). The Atlantic subspecies weighs about 10–20% less than the Pacific subspecies.
The hippopotamus (Hippopotamus amphibius), or hippo, from the ancient Greek for "river horse" (
??), is a large, mostly herbivorous mammal in sub-Saharan Africa, and one of only two extant species in the family Hippopotamidae (the other is the pygmy hippopotamus). After the elephant and rhinoceros, the hippopotamus is the third-largest type of land mammal and the heaviest extant artiodactyl. Despite their physical resemblance to pigs and other terrestrial even-toed ungulates, their closest living relatives are cetaceans (whales, porpoises, etc.) from which they diverged about 55 million years ago. The common ancestor of whales and hippos split from other even-toed ungulates around 60 million years ago. The earliest known hippopotamus fossils, belonging to the genus Kenyapotamus in Africa, date to around 16 million years ago. Hippos are recognizable by their barrel-shaped torsos, enormous mouths and teeth, nearly hairless bodies, stubby legs and tremendous size. They are the third-largest type of land mammal by weight (between 1½ and 3 tonnes): the only heavier species on average are the white and Indian rhinoceroses, typically 1½ to 3½ tonnes, and the elephants, who are typically twice as big. The hippopotamus is one of the largest quadrupeds and, despite its stocky shape and short legs, it can easily outrun a human. Hippos have been clocked at 30 km/h (19 mph) over short distances. The hippopotamus is one of the most aggressive creatures in the world and, as such, ranks among the most dangerous animals in Africa. Nevertheless, they are still threatened by habitat loss and poaching for their meat and ivory canine teeth. The hippopotamus is semiaquatic, inhabiting rivers, lakes and mangrove swamps, where territorial bulls preside over a stretch of river and groups of five to 30 females and young. During the day, they remain cool by staying in the water or mud; reproduction and childbirth both occur in water. They emerge at dusk to graze on grasses. While hippopotamuses rest near each other in the water, grazing is a solitary activity and hippos are not territorial on land.Northern Pacific Walrus
The walrus (Odobenus rosmarus) is a large flippered marine mammal with a discontinuous distribution about the North Pole in the Arctic Ocean and subarctic seas of the Northern Hemisphere. The walrus is the only living species in the Odobenidae family and Odobenus genus. This species is subdivided into three subspecies: the Atlantic walrus (O. r. rosmarus) which lives in the Atlantic Ocean, the Pacific walrus (O. r. divergens) which lives in the Pacific Ocean, and O. r. laptevi, which lives in the Laptev Sea of the Arctic Ocean.
Walruses occupy a nearly circumpolar region of the Arctic. Three distinct subspecific populations are recognized: 1) Atlantic (Odobenus rosmarus rosmarus), which lives in the eastern Canadian Arctic and Greenland east to Novaya Zemlya; 2) Pacific (O. r. divergens), living in the Bering Sea and adjacent Arctic Ocean; 3) Laptev Sea (O. r. laptevi), occupying the Laptev Sea, north of Siberia. Some taxonomists do not recognize the Laptev Sea population as a separate subspecies. Walruses prefer to inhabit areas with ice floes in the shallower regions near the coasts of Arctic waterways. Their seasonal migration patterns coincide with the changes in the ice. In the winter, walruses move south as the Arctic ice expands, and in the summer they retreat north as the ice recedes. This migration can cover distances of 3000 km. Individuals concentrate where the ice is relatively thin and dispersed in the winter. In the summer time, bulls may use isolated coastal beaches and rocky islets. Cows and young prefer to stay on ice floes in all seasons. While some outsized Pacific males can weigh as much as 2,000 kg (4,400 lb), the average weight of this species is about 1,300 kg (2,900 lb). The Atlantic subspecies weighs about 10–20% less than the Pacific subspecies.
