The Hippopotamus is the type genus of the family,Zoo,Alipore,India

• published: 07 Sep 2014
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The hippopotamus is the type genus of the family Hippopotamidae. The pygmy hippopotamus belongs to a different genus in Hippopotamidae, either Choeropsis or Hexaprotodon. Hippopotamidae are sometimes known as hippopotamids. Sometimes, the subfamily Hippopotaminae is used. Further, some taxonomists group hippopotamuses and anthracotheres in the superfamily Anthracotheroidea. Hippopotamidae are classified along with other even-toed ungulates in the order Artiodactyla. Other artiodactyls include camels, cattle, deer and pigs, although hippopotamuses are not closely related to these groups. Five subspecies of hippos have been described based on morphological differences in their skulls and geographical differences: H. a. amphibius – (the nominate subspecies) which stretched from Egypt, where they are now extinct, south up the Nile River to Tanzania and Mozambique H. a. kiboko – in Kenya in the African Great Lakes region, and in Somalia in the Horn of Africa. Broader nasals and more hollowed interorbital region H. a. capensis – from Zambia to South Africa, most flattened skull of the subspecies H. a. tschadensis – throughout Western Africa to, as the name suggests, Chad, slightly shorter and wider face, with prominent orbits H. a. constrictus – in Angola, the southern Democratic Republic of Congo and Namibia, named for its deeper preorbital constriction The suggested subspecies were never widely used or validated by field biologists; the described morphological differences were small enough that they could have resulted from simple variation in nonrepresentative samples.: Genetic analyses have tested the existence of three of these putative subspecies. A study examining mitochondrial DNA from skin biopsies taken from 13 sampling locations, considered genetic diversity and structure among hippo populations across the continent. The authors found low, but significant, genetic differentiation among H. a. amphibius, H. a. capensis, and H. a. kiboko. Neither H. a. tschadensis nor H. a. constrictus has been tested. Hippopotamuses are among the largest living land mammals, being only smaller than elephants and some rhinoceroses. Mean adult weight is around 1,500 kg (3,300 lb) and 1,300 kg (2,900 lb) for males and females respectively, very large males can reach 2,000 kg (4,400 lb) and an exceptional male weighting almost 2,700 kg (6,000 lb) has been reported. Male hippos appear to continue growing throughout their lives while females reach maximum weight at around age Different from all other large land mammals, hippos are of semiaquatic habits, spending the day in lakes and rivers. The eyes, ears, and nostrils of hippos are placed high on the roof of their skulls. This allows these organs to remain above the surface while the rest of the body submerges Their barrel-shaped bodies have graviportal skeletal structures, adapted to carrying their enormous weight, and their specific gravity allows them to sink and move along the bottom of a river. Hippopotamuses have small legs (relative to other megafauna) because the water in which they live reduces the weight burden. Though they are bulky animals, hippopotamuses can gallop at 30 km/h (19 mph) on land but normally trot. They are incapable of jumping but do climb up steep banks. Despite being semiaquatic and having webbed feet, an adult hippo is not a particularly good swimmer nor can it float. It is rarely found in deep water; when it is, the animal moves by porpoise-like leaps from the bottom.The testes of the males descend only partially and a scrotum is not present. In addition, the penis retracts into the body when not erect. The genitals of the female are unusual in that the vagina is ridged and two large diverticula protrude from the vulval vestibule. The function of these is unknown. The hippo's jaw is powered by a large masseter and a well-developed digastric; the latter loops up behind the former to the hyoid. The jaw hinge is located far back enough to allow the animal to open its mouth at almost 180°. On the National Geographic Channel television program, "Dangerous Encounters with Brady Barr", Dr. Brady Barr measured the bite force of an adult female hippo at 8,100 newtons (1,800 lbf); Barr also attempted to measure the bite pressure of an adult male hippo, but had to abandon the attempt due to the male's aggressiveness. Hippopotamus teeth sharpen themselves as they grind together. The lower canines and lower incisors are enlarged, especially in males, and grow continuously. The incisors can reach 40 cm (1.3 ft), while the canines reach up to 50 cm (1.6 ft). The canines and incisors are used for combat and play no role in feeding. Hippos rely on their broad horny lips to grasp and pull grasses which are then ground by the molars. The hippo is considered to be a pseudoruminant, it has a complex three- or four-chambered stomach but does not "chew cud". Source :http://en.wikipedia.org/wiki/Hippopotamus