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Hippopotamus amphibius

(Common Hippopotamus, Hippopotamus, Nile Hippo, River Hippopotamus)

Overview

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Vulnerable
Threat status

Interesting Facts

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Common Names

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Click on the language to view common names.

Common Names in Dutch:

Nijlpaarden

Common Names in English:

Common Hippopotamus, Hippopotamus, Hippopotamus Linnaeus, 1758, Nile Hippo, River Hippopotamus

Description

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Physical Description

Species Hippopotamus amphibius

Hippopotamus is Greek for "river horse." The hippo is the second or third largest land animal, depending on which rhino one is considering, and by far the largest river dweller. A mature bull is about 13 feet long, nose to tail, and measures five feet high at the shoulder .

Hippos have a thin epidermis , and the rate of water loss through the skin in dry air is several times greater than in other mammals. Hence, the hippo must stay in the water or in a very humid habitat to prevent dehydration .

Hippos have stubby little legs that could not possibly support its great bulk, over an average of forty years or so, without the buoyancy of water to relieve the burden.

They have a set of massive, razor sharp tusks found in the corners of the jaw and hidden away inside the folds of their fatty lips . The two tusks of the lower jaw can grow to a foot or more. Sharp incisors also line both jaws .

Habitat

Hippos arrive at the water pool before sunrise and leave after dark. In the grass the hippos spread out and graze alone, except for females and their calves , who stay close together most of the night. Hippos will travel great distances to establish their natural grazing area.

Typically found at an altitude of 0 to 2,163 meters (0 to 7,096 feet).Mean = 668.170 meters (2,192.159 feet), Standard Deviation = 552.350 based on 75 observations. Altitude information for each observation from British Oceanographic Data Centre.

Biome: Terrestrial ; Freshwater

Ecology: As its name suggests, the hippopotamus is an amphibious creature, which spends the day in water and emerges at night to feed . The hippopotamus uses the water only as a retreat and it does not eat aquatic vegetation to any extent. Open water is not essential and the animal can survive in muddy wallows but it must have access to permanent water to which it can return in the dry season . The essential factor is that the skin must remain moist for it will crack if exposed to the air for long periods. The skin physiology is complex and not fully understood but is clearly adapted for an amphibious existence. A curious feature is the red secretion from modified sweat glands , which is thought to have an antibiotic function. The water body must be large enough to accommodate a number of animals for the hippopotamus is highly gregarious when resting by day. The social habits of the species have been studied by Klingel (1991), who found that the "schools" are unstable groups of females and bachelors. The social system is based on mating territoriality . Common hippos are gregarious, social, polygynous animals. Females become sexually mature between the ages of 7 and ndash;9, and males 9 and ndash;11. Females typically bear a single offspring every other year as lactation can extend for 18 months. Territorial males monopolize a length of the shoreline of the river or lake but tolerate bachelors within the territory provided they behave submissively. Non-breeding males also settle outside territorial areas, especially seasonal wallows. Fights for the possession of a territory can be fierce and the animals may inflict considerable damage on each other with their huge canines but minor conflicts are usually settled by threat displays, of which the "yawn" is the most conspicuous . Territorial males do not normally fight each other and severe fights usually occur only when a bachelor challenges a territorial male for control of its territory. There is little association between animals when they are feeding at night, except between females and their dependent young, and the males do not then behave in a territorial fashion. The male hippopotamus, rarely the female, spreads its dung by wagging its tail vigorously while defecating, both in the water and on land , where it is thought to have a signalling rather than a territorial function. The dung piles may serve for orientation. Vocalizations take the form of complex bellows and grunts , which presumably have a signaling function. Sounds may be made either on land or in the water and may be transmitted simultaneously through air and water. This is the only known case of amphibious calls in a mammal.It is probable that the need to avoid the direct rays of the sun has determined the nocturnal feeding habits of the animal. It leaves its wallow soon after sunset and spends the night grazing on short grass swards for up to several kilometers from water. These swards, which are kept short by the activities of the hippopotamus, are known as hippo lawns. Although the hippopotamus grazes every night, except for mothers with very young calves , there are usually animals present in the water all night, as some return after a few hours and others leave later. The animal feeds by plucking the grass with its wide, muscular lips and passing it to the back of the mouth to be ground up by the molars. The front teeth (incisors and canines) play no part in feeding. The amount of food ingested is small relative to the size of the animal but its resting habits by day reduce its energetic demands. The stomach is a complex four-chambered structure with a ruminant type digestion although the animal does not chew the cud .The ecological requirements for hippopotamus, therefore, include a supply of permanent water, large enough for the territorial males to spread out, and adequate grazing on open grassland within a few kilometers of the daytime resting sites. (Ref. 95987)

List of Habitats : 1.6 Forest - Subtropical/Tropical Moist Lowland 1.7 Forest - Subtropical/Tropical Mangrove Vegetation Above High Tide Level 1.8 Forest - Subtropical/Tropical Swamp 2.2 Savanna - Moist 3.6 Shrubland - Subtropical/Tropical Moist 4.6 Grassland - Subtropical/Tropical Seasonally Wet/Flooded 5.1 Wetlands (inland) - Permanent Rivers/Streams/Creeks (includes waterfalls ) 5.2 Wetlands (inland) - Seasonal/Intermittent/Irregular Rivers/Streams/Creeks 5.3 Wetlands (inland) - Shrub Dominated Wetlands 5.5 Wetlands (inland) - Permanent Freshwater Lakes (over 8ha) 5.6 Wetlands (inland) - Seasonal/Intermittent Freshwater Lakes (over 8ha) 5.7 Wetlands (inland) - Permanent Freshwater Marshes/Pools (under 8ha) 5.8 Wetlands (inland) - Seasonal/Intermittent Freshwater Marshes/Pools (under 8ha) 5.13 Wetlands (inland) - Permanent Inland Deltas 5.14 Wetlands (inland) - Permanent Saline, Brackish or Alkaline Lakes 5.15 Wetlands (inland) - Seasonal/Intermittent Saline, Brackish or Alkaline Lakes and Flats 5.16 Wetlands (inland) - Permanent Saline, Brackish or Alkaline Marshes/Pools 5.17 Wetlands (inland) - Seasonal/Intermittent Saline, Brackish or Alkaline Marshes/Pools 9.10 Marine Neritic - Estuaries 13.4 Marine Coastal/Supratidal - Coastal Brackish/Saline Lagoons/Marine Lakes 13.5 Marine Coastal/Supratidal - Coastal Freshwater Lakes

Biology

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Diet

An adult hippo eats more than 150 pounds of grass a night. These grazers tear up grass not with their teeth but with their lips . In the zoo, they eat zoo ration , alfalfa hay, trace minerals, and water free choice .

Reproduction

Hippos have a low mortality rate, and both males and females reproduce into old age. Longevity is 40 years or so. Females usually have their first calf at about 10 years of age.

A single calf is born at a time, rarely two, with a gestation period of 227-240 days. The calf weighs 60-100 pounds at birth and measures up to 3 feet long. Calves are sometimes born underwater and must swim to the surface for their first breath of air . They also nurse underwater some of the time. Young hippos occupy most of their time in the water standing on the backs of their mothers. Otherwise, the effort to keep afloat would wear them out.

Behavior

Although hippos might look docile, they are probably the most dangerous African animal. They are not only aggressive and easily enraged, but they are also very unpredictable. On land , this 1-3 ton animal, over a short haul , can easily outrun a man.

Lions, leopards, hyenas, or wild dogs will occasionally take a baby . Only man hunts the adult .

The adult hippo's only real enemy (other than man) is his pool mate. They bite , maim, and kill each other. The bulls fight over females in breeding season and quarrel over water space at all times, especially in dry season . When seen yawning , a hippo may actually be threatening another hippo.

Hippos can stay totally submerged for up to six minutes and, having a high specific gravity, they can easily walk or run along the bottom during a dive. When submerged, they close the valves of their nostrils and press their ears flat against the sides of their heads . The heart rate slows down , giving it more time underwater. When it surfaces, it is usually with a loud hiss, a snort, or distinctive grunt that sounds like a blast from a tuba.

At the river , lake or stream , the herd gathers in "schools" comprised of 20 or more. The configuration depends on the available space or depth of water, as the hippo needs to submerge itself up to its ears, protruding eyes, and nostrils (all conveniently placed on top of its head, like a crocodile or a frog ) without exposing much else to the hot African sun. The hippo expends far less energy during the day in the water than he would on land.

Taxonomy

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Notes

Name Status: Accepted Name . Latest taxonomic scrutiny: 22-Apr-2004.

Similar Species

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Members of the genus Hippopotamus

There are approximately 24 species in this genus:

H. aethiopicus · H. amphibious (Hippopotamus) · H. amphibius (Common Hippopotamus) · H. amphibius amphibius · H. amphibius capensis · H. amphibius kiboko · H. amphibius tschadensis · H. antiquus · H. behemoth · H. creutzburgi · H. creutzburgi creutzburgi · H. gorgops · H. imaguncula · H. kaisensis · H. lemerlei (Madagascan Dwarf Hippopotamus) · H. liberiensis · H. madagascariensis (Madagascan Pygmy Hippo) · H. major · H. minutus · H. pentlandi · H. ponderosus · H. protoamphibius · H. sirensis · H. sivalensis

Bibliography

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More Info

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Notes

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Contributors

Data Sources

Accessed through GBIF Data Portal November 17, 2007:

Identifiers

Footnotes

Last Revised: September 02, 2008