HipoppotamusPosted on June 26, 2018 - Last modified: August 5, 2018
hippopotamus (Danio rerio) is an large mammal semi-aquatic, which the Greeks called a "river horse," on a typical day they spend up to 16 hours a day submerged in rivers and lakes to keep their huge bodies cool under the hot African sun. They are graceful in the water, good swimmers, and can hold their breath underwater for up to five minutes. However, they are often large enough to simply walk or stand on the bottom of the lake, or lie in the shallow water. Their eyes and nostrils are located high on their heads, allowing them to see and breathe while mostly submerged in water.
They also live on the coast and secrete a red oily substance, which gave rise to the myth that they sweat blood. The liquid is actually a skin moisturizer and sunscreen that can also provide protection against germs.
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The hippopotamus is the third largest living land mammal, after elephants and white rhinos. The leg of a hippopotamus has four webbed toes that spread out to distribute weight evenly and therefore support it properly on land.
The greyish body has very thick fur without hair. The hippo has neither sweat nor sebaceous glands, and relies on water or mud to keep cool. However, it secretes a viscous red liquid, which protects the animal's skin from the sun and is possibly a healing agent. The flat, paddle-like tail of the hippopotamus is used to spread droppings, marking the boundaries of the territory and indicating the status of an individual.
At sunset, they leave the water and travel overland to graze. They can travel up to 10 km in one night, along single-lane roads, to consume about 36 kilos of grass. Considering its enormous size, a hippo's food consumption is relatively low. If threatened on land, they can run into the water, they can match the speed of a human over short distances.
Two species of hippos are found in Africa. The great hippopotamus, found in East Africa, is found south of the Sahara. The other much smaller species is the pygmy hippopotamus. Limited to very restricted ranges in West Africa, it is a shy and solitary forest dweller and is now rare.
Hippos were once more widely distributed, but now live in eastern, central and southern sub-Saharan Africa, where their populations are in decline.
The hippo is an animal herbivore, so it eats mainly plant foods to feed its large structures. Grass and fallen fruit form the diet of wild hippos, while hippos that live in zoos often eat vegetables and shrubs.
Hippos prefer to graze in the grass near water beds. Due to the shape of their teeth, they look for short, clipped patches of vegetation that they can easily chew on. They can consume fruit if they fall to the ground. With their keen ears, they can hear the sound of falling fruit.
In captivity, a hippo eats a combination of plants, including hay, alfalfa, and lettuce. On special occasions, hippos can receive pumpkins or melons as gifts. Zoos provide hippos and other herbivores with special vegetarian pellets that meet their nutritional needs.
Hippos don't move around much during the day, so they only consume about 45 kilos of food per night. This may sound like a lot, but when you compare it to its size, it comes out to just 1 percent or 1,5% of the individual hippo's body weight. By comparison, larger cattle eat 2.5% of their body weight daily.
On rare occasions, the wild hippo will eat meat or insects. Usually this is due to a shortage of grasses, vegetation and fruits that make up their regular diet, for example during a drought. Hippos can chew on aquatic plants, but this flora does not constitute a significant part of their diet.
Young calves are vulnerable to crocodiles, lions, and hyenas. Attacks on small boats are believed to be anti-predatory behavior, with hippos mistaking the boats for crocodiles.
Newborns of the hippopotamus weigh 45 kilograms on average at birth and can suckle on land or underwater by covering their ears and nostrils. Each female has only one young every two years. Shortly after birth, mother and calf learn to protect themselves against crocodiles, lions, and hyenas.
In the wild, females mature sexually between 7 and 15 years, and males mature a little earlier, between 6 and 13 years. However, in captivity, members of both sexes can become sexually mature at the age of 3 and 4 years.
Males monopolize areas in the river as mating territories for 12 years or more. Subordinate males are tolerated if they do not attempt to reproduce. Females cluster in these areas during the dry season, which is when most mating takes place.
Confrontations can rarely break out when strange males invade territories in the mating season. Most of the assaults are noise, splashes, bluff charges, and a yawn of the teeth, but opponents can participate in combat by cutting up each other's flanks with their lower incisors. Wounds can be fatal despite thick skin.
Adjacent territorial males will stare at each other, then turn around and, with their backs out of the water, flip their feces and urine in a wide arc with a rapid flick of their tails. This routine screen indicates that the territory is occupied. Both territorial and subordinate males form manure piles along trails leading inland, which probably function as olfactory cues (scent markers) at night. Hippos recognize individuals by their scent and sometimes follow each other from nose to tail on night walks.
Fertilization results in a single calf, born after a gestation of eight months. The hatchling may close its ears and nostrils to nurse underwater; it can climb on its mother's back above the water to rest. She begins to eat grass every month and is weaned at six to eight months of age.
Females produce a calf every two years. sometimes they bond with their young for a few years. Longevity is up to 61 years in captivity, but rarely more than 40 years in the wild.
State of conservation
The IUCN Assessment described this animal as Vulnerable (VU), as the population experienced significant declines in the mid-1990s and early 2000s. The most recent population estimates suggest that, in the past 8 years since the last assessment, common hippo populations have been largely stable.
The 2008 Red List Assessment estimated hippo populations to be roughly 125.000 and 148.000, and that half of the 29 countries where common hippos were found reported declines.
The current assessment yields a lower population estimate of the order of 115.000-130.000 hippos. Although hippo populations have stabilized in some countries, hippo population declines continue to be seen in many countries. The increasing and incessant threats of habitat loss and unregulated hunting are major challenges to the viability and persistence of the hippo population.
In 1990 an animated series starring hippos became popular, The Moomins, based on folk tales and comics by the Finnish brothers Tove and Lars Jansson.