| Hippopotamus | |||
|---|---|---|---|
| |||
| General information | |||
| Universe | Real Life | ||
| Aliases | Hippo Common hippopotamus/hippo River hippopotamus/hippo | ||
| Classification | Hippopotamus amphibius | ||
| Species type | Hippo | ||
| Homeworld | Earth | ||
| Environment | Lakes | ||
| Intelligence | They aren’t as smart as humans. While they are smart as rhinos, the hippos iq is actually lower than a rhinos so as a result the iq for a hippo is 55 | ||
| Biochemistry | Carbon-based | ||
| Biological information | |||
| Lifespan | Wild: 25-30 years Captivity: 40-50 years | ||
| Reproduction | Sexual, viviparous | ||
| Average height | 1.3-1.65 m (4'3.18"-5'4.96") at shoulder | ||
| Average weight | ♂: 1,500 kg (3,310 lb) ♀: 1,300 kg (2,870 lb) | ||
| Average length | 2.9-5.05 m (9'6.17"-16'6.82") including 35-56 cm (1'1.78"-1'10.05") tail | ||
| Locomotion | Quadrupedal | ||
| Feeding behavior | Omnivorous | ||
| Prey | Carrion Other hippos Grass | ||
| Predators | Other hippos Lions Crocodiles Hyenas (all for calves) Humans (illegally) | ||
| Lineage information | |||
| Related species | Lemerle's dwarf hippopotamus† Madagascar dwarf hippopotamus† Hippopotamus aethiopicus† Hippopotamus antiquus† Cretan dwarf hippopotamus† Hippopotamus gorgops† Hippopotamus kaisensis† Malagasy hippopotamus† Hippopotamus major† Maltese hippopotamus† Cyprus dwarf hippopotamus† Sicilian hippopotamus† Hippopotamus sirensis† Pygmy hippopotamus | ||
| Cultural information | |||
| Sociocultral characteristics | |||
| Scientific taxonomy | |||
| Planet | Earth | ||
| Domain | Eukaryota | ||
| Kingdom | Animalia | ||
| Subkingdom | Eumetazoa | ||
| Infrakingdom | Bilateria | ||
| Superphylum | Deuterostomia | ||
| Phylum | Chordata | ||
| Subphylum | Vertebrata | ||
| Infraphylum | Gnathostomata | ||
| Superclass | Tetrapoda | ||
| Class | Mammalia | ||
| Subclass | Theria | ||
| Infraclass | Placentalia | ||
| Superorder | Laurasiatheria | ||
| Order | Artiodactyla | ||
| Suborder | Whippomorpha | ||
| Superfamily | Hippopotamoidea | ||
| Family | Hippopotamidae | ||
| Subfamily | Hippopotaminae | ||
| Genus | Hippopotamus | ||
| Species | H. amphibius | ||
| Other information | |||
| Status | Vulnerable | ||
| Creator | God (debated) | ||
The hippopotamus (Hippopotamus amphibius), commonly shortened to "hippo" is a large semi-aquatic ungulate native to Africa.
Etymology[]
The Latin word hippopotamus is derived from the ancient Greek ἱπποπόταμος, hippopótamos, from ἵππος, híppos, "horse", and ποταμός, potamós, "river", meaning "horse of the river". In English, the plural is "hippopotamuses", but "hippopotami" is also used.
Characteristics and adaptations[]
Hippos are among the largest living land mammals, being only smaller than elephants and some rhinoceroses. Among the extant African megafauna, behind the two African elephant species, they average smaller than the white rhinoceros but are larger by body mass than the black rhinoceros and the giraffe. Hippos measure 2.90 to 5.05 m (9.5 to 16.6 ft) long, including a tail of about 35 to 56 cm (1.15 to 1.84 ft) in length and 1.30 to 1.65 m (4.3 to 5.4 ft) tall at the shoulder. Mean adult weight is around 1,500 kg (3,310 lb) and 1,300 kg (2,870 lb) for males and females respectively, very large males can reach 2,000 kg (4,410 lb) and exceptional males weighing 2,660 kg (5,860 lb), 3,200 kg (7,050 lb) and 4,500 kg (9,920 lb) (in captivity) have been reported. Male hippos appear to continue growing throughout their lives while females reach maximum weight at around age 25.
Hippos have barrel-shaped bodies with short legs and long muzzles. Their skeletal structures are graviportal, 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, hippos 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. Adult hippos move at speeds up to 8 km/h (5 mph) in water; typically resurfacing to breathe every three to five minutes. The young have to breathe every two to three minutes. The process of surfacing and breathing is unconscious: a hippo sleeping underwater will rise and breathe without waking up. A hippo closes its nostrils when it goes beneath the surface of the water. 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. 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 hippos 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°. A moderate folding of the orbicularis oris muscle allows the hippo to achieve such a gape without tearing any tissue. The bite force of an adult female hippo has been measured as 8.1 kN (1,800 lbf). Hippo 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 ft 4 in), while the canines reach up to 50 cm (1 ft 8 in). 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-chambered stomach but does not "chew cud".
Unlike most other semiaquatic animals, hippos have very little hair. The skin is 6 cm (2 in) thick, providing it great protection against conspecifics and predators. By contrast, its subcutaneous fat layer is thin. The animals' upper parts are purplish-grey to blue-black, while the under parts and areas around the eyes and ears can be brownish-pink. Their skin secretes a natural sunscreen substance which is red-coloured. The secretion is sometimes referred to as "blood sweat", but is neither blood nor sweat. This secretion is initially colourless and turns red-orange within minutes, eventually becoming brown. Two distinct pigments have been identified in the secretions, one red (hipposudoric acid) and one orange (norhipposudoric acid). The two pigments are highly acidic compounds. They inhibit the growth of disease-causing bacteria, and their light absorption peaks in the ultraviolet range, creating a sunscreen effect. All hippos, even those with different diets, secrete the pigments, so it does not appear that food is the source of the pigments. Instead, the animals may synthesise the pigments from precursors such as the amino acid tyrosine. Nevertheless, this natural sunscreen cannot prevent the animal's skin from cracking if it stays out of water too long. The secretion does help regulate the body temperature of the hippo and acts as an antibiotic.
A hippo's lifespan is typically 40–50 years. Donna the Hippo was one of the oldest living hippos in captivity. She lived at the Mesker Park Zoo in Evansville, Indiana, in the US until her death in 2012 at the age of 61. The oldest hippo recorded was called Bertha; she had lived in the Manila Zoo in the Philippines since it first opened in 1959. When she died in 2017, her age was estimated to be 65.
Distribution and status[]
Hippopotamus amphibius was widespread in North Africa and Europe during the Eemian and late Pleistocene until about 30,000 years ago. Archaeological evidence exists of its presence in the Levant, dating to less than 3,000 years ago. The species was common in Egypt's Nile region during antiquity but has since been extirpated. Pliny the Elder writes that, in his time, the best location in Egypt for capturing this animal was in the Saite nome; the animal could still be found along the Damietta branch after the Arab Conquest in 639. Reports of the slaughter of the last hippo in Natal Province were made at the end of the 19th century. Hippos are still found in the rivers and lakes of the northern Democratic Republic of the Congo, Uganda, Tanzania and Kenya, north through to Ethiopia, Somalia and Sudan, west to The Gambia, and south to South Africa.
Genetic evidence suggests that common hippos in Africa experienced a marked population expansion during or after the Pleistocene, attributed to an increase in water bodies at the end of the era. These findings have important conservation implications as hippo populations across the continent are currently threatened by loss of access to fresh water. Hippos are also subject to unregulated hunting and poaching. In May 2006, the hippo was identified as a vulnerable species on the IUCN Red List drawn up by the International Union for Conservation of Nature (IUCN), with an estimated population of between 125,000 and 150,000 hippos, a decline of between 7% and 20% since the IUCN's 1996 study. Zambia (40,000) and Tanzania (20,000–30,000) possess the largest populations.
The hippo population declined most dramatically in the Democratic Republic of the Congo. By 2005, the population in Virunga National Park had dropped to 800 or 900 from around 29,000 in the mid-1970s. The decline is attributed to the disruptions caused by the Second Congo War. The poachers are believed to be Mai-Mai rebels, poorly paid Congolese soldiers, and local militia groups. Reasons for poaching include the belief that hippos are harmful to society, as well as financial gain. However, as of 2016, the Virunga hippo population appears to have increased, possibly due to greater enforcement and cooperation between fishermen and park authorities. The sale of hippo meat is illegal, but black-market sales are difficult for Virunga National Park officers to track. Hippo meat is considered a delicacy in some areas of central Africa and the teeth have become a valued substitute for elephant ivory.
Invasive potential[]
In the late 1980s, Pablo Escobar kept four hippos in a private menagerie at his residence in Hacienda Nápoles, 100 kilometres (62 mi) east of Medellín, Colombia, after buying them in New Orleans. They were deemed too difficult to seize and move after Escobar's death in 1993, and hence left on the untended estate. By 2007, the animals had multiplied to 16 and had taken to roaming the area for food in the nearby Magdalena River. In 2009, two adults and one calf left their herd and, after attacking humans and killing cattle, one of the adults (called "Pepe") was killed by hunters under authorization of the local authorities.
When a photo of the dead hippo became public, it caused considerable controversy among animal rights groups both within the country and abroad, and further plans of culling ceased. Alternative methods have been considered, but they are unproven, or difficult and expensive. A wild male hippo was caught, castrated and released again, but it cost about US$50,000. As of 2020, there were no plans by the local government on managing the population, but further studies on their effect on the habitat have been initiated. Because of the fast-growing population, conservationists have recommended that a management plan needs to be rapidly developed. Scientists say these hippos are breeding voraciously and are an increasing menace so they must be culled.
In the U.S., Representative Robert F. Broussard of Louisiana introduced the "American Hippo Bill" in 1910 to authorize the importation and release of hippopotamus into the bayous of Louisiana. Broussard argued that the hippos would eat the invasive water hyacinth that was clogging the rivers and also produce meat to help solve the American meat crisis. The chief collaborators and proponents of Broussard's bill were Major Frederick Russell Burnham and Captain Fritz Duquesne. Former President Theodore Roosevelt backed the plan, as did the U.S. Department of Agriculture, The Washington Post, and The New York Times, which praised hippo meat as "lake cow bacon". The "American Hippo Bill" fell just short of being passed.
Behavior and ecology[]
Hippos differ from all other large land mammals, being of semiaquatic habits, and spending their days in lakes and rivers. They can be found in both savannah and forest areas. Proper habitat requires enough water to submerge in and grass nearby. Larger densities of the animals inhabit quiet waters with mostly firm, smooth sloping beaches. Male hippos may be found in very small numbers in rapid waters in rocky gorges. Hippos mostly live in freshwater habitats, however populations in West Africa mostly inhabit estuarine waters and may even be found at sea.
Most of a hippo's life occurs in the water. They spend up to 16 hours a day in water as a way to stay cool, and travel inland at dusk, sometimes up to 15 km (9 mi), to graze on short grasses, their main source of food. They spend four to five hours grazing and can consume 68 kg (150 lb) of grass each night. Like most herbivores, hippos will consume a variety of plants if presented with them, but their diet in nature consists almost entirely of grass, with only minimal consumption of aquatic plants. Because of their size and their habit of taking the same paths to feed, hippos can have a significant impact on the land across which they walk, both by keeping the land clear of vegetation and depressing the ground. Over prolonged periods, hippos can divert the paths of swamps and channels.
On occasion, hippos have been filmed eating carrion, usually near the water. There are other reports of meat-eating, and even cannibalism and predation. The stomach anatomy of a hippo is not suited to carnivory, and meat-eating is likely caused by aberrant behavior or nutritional stress.
Social spacing[]
Studying the interaction of males and females has long been complicated because hippos are not sexually dimorphic; thus, females and young males are almost indistinguishable in the field. Although hippos lie close to each other, they do not seem to form social bonds except between mothers and daughters, and they are not social animals. The reason they huddle close together is unknown. Hippos are territorial only in water, where the dominant bull also known as a "beachmaster" presides over a small stretch of river, on average 250 m (270 yd) in length and containing 10 females. The largest pods can contain over 100 hippos. Younger bachelors are allowed in a beachmaster's stretch, as long as they behave submissively toward him. The territories of hippos exist to establish mating rights. Within the pods, the hippos tend to segregate by sex. Bachelors lounge near other bachelors, females with other females, and the beachmaster is on his own. When hippos emerge from the water to graze, they do so individually.
Hippos mark their territory by defecation. While depositing the faeces, hippos spin their tails to distribute their excrement over a greater area. "Yawning" serves as a threat display. When fighting, males use their incisors to block each other's attacks and their large canines to inflict injuries. When hippos become over-populated or a habitat is reduced, males sometimes attempt infanticide, but this behaviour is not common under normal conditions. Incidents of hippo cannibalism have been documented, but this is believed to be the behaviour of distressed or sick hippos.
Hippos appear to communicate vocally, through grunts and bellows, and they may practice echolocation, but the purpose of these vocalizations is currently unknown. Hippos have the unique ability to hold their heads partially above the water and send out a cry that travels through both water and air; individuals respond above and under water. Hippos will also express threat and alarm with exhalations.
Reproduction[]
Female hippos reach sexual maturity at five to six years and have a gestation period of eight months. A study of endocrine systems revealed that female hippos may begin puberty as early as three or four years. Males reach maturity at around 7.5 years. A study of hippo reproductive behavior in Uganda showed that peak conceptions occurred during the end of the wet season in the summer, and peak births occurred toward the beginning of the wet season in late winter. This is because of the female's estrous cycle; as with most large mammals, male hippo spermatozoa are active year-round. Studies of hippos in Zambia and South Africa also showed evidence of births occurring at the start of the wet season. After becoming pregnant, a female hippo will typically not begin ovulation again for 17 months.
Mating occurs in the water, with the female submerged for most of the encounter, her head emerging periodically to draw breath. Female hippos isolate themselves to give birth and return within 10–14 days. Calves are born underwater at a weight between 25 and 50 kg (55 and 110 lb) and an average length of around 127 cm (4.17 ft), and must swim to the surface to take their first breaths. A mother typically gives birth to only one calf, although twins also occur. The young often rest on their mothers' backs when the water is too deep for them, and they swim under water to suckle. They suckle on land when the mother leaves the water.
Mother hippos are very protective of their young and may keep others at a distance, including the beachmaster who is the father of the calf. However, calves are occasionally left in nurseries which are guarded by one or a few adults. Calves in nurseries engage in playfights. Weaning starts between six and eight months after birth, and most calves are fully weaned after a year. Like many other large mammals, hippos are described as K-strategists, in this case typically producing just one large, well-developed infant every couple of years (rather than many small, poorly developed young several times per year as is common among small mammals such as rodents).
Interspecies interactions[]
Hippos coexist with a variety of large predators. Nile crocodiles, lions and spotted hyenas are known to prey on young hippos. However, due to their aggression and size, adult hippos are not usually preyed upon by other animals. Cases where large lion prides have successfully preyed on adult hippos have been reported but it is generally rare. Lions occasionally prey on adults at Gorongosa National Park and calves are sometimes taken at Virunga. Crocodiles are frequent targets of hippo aggression, probably because they often inhabit the same riparian habitats; crocodiles may be either aggressively displaced or killed by hippos. In turn, beyond cases of killing the seldom unguarded hippo calf, very large Nile crocodiles have been verified to occasionally prey on "half-grown" hippos—and based only on anecdotal evidence-possibly also adult female hippos. Aggregations of crocodiles have also been seen to dispatch still-living male hippos that have been previously injured in mating battles with other males.
As with fish and turtles on a coral reef, hippos occasionally visit cleaning stations and signal, by opening their mouths wide, their readiness for being cleaned of parasites by certain species of fishes. This is an example of mutualism, in which the hippo benefits from the cleaning while the fish receive food. Hippo defecation creates allochthonous deposits of organic matter along the riverbeds. These deposits have an unclear ecological function. A 2015 study concluded that hippo dung provides nutrients from terrestrial material for fish and aquatic invertebrates, while a 2018 study found that their dung can be toxic to aquatic life in large quantities, due to absorption of dissolved oxygen in water bodies.