One study of hippos was not conducted in their natural environment, but in a zoo. In Yorkshire, England, Professor John Hutchinson and his students studied these animals at the Flamingo Land Zoological Garden.
They can fly
In the zoo, researchers decided to organize a race of hippos, filming them while running on high-resolution cameras, after which the footage was studied frame by frame to examine the movements of the legs of these mammals. To the surprise of scientists, the analysis of their running showed that these heavy and clumsy animals lift all four legs off the ground at the same time. For animals weighing up to two tons, such a feat would seem impossible, but it is.
A running hippo moves most of the time at a trot, synchronously moving its right front and left hind legs, and then its left front and right hind legs. This is also how elephants and other very large and heavy animals run. However, when hippopotamuses gallop to escape danger, they lift off the ground.
Scientists have found that during "flight", hippos are able to keep their bodies in the air for 15% of the time it takes them to run.
The researchers intend to conduct a similar study with very young individuals to see if they can "fly" more than their older compatriots.
The hippopotamus is no match for the pig.
Despite their serene appearance, hippos are not very peaceful or friendly creatures. They sometimes attack boats if disturbed while they are resting in the water. Every year
more people die in Africa from the terrifying teeth of hippos. A team of scientists from the University of Jean Monnet-Saint-Etienne, led by Frenchman
Nicolas Matevon, found in the field that these animals are able to recognize the voice of other hippos.
They react differently when they hear the voice of an individual from their own pack, an individual from a different family but living in the same lake, or the voice of another group from a distant area. The researchers recorded the cries of hippos from different families and gave them to the test group to listen to over a loudspeaker. The more "alien" the cry seemed, the more aggressive the animals became.
For more than 200 years, biologists have argued over which family these mammals belong to. The Greeks hypothesized that hippos could have descended from the ancestors of horses; they called them "river horses". However, the analysis of their teeth allowed later scientists to include hippos in the pig family, which remained the most relevant for a long time.
A recent study conducted by scientists at the University of Berkeley in California has disproved the theory of the origin of hippos from the pig family, the hypothesis they put forward was unexpected: hippos are the closest living relatives of whales.
The fact is that back in 1985, a molecular analysis of the blood of two animals was carried out, which revealed a strong mutual connection between proteins, on which the hypothesis of Californian biologists was based. There is only one thing that confuses scientists.
The first whale fossil is dated to be about 53 million years old, and the first hippopotamus skeleton discovered is 40 million years younger. And there's not much in the way of external similarities between these mammals. Then the researchers traced the origin of these two animals to a common ancestor who liked to swim.
It turned out that this ancient progenitor lived between 50 and 60 million years ago, and two groups of animals evolved from it: the ancestors of cetaceans, which in the process of
evolution lost their legs and became completely aquatic, and pig-like animals called anthracotherians. When they became extinct 2.5 million years ago, hippos were their only descendants. But even here, scientists are still divided.