Hippos, Rotund African “River Horses”

Please consider the images to be copyrighted and use only with my permission.
Thank you. DEClapp.

The hippopotamus is a chunky animal with a wide body and short legs. They can weigh up to two tons and big males often more than that. An average weight might be about 3300 pounds (about 1500 kilograms). They are chunky; have short legs, a short neck, a big head, with a cylindrical body and an arched back. One of the in-the-field characteristics of hippo country are the neat little trails they use to get from the water to the grazing areas. The chubby body and short legs means that they cannot step their own toes or cross their legs, nor can they trample a wide swath as they walk. The left legs make a narrow trail and the right legs make a separate narrow trail. For a big animal they seem to walk delicately through the bush. The two lane trails are obvious once you know what to look for.

They also make exit trails from the water where they spend the day. They leave the river via the same path each evening and break down the sandy edges of the river bank. These sloping trails to and from the water are what the migrating wildebeest and zebras use when crossing rivers. They descend along the hippo paths and hopefully they find another path, on the far side, that offers them an escape from the river (and the hungry crocodiles that just wait for the migration). The migratory beasts don’t plan well and sometimes get stuck against the far bank; sometimes with dire consequences.

Hippos spend the day in water. They actually produce a viscous fluid that protects them from the sun, but staying in water is most helpful in keeping their body temperature even. They are in smallish family groups for the most part. However, in the dry seasons when the casual water dries up they will be found in larger groups in the remaining permanent water holes. Most of the time there is a dominant male and a group of females with a scattering of younger animals. The water is usually filthy and quite fetid as these large animals process a great deal of vegetation and have rather casual bathroom habits. You would never drink from a hippo pool.

Hippos are quite dangerous especially in the dark. They travel long distances from the water and they can panic if they feel separated from the water. Most people are hit by the large and heavy head of the hippo or are trampled as the hippo bolts for the water. It is an unpredictable animal, and very widespread, making it one of the most dangerous animals on the continent.

2018 serengeti hippo baby
Babies are quite small and can be rolled and drowned when the males cause a rumpus in the loafing pod. Thus the females move off from the group to give birth and then keep the babies away from the group until they master the holding-your-breath aspect of living in the water. Once capable they will be able to hold their breath for 5-6 minutes and often drop to the bottom and slowly bounce back to the surface. They are generally in very shallow water. The female above had just given birth to the tiny baby just off her right jowl. The baby was able to move in the water but stayed within a couple of feet of the mother the whole time I watched it. It will be a few weeks before the babe is brough back to pod.
Once they can swim and hold their breath the young join the main group. But like most creature they enjoy the company of others within their own age bracket. When the older youngsters wander about they are often with others of their own age class and somewhat separate from the bigger adults.
There are some places where the river banks are not sandy but quite rocky and don’t slope very much. In these areas the hippos are very careful when coming and going. They walk very slowly and are sure of their footing along the way. These two just came down the sandy path in the upper left and then carefully picked their way across the rock shelves and finally back to their spot; a shallow bay along the river’s edge. This image is from the Rufiji River in the Selous NP in southern Tanzania.

Hippos have an even number of toes; four on each foot. That is important as grazing animals, most land mammals, are divided into two groups – those with an even number of toes and those with an odd number of toes. The even-toed are the Artiodactyla and the odd-toed are the Perissodactyla. The latter group, odd-toed, contains the horses, rhinoceroses, and tapirs who balance on their hoof-covered, third digit. The former group, even-toed, contains the hippo, deer, goats, camels, pigs, bison, giraffe, antelope, and llamas and they walk on their third and fourth toes, often fused. This divergence in hand/foot structure goes back about 53 million years when the even-toed animals first appear in the fossil record. By the way, the word ungulate isn’t really a good taxonomical word; it usually refers to hoofed animals although it is often used to refer to the cud-chewing animals. And further by the way; a hoof is merely a modified toenail.

Bob-S.Africa1 121
This is a very nice picture of a rather significant hippo behavior; however odd we may think it to be. When leaving the water the male will defecate on a shrub or bush and splatter the feces with his short flat tail. This will serve as an olfactory memo to other hippos that he is still in residence and still in charge. Scent is an important part of the world beyond humans. Reproductive readiness is usually announced by pheromones and discovered by the sensitive noses of the males; female lions, elephants, gazelles, and many other animals announce their health and state of fertility by leaving scent clues for the males

Like elephants, hippos are declining rapidly because of poaching. The large teeth are sought after for carving and for a wrongly presumed to have a medicinal value. Loss of wetlands and grazing habitat (mostly to farming) also is having an impact.

The hippo’s nearest evolutionary relative is an aquatic or semi-aquatic creature from which evolved the cetaceans and the hippos. The shared relative existed about 60 million years ago and the splitting of the ancestor into the two groups (whales and hippos) happened about 54 million years ago. You might Google Pakicetus to get a look at one of the earliest forms that is in the whale/dolphin/porpoise (cetacean) line. The hippo’s evolutionary relationship with cetaceans has been solidified with blood protein analysis and even more recent DNA work.

Tanzania 2018 hippo – Version 2
Hippos are large, territorial, unpredictable, and quite dangerous when on land. In the water they are rarely a problem as they can easily sink and scoot away. But on land they can be quick and intent. Note that the eyes, the ears, and the nostrils have moved to the top of the head (over tens of thousands of generations – not in each animal) allowing the animal to breath, see, and hear while almost all the body remain under the water. It is a bit like being able to use a snorkel, a periscope, and sonar while remaining hidden. Neat, huh?


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