Hippos – like their relatives the whales and dolphins – sleep mainly in water. They sleep completely submerged or with their nostrils just above the surface.
Where Do Hippos Sleep?
Hippos are semi-aquatic mammals. This means that they are designed to live more than half their life in water – just like sea lions and otters.
All land-based mammals can live on the land, of course. But hippos have had to evolve away from that by taking on some specialties for living and breeding in water. And one of them is sleeping underwater. Pretty nifty, eh?
Hippos have spent eons adapting to make the most of this watery habitat and we all have to sleep, right? So hippos have made sure they can do it with ease. They have self-sealing nostrils, flap-down ears, a heavy muscular body, and a breathing reflex that even works when they are asleep. Sleeping underwater or with just their nostrils poking out the top comes second nature – even to their calves.
The only animals that have gone one step further to sleeping underwater are their closest relatives – the cetaceans (whales, dolphins, and porpoises) who can even swim whilst being asleep?
Do Hippos Sleep At Night?
Hippos don’t actually sleep at night, no. Just like many species in Africa – they are most active at night – when it is cooler.
Hippos spend around 16 hours a day in the water – relaxing. They either sleep completely under the surface standing on the river bed; wallowing in the mud or basking on the shoreline. The less they do physically – the cooler they stay and the less energy they use. Being so huge (over 1300kg (2800lbs)) they need to look after themselves in the heat of the day.
Then, when the sun sets – they head out of the water and spend around 5-6 hours feeding on land. Back before sunrise.
How Long Do Hippos Sleep For?
As the days are so hot – hippos tend to spend the entire day relaxing – around 16 hours a day not doing much.
They snooze here and there, wander about and say hello to friends – and with groups of hippos sometimes numbering in the hundreds – social interaction can be a tiresome timewaster. Hippos can move very gracefully underwater when they want to – and so vary their location depending on the crowds and the temperature.
Wherever they choose – they try to do as little as possible. It isn’t clear how long they actually ‘sleep’ for in the human sense because they can rise to the surface and breathe before sinking again – all without waking up – so a moving hippo doesn’t necessarily mean they are awake. Without many enemies – hippos have no reason to be on edge while snoozing either, so can really catch some Zs.
Even though they aren’t often predated on by large carnivores, hippos may prefer to sleep in the water for safety (luckily, crocodiles won’t attack adult hippos). However, it is also possible that, due to water reducing the effect of gravity, that hippos can breathe more easily without the full weight of their body on their lungs. Hippos are immensely heavy and the feeling of weightlessness that water can give – could make being submerged just more comfortable.
Can a Hippo Chase and Catch Up to a Person Who is Running Away?
Running away from a hippo is no easy feat. These massive creatures can reach speeds of up to 30 mph, leaving little chance of outrunning a hippo on foot. With their massive jaws and agility in water and on land, it’s unlikely that a person could escape if pursued by one of these powerful creatures.
Why Do Hippos Spend All Day In Water?
If humans spent 16 hours a day in the bath – we would be all wrinkly and soggy – so how do hippos stay so solid-looking? It is all in the skin.
Human skin is very thin and porous, and skin reacts with the water itself making wrinkles. However, hippos have very thick skin – around 6cm (2 inches) thick to be precise. This skin is coated in a constantly excreted waxy red substance too so always looks shiny. Both these things combined stop the absorption of water and/or any skin changes from it – and also add a layer of protection from the sun.
It is still hot though where hippos live – and staying in the water (as anyone during a heatwave will confirm) feels great and helps keep your body cool. It can also help prevent sunburn for them as they don’t have protective hair or fur on their bodies – they are all skin. Secreting their waxy ‘sweat’ all over themselves as well as mud-bathing both help reduce skin damage from the sun.
It is also the best place to be if you are ridiculously heavy – as a hippo is. Being the weight of a family car can’t feel great on the legs – so even though hippos have strong, straight column-like legs to take the weight evenly – if they can stay off them for a few hours a day that has to be a good thing?
