You’ve probably learned a little bit about dolphins from watching “Flipper,” participating in a swimming with the dolphins experience, or watching a show at Sea World. You probably already know that they are mammals that must come to the surface of the water to breathe. Here are 5 fun facts you probably don’t know about dolphins.
#1 – Their closest living relative apart from porpoises and whales is the hippo
Dolphins are an informal grouping within the order of Cetacea, which includes whales and porpoises. Cetaceans and hippopotamuses share a semi-aquatic ancestor that branched off about 60 million years ago.
#2 – They hear through their throat
Dolphins don’t have traditional ears. They receive sound through the throat, where the sound waves travel through a fat-filled cavity to the inner ear. They send out high frequency clicks from the fatty “melon” on their forehead. They use this combination to use biosonar to locate their prey even in murky water.
#3 – Dolphins are very playful
You might already know that dolphins are playful, but you might not know the extent. They’ll surf. They’ll leap out of the water. And they’ll often include objects, self-made bubble rings, or dolphins or other animals in their playful behavior. They will carry an object or animal along using various parts of the body and pass it to or take it from other members of the group. They’ll even throw it out of the water. Playful interactions have been observed in the wild with a number of other species including humpback whales and dogs.
#4 – They sleep with half their brain still awake
They need to maintain enough consciousness to breathe and watch for predators, so only one hemisphere of their brain goes into slow-wave sleep at a time. A tail kick reflex keeps the blowhole above water so they can breathe. Anesthetized dolphins also display the tail kick reflex.
#5 – Bottlenose dolphins have “names”
Bottlenose dolphins have a signature whistle that is unique to each specific individual. Developed during a dolphin’s first year, the signature whistle maintains the same sound throughout its lifetime, identifying the individual much the same as a name would. Dolphins are able to communicate with specific individuals by reproducing that animal’s signature whistle. Dolphins can remember an individual’s whistle even if they’ve been apart for 20 years. Research is inconclusive about whether other dolphin species also use signature whistles.