1. Dolphins

Dolphins are very intelligent animals!

Did you know that dolphins only sleep with half of their brain? Dolphins can even recognize themselves in the mirror! Dolphins are mammals that are found all over the world. Most of them live in shallow areas in warm and tropical waters,but five species actually live in rivers! Dolphins and whales sleep in an unusual way called "unhemispheric slow wave sleep,"It basically means that they sleep with only half of their brain. When a dolphin goes to sleep,it shuts down one hemisphere of its brain and closes the opposite eye. This allows the dolphin to monitor what's going on around them and to regulate its breathing.

2. Whales

Did you know that humpback whales don't eat for most of the year?Humpback whales in the Southern Hemisphere live off of their fat reserves for 5.5-7.5 months each year as they migrate from their tropical breeding grounds in the Antarctic to feed on krill. Do you know what the biggest animal that ever lived is? The Antarctic Blue whale is the biggest animal that ever roamed the earth weighing up to 200 tons (roughly 40 elephants)and reaching up to 30 meteres in length! Did you know that killer whales are actually dolphins? Orcas known as "Killer whales" are the largest members of the dolphin family.They are oceans top predators,eating a diverse range of marine species

3. Manatees

Did you know that manatees were once thought to be mermaids? In the 15th century sea creatures such as the krakens,mermaids,and sea serpents were popular in common folklore. The first recorded sighting of a manatee was in 1492 by American Christopher Colombus who thought the manatee he saw was a mermaid. Manatees don't have any natural predators making for a long lifespan of over 60 years or more! Manatees can eat a whopping 10 - 15 % of thier body weight each day! No wonder they are called sea cows!

4. Narwhals

The narwhal also known as the narwhale,is a medium sized toothed whale that posses a large "tusk"protruding canine tooth.It lives year - round in Arctic waters around Greenland,Canada and Russia.It is one of the two species of whale in Monodontidae long with the beluga whale.Did you know that narwhals change color as they age?Newborn narwhal are  speckled blue - green ,teens are blue - black,adults are speckled gray,old narwhal are almost completley white!Narwhals can live until they are 50 years old!The life span is supposed to be 30 - 40,though they have been  found to live up to 50 years of age!