Dolphins’ coloring sometimes helps them to be invisible in the water: looking down on them, their dark color merges with water, looking from underneath, light white and pink colors blends with light water in the background of the sun.

Dolphins are powerful swimmers. Their speed can reach about 5 - 10 km/hour, sometimes they can swim even with the speed of 37 km/hour, when they work hard. Their body shape helps them to swim fast, because it is shaped like a tube. The streamline makes the water flow over the dolphins’ body while they are swimming.

Dolphins can dive not deeper than 45 meters. Their dives do not last more than 3 – 4 minutes, but sometimes-oceanic animals can dive to depths of 60 meters for 15 minutes.

The front limbs of dolphins are called flippers and serve as measuring instruments of depth, turnings and brakes. The bones of flippers are similar to people’s bones of arms and legs. Dolphins have no hind limbs. Their tail is called flukes and has no bones. Dolphins’ flukes are used for swimming and flippers - for steering. Dolphins’ boneless dorsal fin on their back works like a rudder.

Dolphins have no sense of smell, but they have excellent sight and ear. Dolphins’ internal temperature is about 36 degrees, and they need to maintain their body heat in colder water. What helps dolphins to keep warm is thick layer of fat under their skin.

Dolphins breathe atmospheric air periodically rising to the surface. They have to be awake or semi – conscious to breathe. Therefore they sleep in a semi – conscious state at the surface periodically opening and closing their eyes. Dolphins are able to rest one half of their brain while the other is awake and can catch sight of some danger.

Dolphins can live over 30 years of age, sometimes there are cases when they die at 50 years of age. They start breeding at 9 -10 years old for females and 10 – 13 years in males. Dolphins mate all year round. Calves are born throughout the year, but mostly in spring and summer. The gestation period lasts 12 months. Calves stay with their mothers for about 5 years or more.

Dolphins live all over the world. Their native habitat varies from colder northern and southern waters to warm tropical waters. There are inshore and offshore populations. Inshore populations can be found in many seas, namely: the Red, Black and Mediterranean Seas and the Gulf of California. They also can be found in Atlantic and Pacific Ocean. Dolphins’ populations generally live in water less than 30 meters deep. The range of their habitats is presented by open coasts with a lot of surf as well as by bays, lagoons, big estuaries, reaches of rivers. Some populations are constant residents, others are transient, that undertake migrations each season. Dolphins’ way of life is gregarious. Group size is very different. Groups of inshore populations usually include 1-10 members. But offshore groups can number around hundreds. The size of groups may vary according to a certain season and many other factors: distance offshore, protection and others.