1. Dolphins are mammals; they nurse their young from mammary glands.

2. Dolphins can swim up to 260 m. below the surface of the ocean, although they are mainly shallow divers.

3. Dolphins can stay up to 15 minutes under water although they usually stay only a few minutes diving.

4. Dolphins use a technique called echolocation to find food and navigate.

5. Dolphins are social beings which live in groups and cooperate among each other for activities like getting food and calf rising.

6. There are 32 species of ocean dolphins and 5 species of river dolphins.

7. The largest dolphin is the "killer whale" (orca), which can grow to 6.1 meters long.

8. The most known dolphin is the "bottlenose dolphin" which can grow to 2.5-2.8 meters.

9. Dolphins are warm-blooded and their internal temperature is around 36 degrees. To conserve this temperature they are surrounded by a thick layer of fat called "blubber" just below the skin.

10. The average botllenose dolphin brain weighs 1500-1600 grams, while average human brain weighs 1200-1300 grs. This is not a conclusive evidence of dolphin intelligence as many other factors might be the cause of intelligence according to scientists.

11. Dolphins can make a unique signature whistle that may help individual dolphins recognize each other or perform any other kind of communication still unknown.

12. Bottlenose dolphins can swim 5 to 12 kilometers per hour, although they can reach up to 32 km/h.