About 21 of these species are found in Australian waters and most of them around Victoria's coastline. The largest of the dolphins is the bottlenose dolphin which grows to over 4 meters and can weigh over 650 kg. The smallest is Hector's dolphin at about 1.5 meters and 60 kg. Their teeth are sharp and peg-like in shape and function for grabbing prey, not for biting out chunks or chewing. Dolphins can be aged by counting the growth rings in their teeth just like in a tree.
Dolphins live in world of sound.
They use sounds to communicate and each animal has its own signature whistle which acts like a name. Dolphins do have a large brain and are superbly adapted to their environment. In captivity dolphins have been taught a type of language and can understand complex instructions, just like a dog or horse. Dolphins live in such a different environment than ours that trying to compare intelligence to other species is not really useful.