Dolphins are really small, toothed-whales and like us are intelligent mammals, breathing air, being warm-blooded and giving birth to live young that are fed milk. All whales belong to the order Cetacea ("Set-ach-ya"). The great whales such as the blue and humpback whales use baleen plates instead of teeth to filter krill out of the plankton and belong to the suborder, Mysteceti. Dolphins are the smallest members of the suborder Odontoceti, or toothed whales, which also includes the giant sperm and killer whales. There are 31 species of true dolphins. About 21 of these species are found in Australian waters and most of them around Victoria's coastline. Most dolphins have the "typical" streamlined shape, with a pointed beak and prominent dorsal fin. The largest of the dolphins is the bottlenose dolphin which grows to over 4 metres and can weigh over 650 kg. The smallest is Hector's dolphin at about 1.5 metres and 60 kg. All dolphins are "homodonts" which means that all their teeth are the same, not having molars and incisors like most mammals. 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. Porpoises are not the same as dolphins. Whilst "dolphin-like", they have a rounded head without the typical dolphin beak, and a very small dorsal fin. Their teeth are flattened in cross-section, unlike the dolphin's round teeth. Porpoises have never been seen in Australian waters. The dorsal fin (on the back) stabilises the dolphin, flippers assist in balance and direction, while the tail flukes provide driving power. Calves receive assistance by swimming in their mother's slip-stream. Dolphins have adapted to swimming in the marine environment by streamlining their bodies, through the loss of hair and hind limbs, and with the movement of their nostril (blow hole) to the top of the skull. Calves are born tail first and are assisted to the surface by mother and 'aunts'. Suckling lasts 12 to 18 months and the milk, which is rich in calcium, phosphorous, fats and proteins, is squirted voluntarily from the mother into the calf's' rolled up tongue. The calf will feed frequently in short bursts which last only seconds. By six months the calf is eating solids. After one year the calf's size will have increased to approximately 7 times its birth weight. The blowhole has to be deliberately opened by muscles when the dolphin surfaces to breathe. They give a small puff of air just before they surface to clear the water away before they inhale. Dolphins can exchange most of their lung's contents during a breath, many times more efficient than we humans. Dolphins can see well both in and out of the water. Touch is well developed all over the skin, with highly sensitive regions around the blow hole and on the tongue. A high level of physical contact between dolphins suggests touch is important in communication. Dolphins have a good sense of taste but lack the sense of smell. Dolphins live in world of sound. They use sounds to communicate and each animal has its own signature whistle which acts like a name. They can hear sounds as high as 150 kilohertz (bats hear up to 120) which are picked up through their jaw. Dolphins use sonar or echo-location to navigate and find their prey in dark and murky water. A series of "clicks" are made with the blow hole and emitted through their forehead. The echoes are heard through their jaw and enable the animal to form "sound images" of their surroundings. Dolphins may even be able to use super strong bursts of clicks to stun fish, making them easier to catch. The "popular" view of a human-like intelligence in dolphins is probably misplaced. 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.

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