Everyone knows that Australia has a unique terrestrial fauna. What is not so well known is that the south and south-east coastal areas of Australia support a unique range of marine animals. This is not so surprising when one considers that many fish and invertebrates need to live in shallower coastal waters and that southern Australia has been isolated from other land masses for millions of years. All sorts of creatures have evolved in our waters, to create a high level of endemism, or uniqueness. For example, out of the 600 species of fish found in southern Australian waters, some 85 per cent are found nowhere else. For other kinds of animal the level of uniqueness is even higher. This is a strong reason for supporting measures to preserve the biodiversity and richness of our marine heritage.

One fish family that is particularly Australian is that of the leatherjackets. Of the 97 species worldwide, 60 are found in Australia and 22 are found only in southern Australian waters. Most leatherjackets are medium-sized fish. They are rather oddly shaped, with a large head, sloping down to a small mouth. They have a sharp spine on the top of their heads and sometimes spines on their sides just in front of the tail.

The cutest member of this family is the pygmy leatherjacket , a very small, almost circular fish, which spends its days camouflaged among seaweed. When approached it fans its tiny fins furiously to keep it moving away from the observer. At night it can sometimes be found sleeping with its tail curled around a seaweed stalk.

The six-spined leatherjacket is one of the larger members of the family. It gets its name from the prominent spines just in front of the tail. These are believed to be used for slashing the sides of other leatherjackets with which they compete during the mating season.

The fan-bellied leatherjacket is an untidy-looking fish, with a large flap hanging down under its belly. It is a fish of tropical waters, but seems to be becoming more common in our waters, perhaps as a sign of ocean warming.

Many species of leatherjackets prefer shallow reef habitats, so that anyone who goes snorkelling is likely to find some representatives of the family. Some species are caught by recreational fishers and spearfishers. The most important commercial species is the chinaman leatherjacket but, because of overfishing, most now come from South Australia.