LOBSTERS

Lobsters include large crustaceans from two groups, one with a pair of large claws and the other without. Clawed lobsters, yabbies and freshwater crayfish, live only in rivers and lakes in Australia but in the northern hemisphere there are marine representatives too. Marine lobsters, some of which are also called crayfish in Australia, do not have claws and are the ones figured here.
The carapace is calcareous and tough, reinforced to protect the internal organs of the head and thorax and the gills at the bases of the legs. The antennae are obvious, the compound eyes are on mobile stalks, there are six pairs of small limbs around the mouth, and five pairs of walking legs. The abdomen is strong and muscular, with a strong segmented exoskeleton on the back. It has the swimmerets underneath and ends in a tail fan.
During mating the male lobster transfers a packet of sperm to the female where it sticks and appears as a “tar spot” between the last legs. The eggs are laid through holes at the bases of the third pairs of legs and are attached to hairs on the swimmerets where the embryos develop until they hatch. As many as 600 000 eggs may be carried by a large adult female.
The eggs of Australian marine lobsters hatch as a larva called a phyllosoma. The translucent flat phyllosoma lives in the plankton for up to 22 months. In the Western Australian species of rock lobster the phyllosoma passes through nine instars lasting 9-11 months and is transported by currents well into the Indian Ocean before moulting to a stage looking much like a translucent miniature adult. This stage swims across the continental shelf to settle in shallow inshore reef areas.