A yabby is an Australian freshwater crayfish that live in rivers, streams and dams. In Victoria and New South Wales they are called yabbies, in Western Australia they are called marrons and in Queensland they are known as redclaws.

Yabbies belong to the animal group crustaceans. They are invertebrate arthropods. Arthropods have jointed legs.  Invertebrates are animals without backbones. Instead, they have a hard outer shell that is like armour protecting the inside of the body. The outer shell does not grow, so the animal regularly moults, or sheds, its outer skeleton revealing a new, larger one, underneath.  Yabbies moult many times in their lifetime, but more when they are younger and still growing.  

Body

Yabby bodies have three section: head, thorax and abdomen. Two pairs of antennae are on the head. Attached to the thorax there are big pincers (the first pair of legs) and four pairs of small legs called swimmerets. The pincers take food to the mouth. The abdomen is the edible part, with a tail at the end.  

Colours range from brown, green or even pale blue, depending on the water they are living in, muddy or clear. After moulting, the new shell colour also matches the water.

They are detrivores, which means they are scavengers that eat anything, such as dead things they find, plants, algae,  small fish and worms.

Life cycle

Yabbies hatch from eggs. The female lays between 100 and 1,000 eggs and keeps them protected with her tail flap. When they hatch after 20-40 days, the young are released into the water.

Yabbies are pretty hardy, and can survive in very cold or very hot conditions. However, if water temperature drops to 16ºC or less, they go into a sort of hibernation. They do not need to be in the water all the time, and actually travel between waterholes and streams.

Read more about yabbies

http://australianmuseum.net.au/image/yabby-illustration