The world's smallest species of crayfish has been discovered in the coastal lakes and swamps of southeast Australia.

The tiny, dark blue crustacean resembles a lobster or a crawdad, yet measures only half an inch long. It has been named Gramastacus lacus.

It is also one of the smallest cannibals on Earth and has long claws called chelae to defend itself from other hungry crayfish or predators.

The tiny new crayfish species, Gramastacus lacus, discovered in New South Wales Robert McCormack

It was found in the lowland transient habitats of Wamberal Lagoon and Wallis Lake, where it is protected by thick grasses and reeds from predators such as eels, birds, fish, lizards and turtles.

Despite its small size, the crayfish can burrow up to 3ft. This helps the animals survive long dry spells, when Australia's coastal swamps drain.

The species was discovered in one of Australia's most urbanised regions. It has suffered a significant destruction of its natural habitat, as transient areas are drained and built up.

With the discovery of Gramastacus lacus, it is hoped that future habitat loss may be reduced.

Falling water tables and rising sea levels are also a danger, although national parks and reserves along the coast provide a safe refuge.

Only one other known species of Gramastacus crayfish, which originated around 500 miles away in the Grampians region of Victoria, has been found. Gramastacus insolitus is classified as "near threatened" by the International Union for Conservation of Nature Red List of Threatened Species.