Abstract
The behaviour of the spiny lobster, Panulirus cygnus, of Western Australia was studied in the laboratory and field. A brief description of behavioural units is provided. A den residency survey showed only 3% of the lobsters sheltered singly, and the number of lobsters in a single den ranged from 1 to more than 100. Lobsters left dens in the evening and returned in the morning, following specific pathways along the reef face, implying knowledge of the local topography. The lobsters returned to the same area of the reef but not necessarily the same den after foraging. The occupancy of any particular den remained fairly constant over a period of time but changed markedly after a storm. The reactions of lobsters to a predator (Octopus tetricus) released at the mouth of a den were high alert postures, antennae pointing and waving, and slow retreat from the den. In a large laboratory pool, stridulation and tail flip were frequent when an octopus was out of its lair and moving around.