Observations on sea water and sea bottom were conducted during 1989/92 period in the south coast of Sri Lanka, in order to understand the depth and substrata related distribution of spiny lobsters. Sampling of commercial Trammel net catches was also made simultaneously in order to understand the species composition in different locations' in the study area. Nearshore sand-stone reefs, coral reefs, submerged rocks and associated muddy bottom areas of the south coast of Sri Lanka provide a protective habitat for six species of spiny lobsters - Panulirus homarus, P. longipes, P. penicillatus, P. omatus, P. versicolor and P. polyphagus. All six species appear in any particular day’s catch of commercial fishermen and occasionally all six species occur in the catch of a single bottom set net. Entanglement of two or three different spiny lobster species in the nets layed in the same area is a frequent occurrence in the south coast. It seems possible that the dynamic events which result in the formation of zones associated with the bottom substratum provide sufficient selective forces in response to which all six species of spiny lobsters with different characters have evolved. Ecological separation of these species would be a result of a combined effect of several environmental parameters in their immediate vicinity and not as the result of a single controlling factor as discussed by some workers. This study also indicated that spiny lobster resources in the south coast of Sri Lanka were mostly confined to the 0 - 30 depth range and were most abundant on sand stone reef areas (5-15 m depth range) associated with submerged rocks.