Reef Ecology Guide Phuket Thailand - Crustaceans

The crustaceans are one of the truly dominant groups living on coral reefs. However, due to the tiny size and cryptic habits of many species, it is easy to under-estimate their impact on the reef's ecology.

The group is incredibly diverse with regards to size, shapes, colors and life style. Not only does it include well known representatives such as lobsters, shrimps and crabs, but also a wealth of microscopic organisms that form a large portion of the zooplankton.

Crustaceans are typified by the presence of a calcium carbonate-based external skeleton. Because of continuous growth throughout the life cycle, the animal periodically outgrows its armor coating. Therefore the shell is shed and replaced at regular intervals. When the shell is shed and the new coat is still relatively soft the animal is vulnerable to predators and therefore seeks shelter in a burrow or other hiding place.

Generally the best time to observe crustaceans is at night when many species emerge from their retreats to feed. The most conspicuous crustaceans during daylight hours are those that clean parasites from fishes. The so called cleaner shrimps are frequently bright colored and occupy permanent stations that are regularly visited by a variety of fishes.