The "decomposers and detrivores" of The Great Barrier Reef
Sea Snail
Sea Snails take up the majority of the snail population. They do have teeth but they are not like most teeth. They have radulas which are very hard ribbon like organs with tiny rows of teeth on them. When their teeth wear down new ones come in. They travel using a "foot" which is a muscular organ that is long and spreads underneath the body.
Fan Worm
Fan Worms feed by filtering out organic material from the water. They are segmented worms that are attached to rocks or sand by their base. Fan worms do not handle changes in temperature or salinity very well and therefore have been in decline in the Great Barrier Reef.
Sea Cucumber
Sea Cucumbers feed on small organic material. When threatened they discharge a sticky thread that ensnares their enemies.