Sand Dwellers of Wakatobi

Published July 9, 2018 in MARINE LIFE
Starfish are iconic creatures with the most rudimentary central nervous systems, and eyespots that can only detect the difference between light and dark.

Starfish are iconic creatures with the most rudimentary central nervous systems, and eyespots that can only detect the difference between light and dark. Photo by Glen Cowans

Yet despite their seeming simplicity, starfish are well-adapted to their environment, as they have been around for almost 500 million years, and can live for up to 30 years. Starfish are members of a group known as echinoderms. They move about on hundreds of tentacle-like structures called tube feet, which are also used to capture and hold food. Most move at a pace that is almost too slow to detect, but some species can zip along at speeds of up to an inch a second.

Fire urchins like this one prefer an open bottom such as sand and grass beds and tend to move in groups.

Fire urchins like this one prefer an open bottom such as sand and grass beds and tend to move in groups. Photo by Erik Schlogl

Another type of echinoderm that is more common on rocky bottoms, but will sometimes venture out onto the sand, are the urchins. Beneath their bristling array of spines, urchins share many physical characteristics of the starfish. They are covered in a series of hard calcium plates and move about on five rows of paired tube feet. At Wakatobi, it’s not that common to find urchins on the sand, but when they do show up, there’s usually more than one.

Sea cucumbers play a vital role in the health of the ecosystem, as they are the janitors of the sand. Less glamorous than the starfish and urchins are the sea cucumbers. These often-overlooked echinoderms move about by flexing their bodies and inching along the seafloor, sucking in detritus, which is digested and ejected as clean sand. Sea cucumbers actually play a vital role in the health of the ecosystem, as they are the janitors of the sand.

Starfish often have hitchhikers aboard such as this blue starfish shrimp, which takes on the same color as its host.

Starfish often have hitchhikers aboard such as this blue starfish shrimp, which takes on the same color as its host. Photo by Walt Stearns

For divers and underwater photographers, the most interesting aspects of starfish, urchins and sea cucumbers aren’t the animals themselves, but the tiny hitchhikers that can often be found riding along. These passengers include commensal crabs, small shrimp, and even the occasional nudibranch. To escape notice, a number of these small creatures take on the coloration of their host. For example, in Wakatobi waters, there are a particular species of blue shrimp that can be found on blue starfish. The most diverse menageries of hitchhikers are usually found on urchins, seeking shelter among the spines/

Though not as glamorous as some of the reef dwellers you will find at Wakatobi, the creatures of the sand can be quite interesting to observe and photograph. Devoting some bottom time to discovering this world away from the corals can add yet another dimension to the diving and snorkeling experience.

Thinking about a trip to see the sand dwellers? Start by contacting our office at office@wakatobi.com, or complete a quick trip inquiry at wakatobi.com. A guest experience consultant will be in touch with you to answer any questions and provide information about your dream dive vacation.

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