Postcard from the Reef – Keferstien’s Sea Cucumber

As I have discussed before, there are some weird critters on the reef. Some of the more alien appearing creatures are the sea cucumbers of the family Synaptidae, the thin-walled sea cucumbers. These look like large worms, moving across the reef by expanding and contracting their bodies. At the front end are a set of feeding tentacles, sweeping out in slow motion to move food to the mouth at the center. The body is flaccid, supported and given shape through an internal hydraulic system.

The small brown Keferstein’s sea cucumber is surprising sticky, with small hook-like spicules on its outer skin. It sticks readily to dive gear, twice now I have seen these critters stuck to a diver without the diver knowing. Carefully peeling them off they make a nice photographic subject before allowing these normally nocturnal critters to escape back into a crevice in the coral.

Keferstein's Sea Cucumber
Keferstein's Sea Cucumber (Polyplectana kefersteini) at 30ft, Puako

Postcard from the Reef – Hawaiian Spiky Sea Cucumber

These sea cucumbers are well known to divers and can be found in the local guide books. There is no scientific name, the species has never been properly described. An odd state of affairs for a relatively common critter. As for the name? I could come up with a few other common names that seem to describe the appearance. However, naming a species after a pile of doo-doo is not generally acceptable.

Hawaiian Spiky Sea Cucumber
Hawaiian Spiky Sea Cucumber (Stichopus sp.) at 100ft depth off O’oma, the species is well known but undescribed in the literature