Synaptula lamperti

Synaptula lamperti is a sea cucumber from the family Synaptidae, part of the phylum Echinodermata, which also includes starfish and sea urchins. Like other echinoderms, it is radially symmetrical and uses a water vascular system powered by hydrostatic pressure to move, typically via tube feet. Sea cucumbers are generally leathery and cucumber-shaped, with a cluster of short tentacles at one end, and live on the seafloor.

Description

S. lamperti has an elongated, opaque body marked by several dark longitudinal stripes. It lacks tube feet on its body, but a few have been modified into a tuft of constantly moving, feathery feeding tentacles. Its skeleton consists of small calcareous plates embedded in the cuticle; these ossicles form tiny hooks that protrude through the skin, giving the animal a sticky texture. It moves quickly and efficiently by using the hooks at one end for adhesion while muscular contractions and shifts in hydrostatic pressure reposition the other end.

The genus Synaptula includes about thirty very similar species, and amateur observers often misidentify any of them as S. lamperti. Color patterns once used to distinguish these species—notably by Heding in 1928—are no longer considered reliable. The many synonymies of visually distinct species, especially with S. lamperti, mean that identification requires caution and verification by examining the dermal spicules.

S. lamperti occurs in the western Pacific, along the coasts of Indonesia, Papua New Guinea, Micronesia, and the Philippines. It is very common on coral reefs, both on exposed and inner slopes. It is a detritivore that feeds specifically on or around the sponge Ianthella basta.

Biology

It often remains firmly attached to the sponge’s surface for extended periods rather than moving across the substrate, indicating a sessile feeding strategy. It appears to need nutrients from this particular sponge, ingesting microscopic organic particles like diatoms as well as substances exuded from the sponge’s surface. It feeds only at night, and food passes through its digestive tract in under an hour.

Most individuals are either male or female, but hermaphrodites occur occasionally, and self-fertilization is possible. In the closely related Synaptula hydriformis, fertilized eggs are retained in the coelom, where juveniles develop in a protected environment. If S.