Invertebrates: Sea Slugs & Sea Cucumbers

Seeing as how I only have one photo of a sea cucumber, I figured I’d combine the sea slug and sea cucumber pages.  Sea slugs are like shell-less or nearly shell-less snails while sea cucumbers are more related to starfish.  More specifically, nudibranchs are the “naked-gilled” sea slugs.
Elysia sp. – Reef Safe
These are from the phylum Mollusc, class Gastropod, order Sarcoglossa, family Elysiidae. This tiny yellow sea slug is occassionally found in saltwater aquariums, usually as a hitchhiker.  One of my favorite LFS had these everywhere in their reef tanks, and they were usually munching on algae.  Overall, I’m against purchasing nudibranchs as most of them are very picky eaters – they will only feed on one species of whatever (sponges, algae, etc.)  However, if you happen to find one of these in your aquarium, enjoy it!
Montipora-Eating Nudibranch – Not Reef Safe
Montipora-Eating Nudibranchs are from the phylum Mollusc, class Gastropod, order Nudibranchia, and sub-order Aeolidoidea. Identification down to the species level has not yet been accomplished to my knowledge.They are white in color and range in size from 1-3mm in length.The body is covered in cerata, which may store the nematocysts (stinging cells) of the coral to help protect them from predators.  As the name implies, their sole source of food is the Montipora coral.  More info.
Sea Hare (Aplysia sp) – Reef Safe
Sea Hares are in the phyllum Mollusca, class Gastropoda, order Opisthobranchia, family Aplysiidae, and are named for their rabbit-like appearance and mannerisms.  Ear-like sensory-organ extensions (called rhinophores) on their heads are the main reason for their namesake.  They feed on various filamentous algae and macroalgaes, although their particular diets can vary by species and age.  They are simultaneous hermaphrodites (both male and female reproductive organs) and have been bred in captivity for decades.
Blue-Spotted Sea Hare (Bursatella leachii) – Reef Safe
This sea hare is quite attractive with a dark brown to black body with bright blue spots.
Green & Pink Sea Cucumber (Pentacta anceps) – Reef Safe with Caution
This sea cucumber is from the phylum Echinodermata, family Holothuriidae. It’s a filter-feeder, so it should only be placed in large, mature aquariums with a good refugium or else it will slowly starve. It usually chooses one spot and will stay there until it becomes unhappy. If it moves constantly, it is not happy and should probably be removed from the aquarium. Although these are not as poisonous as sea apples, they can be quite detrimental to an aquarium upon death.

Leave a Reply