ID on this starfish

[Klewtz]

Hello everyone,

I got this starfish from my LFS and I am unable to find this starfish anywhere online to find information. They said it was a “common star” aka “Caribbean star” but when I look this up nothing comes up that looks similar. The underneath is very bright orange! Thanks in advance!

 

[Doompastew]

Brown Mesh Sea Star

 

[vetteguy53081]

Very difficult to keep in captivity specimen which gets large

 

[ISpeakForTheSeas]

This is an Echinaster (Othilia) species; either graminicola, sentus, or spinulosus.

There are some differences between each species, but they have a lot of similarities as well:

For clarification here, Echinaster (Othilia) spinulosus (and closely related species like Echinaster (Othilia) echinophorus) in the wild are thought to primarily feeds on sponges, tunicates, biofilms, detritus, and dissolved organic matter (DOM). They can also filter nutrients directly from seawater through their skin. Anyway, they are known as both opportunistic predators and scavengers. In captivity, many sea stars - including Echinaster (Othilia) spinulosus - are known to eat unnatural diets, consuming things like shellfish (including shrimp), bivalves (clams, mussels, oysters, etc.), small starfish (like Aquilonastra spp. - known in the hobby as Asterina stars, though those are species of a different genus in the Asterinidae family), and even sand dollars.

Echinaster (Othilia) spinulosus is known to be a long-lasting species for aquariums, which indicates to me that there is a good chance they're dietary needs are more readily met by things like bivalves, unlike Linckia spp. and similar, which tend to die off within a year even when regularly offered things like clams to eat.

With regards to Echinaster sentus specifically, from what I’ve been able to find, they eat bivalves (clams, mussels, scallops, etc.), sponges (they accept some species that have chemical defenses against fish, but it seems they prefer those with little to no chemical defenses period), possibly some anemones, and possibly other sessile (immobile) inverts too (so it may at some point go for corals, or it might not - there's not much information available on the diet of this species). You could probably supplement feed it using things like clams and sponges (carolina.com carries some relatively cheap sponge packages), but there's no guarantee it will survive long term. If you decide to try it, let us know how it works out after about 18 months - again, I'd be genuinely curious.