Starfish mating?

[jmaness084]

I have 4 large sand sifting stars in my 180gal reef. For about 2 weeks 2 of the stars have been locked together, one on top of the other. they both seem to be doing fine health wise still moving around in and on top of the sand. I was just wondering if they were mating?

 

[greenbean36191]

Well these stars will cannibalize each other, so that is one possibility, especially with so many of them in such a small tank.

However, what you're most likely seeing is pseudocopulation. The stars are broadcast spawners, but one crawls on top of the other so when the gametes are released from the bottom one they're guaranteed to pass within close proximity to the other star to greatly increase the odds of fertilization. In any event, they will not reproduce successfully in a reef tank.