Emerick Fish Tank

[Emerick Elementary]

We are starting to get worried.  We can't seem to find our seastar.  We also have lost our yellow fox face.  Is there any change that the serpent brittle star could be behind all of this?

 

Observations made by students:

The anemones and gorgonian seem to change when the light is off in the tank. 

The seastar one day was on top of a snail.  Was he eating it?

The sea urchin has been moving more and more.

[davelin315]

Common tropical anemones are photosynthetic and will close up at night to a certain extent whereas gorgonians which are typically not photosynthetic will open up their polyps at night to feed.

 

Depending on the type of seastar, it could have been eating the snail or it could simply have been moving.  The way to tell is by looking to see whether it has extruded its stomach to digest the snail or whether it's still inside its body.

 

In terms of the seastar, they are very sensitive to any changes in salinity, temperature, pH, and water quality.  If you had a swing at any point in time, it's possible that it simply dissolved.  Look for bb sized or smaller granules on the bottom of the tank - this could be a sign that the starfish dissolved and left behind parts of its body.  Oftentimes when they die, you will find no remains because their bodies literally go to pieces or dissolve outright.  The stressor that causes this could also have been very remote in time to the point where you would never have known it went through any issues at all.

 

In terms of the fox face, if it's been missing for a while, chances are it's dead and has been digested.  In terms of the serpent star being the culprit, if it's a green serpent star, they can be voracious predators and eat anything they can catch, but most others will not do this.  When you say serpent brittle star, there are actually serpent stars and brittle stars, with the brittle stars being spinier and the serpent stars having no spines typically (at least with what we see in the trade).  The green serpent stars have spines on the lateral edges of the arms but none on the central disc or the surface of the arms.