When one of my hermit crabs decided to upgrade his shell, I gave his old home a prime position in the tank front and centre next to the glass. Why did I feel the need to feature an empty shell? Well, this particular shell is home to an abundance of neat hitchhikers.
Aside from the purple coralline algae there are the the bumpy pink blobs, these are a colonial foraminifera called Homotrema rubrum.
These forams feed on tiny particulate matter, bacteria etc that they catch using fine filamentous protoplasmic strands that poke out of the pink shell. Apparently the pink colouration is due to an iron salt that is incorporated into the shell. Pretty cool huh!
Then there are the teeny tiny barnacles. There are at least a dozen scattered over the surface of the shell. I love watching them extend their feather like cirri in and out sifting for food. I fully expected them to starve quite quickly in my tank but they must be finding enough food as they are still doing their thing.
Additionally in the photo above you can just about see a pair of dark/transluscent coloured things (no idea what that is) top left and another pair of whitish siphons just to the right of them, a tunicate or sponge maybe? There are also some small chaetopterid worms and vermetid snails too (they get everywhere). Last but not least a baby sun coral has decided to join the party too.
So much life on one small snail shell and that's not even counting the amphipods and mini brittlestars that are taking shelter inside and underneath it. Too cool!
On the 31st December 2016 I introduced Zoanthus sp. #1 to the tank. On the rock along with the zoas came a mystery disc thing that I identified as a foraminifera called Marginopora vertebralis (see here). For a couple of months nothing changed and then suddenly it vanished. I assumed that it had died and had fallen off the rock or had been knocked off by a snail or hermit crab. The following day I discovered it just behind the zoa rock. A few days later however it was in a different spot, OK, so the hermits or snails must have been moving it during their never ending rock cleaning duties. But then a few days after that it was in yet another spot and no way could it have been placed there by a crab or snail unless I have very, very clever snails/hermits. During the next two days I paid extra attention to the foram and lo and behold it was moving around the rock, all be it very slowly, of its own accord. Who knew it could do that?? I certainly didn't!
I have since discovered that foraminifera can move about with slender pseudopodia, or extensions of cytoplasm, the living matter of the cell, which stream through an opening in the test known as the aperture; in porous tests, the pseudopodia also emerge through the pores.
Please see the link below for more details:
This thing is seriously cool!
One of the things I love most about reef tanks is discovering and identifying new creatures. Yes, some of it can be problematic (as per yesterday's post) but some of it can be hands down cool too (well certainly to me anyway).
Last weekend I noticed an unusual disc thing attached to the zoanthid rock (yes again the zoa rock, it's just full of surprises, lol!). I was immediately curious to find out what it was. It's a sessile flat disc measuring just 2mm across. To the naked eye it doesn't look like much but on closer inspection (with a macro lens) it has a beautiful radial pattern with a distinct middle section. My initial thought was a type of foraminiferen which belongs to a group of single-celled organisms (protists) with shells. I decided to request the help of an expert at foraminifera.eu to help with identification. He confirmed that it is indeed a sessile benthic foram called Marginopora vertebralis. Pretty cool huh!
Hi, my name is Lisa and I live in Derby, UK. I am a self-confessed reefaholic!