Very strange double snail

Hi, has anyone heard of a small snail/limpet living on the underside of another snail like a parasite. I've never seen this before, but my girlfriend noticed it on one of our starshells.
















It doesn't seem to be doing any harm to the starshell and looks more like a symbiosis, sort of hitch hiking. Both snails are feeding on the thin layer of algae on the glass in my lagoon tank.

Has anyone seen one of these before?

 

weird/cool!

 

i have one of those on one of my astrea snails. so far hes still alive.

 

Do you have any idea what the smaller snail is called?

 

i had something similar on my mexican turbo got anoyed at it after a while and pulled him off my turbo snail only to find a hole in my turbo snail's shell (did'nt go all the way though) after that that second snail is never allowed in that tank i think he was trying to eat my turbo (jose)

 

I have also had an astraea snail with two smaller snails fixed to it's shell. Almost looked to be astraea snails as well (obviously much smaller ones). They did seem to be attached pretty well however, as my attempt to remove them proved futile. (shells possibly fused together over a bit of time?)

 

The limpet-like snail attached to your astraea is probably a Hipponix species. They are considered semi-parasitic, although they don't feed on the snail at all. They may make holes in the shell of the host species, however, which probably isn't great for the host snail. In "Intertidal Invertebrates of California," by Morris, Abbott, & Haderlie, the feeding habits of one species, Hipponix cranioides, is described, which is presumably similar to others in the genus:

"The animals feed by actively extending the long, mobile proboscis and grasping fragments of coralline algae and detritus. The variety of material found in the gut shows that the animals take whatever is washed within reach and are not fussy feeders. One might expect such sedentary animals to have evolved the ability to filter feed on plankton, but this has not occurred."

Hope that helps. Cheers,




Don

 

The fifth pic down is wicked. It look likes something from predator!arty-smi

 

K+ I just googled Hipponix species found a website with this spp and a few other parasitic limpets, I think it might be either Hipponix australis or Malluvium devotum.

Hipponix australis

Malluvium devotus

Phil