Native marine aquaria are pretty scarce. Little information exists on how to be successful in maintaining healthy coldwater marine systems in domestic aquaria.

Hopefully this record of my failures, triumphs and ideas will assist others interested in keeping some of our fascinating, beautiful and often little known sea denizens in aquariums.

Saturday, 4 September 2010

Spider Crabs

I recently caught 2 of these small unidentified spider crabs hiding in thick corraline algae on the side of a rockpool. Possibly from the subfamily Pisinae, formal identification would involve stripping the creature of its camauflage, which seems unneccesarily stressful. I'll wait for it to moult. The carapace is about 25 - 30mm at present, the nostrum appears to be quite long and pointed. Pincers are small and delicate and the legs are quite short.

The camauflage is exceptionally effective. The crab carefully selects small, often living pieces of alkgae, passing them to its mouth where it appears to mumble something upon it which allows it to then stick it to a part of its body. All parts are covered in a garden of living algae except for the pincers and underbelly. The crab seems to spend a considerable amount of time in maintaining this garden. Its practically invisible!

probing in the sand with its pincers - presumably for worms?

investigating a newly introduced mussel

hanging upside down on a 'woody' algal branch feeding on algae. a few minutes later it found a tiny topshell which it delicately extracted form its shell and ate.

apart from the pincers the creature is impossible to differentiate from its surroundings

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