Monday, May 23, 2011

Spider Crabs

Over the weekend we went to Home Beach to collect Cuttlebone for the chooks and garden, which John grinds up. We immediately noticed lots of dead crabs.

Spider Crabs Leptomithrax gaimardii were in abundance and we wondered why. So John put his research hat on and this is what he found out!

So why did they come to be washed up on the beach? Most of the crabs were just the cast off exoskeleton (exuvia) of the animals.

They would have been especially vulnerable to being washed ashore in windy weather as their muscles are reduced during moulting to allow their limbs to be extracted and spider crabs are very weak and spindly, even in peak health.

Reports have been made apparently every few years in the past 20 years of crabs being washed up on beaches. It seems to be a regular natural event.

If you would like further reading -

Hale, H.M. 1927-29 The Crustaceans of South Australia. Adelaide: Government Printing South Australia.

1 comment:

  1. Hi John and Bev,
    Yeah we also saw heaps of Spider crab shells in Shepard's Bay and wondered what was going on. Thought there must have heaps so we put a pot down, which something ripped up! John and Lyn are up north doing a land trip near Lawn, they pass on their best wishes.
    Jack and Jude