Life on the Leg of a Crab

Spider Crab feasts on the remains of a fish (Depth: 2229 m) Observation : 7282, 2012-06-15 00:07:11UTC, 1564. N47°55.9909′, W129°5.9243′ Credit: NEPTUNE Canada/CSSF

Neptune Canada, the world’s first regional-scale underwater ocean observatory network that plugs directly into the Internet, has an excellent Flickr photostream of deep-sea beasties.

A close up on the legs on the crab above reveals something amazing.

Close-up view of a crab feasting on fish (Depth: 2229 m) Observation : 7282, 2012-06-15 00:07:11UTC, dive 1564. N47°55.9909′ W129°5.9243′ Credit: NEPTUNE Canada/CSSF

Do you see it? Let me help.

What you see attached to the legs of the crab are skeleton or ghosts shrimps (there is actually a three, the third is just left of the upper red box). Ghost shrimps are not actually shrimps (in a group we call the Caridea) but rather in a group called the Caprellidae.  In fact they are not even in the same order (Decapoda vs. Amphipoda).  Caprellids are only found in the oceans and have a special pair of appendages for attaching to things like kelp, seagrass, small children swimming, or crab’s legs.  Although a few species filter feed particles out of the water.  Some are sit and wait predators patiently awaiting for another animal or really small child to get too close.  THEN BAM! A SMALL INVERTEBRATES MEETS ITS MAKER!

From Wikimedia CommonsCaprella mutica Schurin, 1935 Morphology (Male) Japanese skeleton shrimp.


Dr. M (1720 Posts)

Craig McClain is the Assistant Director of Science for the National Evolutionary Synthesis Center, created to facilitate research to address fundamental questions in evolutionary science. He has conducted deep-sea research for 11 years and published over 40 papers in the area. He has participated in dozens of expeditions taking him to the Antarctic and the most remote regions of the Pacific and Atlantic. Craig’s research focuses mainly on marine systems and particularly the biology of body size, biodiversity, and energy flow. He focuses often on deep-sea systems as a natural test of the consequences of energy limitation on biological systems. He is the author and chief editor of Deep-Sea News, a popular deep-sea themed blog, rated the number one ocean blog on the web and winner of numerous awards. Craig’s popular writing has been featured in Cosmos, Science Illustrated, American Scientist, Wired, Mental Floss, and the Open Lab: The Best Science Writing on the Web.

3 comments on “Life on the Leg of a Crab
  1. Wow!! Amazing pictures. Never thought of learning so much from crab legs. What is the age of this crab? The second picture looks broken or is it just men..Was the crab hurt in anyway?

  2. We get hundreds of these little guys on the ropes of our offshore acoustic stations. Sometimes they bite hard enough that you can actually feel them.

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