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Shore Crab Claw Tufts

by WSG Crab Team | Jun 6, 2025 | Crab Team Newsletter Archive

Natural History Notes: HEOR Tufts

What are those blobby things on shore crab claws?

You may have occasionally noticed fleshy blobs on the inside of shore crab claws. They are most evident on males, which have larger claws than females. In fact these are tufts of setae [NEEDS NEW LINK], or fine hair-like structures, that emerge from the shell near the claw joint. The best way to get a good view of the structure is to get the claw in water and take a close look. The use of these is not well understood. They are most prominent in males, suggesting they might play a role in reproduction. These setae have chemosensory or smelling receptors at their base. Could these tufts help males locate females that are ready to molt and mate?

More info: Setae are important for all sorts of crab things. Read more about them in our previous newsletter article [NEEDS NEW LINK].

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