If you don't mind, could you take a look at these photos (attached) and tell me what you think may have caused the condition in these crabs? They show some curious black lesions on Metacarcinus magister (formerly Cancer magister) we caught during a biological survey about 10 nmi off the mouth of the Columbia River last summer. They were caught in a dredged material disposal site in a few hundred feet of water over silty-sand substrate. Could they be from chitinoclastic bacterial infection or something else?
I appreciate any insight that can be offered. Thanks!
probably "black spot" disease caused chitinolytic, gram-negative bacteria you should be able turn up references fairly easily.
probably "black spot" disease caused chitinolytic, gram-negative bacteria you should be able turn up references fairly easily.
hello,
any lesion or crack in cuticle led to melanin formation at the area of injury. this is so common in crabs when they fight and bite each other. any injury of this type resulted in black cuticle. even if the seta of amphipods are broken the remaining part shows a black dot. I can sea in the second crab some crack on the chela with black marking.
As already mentioned, it's due to chitinolytic bacteria on a damaged or abraded part of the exoskeleton. In minor cases they can get rid of it in the following molt.
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