Abstract:
Two-hundred forty two Callinectes rathbunae crabs parasitized with Loxothylacus
texanus were caught; of them, 233 showed some type of lesion related to
shell disease. The organisms with virgin externa showed grooming activity and
the organisms with mature externa did not show that behavior; they only groomed
merely the externa, like egg-bearing females do. Sediment accumulation was observed
on the shells of these organisms. Another aspect observed was that the organisms
with virgin and immature externa had the ability to swim and the crabs with
mature externa lost swimming mobility; some of these organisms lost even mobility
of their walking legs. The most common lesions were ruptures or cuts (104),
followed by brown spots and ulcerations (95), brown spots (20) and ulcerations
(7). This is the first report where serious injuries in the abdomen of crustaceans
affected with shell disease are documented, showing even loss of exoskeleton
and cuts, since this type of injuries were not found in the consulted literature.
Summarizing, shell disease is characterized by: (1) the appearance of brown
spots, (2) the appearance of brown/black spots with brown/black halos, (3) the
appearance of ulcerations with brown/black halos, (4) perforations and (5) loss
of large amounts of exoskeleton. We can conclude that this is the first record
on shell disease in C. rathbunae parasitized by L. texanus and
the presence of L. texanus on C. rathbunae is probably a stress
cause that facilities the establishment of bacteria on parasitized dark crabs.
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