Predation, physical disturbance, and sublethal arm damage in ophiuroids: a Jurassic-Recent comparison

The proportion of ophiuroids with sublethal arm damage (regenerating arms) was censused over 4 yr (1987 to 1990) in a lagoonal population of Ophioderma brevispinum (Say) (Ophiodermatidae) at Belize, and over 3 yr (1988 to 1990) in back-reef populations of 0. appressum (Say) at Belize and Jamaica. The Jamaican population was sampled in sheltered and wave-exposed areas. Over the study period, the frequency of injuries within populations did not differ significantly, nor did the 2 0 . appressum populations show consistent differences. Arm injuries were more common in the 3 living populations (30 to 74 O/ O injured) than in a Lower Jurassic population composed of 2 ophiodermatid species (0 O/ O injured) from a similar warm-water habitat. The incidence of sublethal disk damage was negligible in all cases. Hurricane-generated rubble movement did not cause any detectable damage to either the protected or exposed Jamaican 0. appressum subpopulations. Predation is the primary source of arm injuries in living Ophjoderma spp. This study supports the hypothesis that predation on ophiuroids increased when durophagous teleostean fishes and decapod crustaceans diversified in the late Mesozoic.