Ophiuroids Flagrante Delicto and Notes on the Spawning Behavior of Other Echinoderms in their Natural Habitat

Spawning activities of an ophiuroid, Ophiarthrum pictum, a comatulid crinoid, Capillaster multiradiatus, and a holothuroid, Bohadschia marmorata, were observed on a shallow patch reef at 3–12 m depth in the Palau Islands, Western Caroline Group, Pacific Ocean. Spawnings of all three echinoderm groups shared the following characteristics: with one exception spawnings occurred at night, shortly after sunset; the echinoderms raised their bodies above the substratum by means of a distinctive spawning posture or elevated perch; spawnings were restricted to certain dates, none coincident with new or old lunar phases. These adaptations may minimize predation on adults and wastage of gametes, and maximize dispersal of zygotes. This is the first report of ophiuroid and holothuroid spawning in nature and the second of crinoid spawning in nature. Spawning activities of the ophiuroid and holothuroid confirm data derived from laboratory spawnings.