|Cestum veneris Lesueur, 1813 – Venus’ Girdle
Phylum Ctenophora / Order Cestida / Family Cestidae
Consider yourself fortunate if you encounter this impressive comb jelly in California waters. A cosmopolitan inhabitant of tropical and sub-tropical seas, the Venus’ girdle is an infrequent visitor in surface waters as far north as Monterey Bay. With its ribbon-like shape and length up to 1.5 meters (although usually not exceeding 80 cm) , it’s hard to mistake with any other comb jelly, with the exception of its far smaller relative, Velamen parallelum. Cestum is generally transparent, but may have a violet color and yellow pigment on the tentacles, canals and near the tips. Gonads form a continuous line along the length of the body, unlike those of Velamen, which have a broken appearance. Tentacles are attached to a groove that runs along the oral edge, which is positioned forward as the comb jelly swims. The tentacles trail back over the body during normal swimming motion. Copepods and other small zooplankton prey are captured by the tentacles and transported to the mouth which lies at the center of the leading edge. The comb rows are on the aboral edge of the body, opposite the tentacles and mouth. When disturbed, Cestum has an escape response that consists of rapid undulation in a direction perpendicular to the direction of normal swimming. It can appear worm-like when using this response. The tissue is very delicate and easily broken apart by disturbance from a diver or during an attempt at collection.
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