Ctenophora: Class Tentaculata
Members of this class typically have two feathery tentacles that can be retracted into specialized sheaths. In some, there are smaller, secondary tentacles, and the primary tentacles are reduced. This class includes the small, oval sea gooseberries (genus Pleurobrachia ), common on both Atlantic and Pacific coasts. The more flattened Mnemiopsis, about 4 in. long (10 cm), is common on the upper Atlantic coast. Known as a sea walnut, it has a large mouth and feeds mainly on larval mollusks and copepods. This species is brilliantly luminescent. The similar, but larger, genus Leucothea is abundant on the Pacific coast. Venus's girdle (genus Cestum ) is a flattened, ribbonlike form reaching over 1 yd (91 cm) in length, and found in tropical waters.
The Columbia Electronic Encyclopedia, 6th ed. Copyright © 2012, Columbia University Press. All rights reserved.
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