Ceriantharia

an order of marine invertebrates of the class Anthozoa. The Ceriantharia are solitary polyps that burrow into silt, from which only the brightly colored upper end, with a mouth and numerous highly extensible tentacles, is visible. The body, which has no skeleton, is cylindrical and enclosed in a protective casing of solidified mucus. It ranges in length from 2 to 70 cm. The partitions of the gastral cavity develop in the only zone of growth near one of the narrow sides of the gullet, which is laterally flattened; they are arranged in pairs—a sign of bilateral structure.

The Ceriantharia feed on various small animals, which they capture with their tentacles. Approximately 50 species are known; they are found mainly in tropical seas.