Cerithium crawling out of a bucket. The common name for Cerithium is "horn shell." This species was collected on mud in a mangrove swamp. Note the long snout, and the tentacles, which are short, stubby, and have eyes at their tips.

Note the anterior apertural canal; also the operculum attached to the back of the posterior foot.


bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.


animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature