Operculum (fish) required, such as ventilation.. Operculum (fish) The operculum is a series of bones found in bony fish that serves as a facial support structure and a protective covering for the gills; it is also used for respiration and feeding. The opercular series contains four bone segments known as the preoperculum, suboperculum, interoperculum and operculum. The preoperculum is a crescent-shaped structure that has a series of ridges directed posterodorsally to the organisms canal pores. The preoperculum can be located through an exposed condyle that is present immediately under its ventral margin; it also borders the operculum, suboperculum, and interoperculum posteriorly. The
Caudal luring often in juvenile snakes and is most prevalent in vipers and pitvipers, but it also occurs in boas, pythons, tropidophiids, colubrids, and elapids of the genus Acanthophis. Caudal luring has been used as an experimental paradigm to investigate stimulus control and visual perception in viperid snakes. It has been suggested that caudal luring was involved in the evolution of the rattlesnake rattle. Attempts have been made to test this hypothesis, however, the evidence is contentious. There have been dubious reports of caudal luring and concomitant speculations. Prey luring in general is confounded by false interpretation. The difficulty is that there