Pacific bonito head. The caudal peduncle is slender, and the body entirely scaled. It has no teeth on the vomer. It has a small keel on either side of the median keel on the sides of the caudal peduncle, and six to eight finlets on the dorsal and ventral surfaces of the caudal peduncle. The maximum length is about 40 inches and weight 25 pounds. It is found anywhere from inshore to about 100 miles offshore from northern Vancouver Island to Mexico, though it is not normally found north of Point Conception. It usually travels in schools. Fish and squid are its
Operculum (gastropod) valves of a bivalve species, then for many years after that they were considered to be a form of paired or single operculum-like structures belonging to ammonites. More recently the aptychus or paired aptychi have been hypothesized to be a jaw apparatus of ammonites. Perhaps the most essential function of the operculum in gastropods is to allow snails to resist drying out, or desiccation. This is very important in intertidal marine snails during low tide, and this also enables operculate freshwater and land snails to survive periods of drought and dry weather. In those marine species where the operculum completely