Changes of the setae on the mouthparts of the red king crab Paralithodes camtschaticus (Tilesius, 1815) (Decapoda: Lithodidae) during ontogeny

Setae on the mouthparts of juvenile and adult red king crabs, Paralithodes camtschaticus (Tilesius, 1815), were studied. A total of seven types of setae have been differentiated; their distribution over the mouthparts was determined. It was established that setules and denticles on the surface of setae show a tendency to shorten and/or disappear as the body grows; the length of the setae decreases relative to the size of the individual; the number of setae of most types increases considerably, forming dense groups of setae. These changes are apparently related to the fact that the effectiveness of the functions that are performed by solitary setae decreases with the growth in the size of an individual; these functions are subsequently assumed by groups of setae.