The feeding apparatus of two fiddler crab species, Uca vocans (Linnaeus, 1758) and U. tetragonon (Herbst, 1790)

抄録

We used a scanning electron microscope to study the minor claw and the first and second maxillipeds of Uca vocans and Uca tetragonon. Uca vocans had a slender, narrow minor claw with a wider gape, while U. tetragonon had a stout, broad claw with a narrower gape. In both species, sexual differences were slight in the lengths of the dactyl and propodus, and breadth of the minor claw. However, males of both species had deeper chelae than the females. Uca vocans had larger maxillipeds, appendages adapted to process large amounts of substratum, than U. tetragonon. Both species had spoonshaped setae on the inner side of the merus of the second maxillipeds, although U. vocans had more numerous setae, with larger spoon-shaped heads, than U. tetragonon. In both species, females scooped substratum more frequently using both chelipeds than the males, and produced a larger number of sand pellets. However, no sexual dimorphism was detected in the sizes and structures of the first and second maxillipeds.