Feeding behaviour of juveniles of the varunid crab Gaetice depressus (Decapoda: Brachyura: Varunidae)

Abstract

Adults of the varunid crab Gaetice depressus are known to engage in suspension feeding with the third maxillipeds, as well as feeding with the chelipeds. However, at what stage in life G. depressus becomes a suspension feeder has yet to be discovered. The present study aimed to elucidate the feeding behaviour of G. depressus juveniles using laboratory-reared first, third and fifth instars fed on non-suspended prey (i.e., krill and seaweed tissues) and suspended prey (i.e., diatoms and different-sized Artemia). This species fed on both non-suspended and suspended prey using their chelipeds and third maxillipeds from the onset of the juvenile stage. Experiments with Artemia of different sizes showed that the size of prey consumed by suspension feeding increased with instar, probably because of the growth or increased size of the maxillipeds. Similarly, cheliped manipulation for feeding on krill tissue improved with juvenile growth. Gaetice depressus juveniles switched between maxilliped and cheliped feeding or combined the two depending on prey size. This feeding behaviour may allow the species to consume diverse food sources.