Copepods of the genus Asterocheres (Copepoda : Siphonostomatoida) feeding on sponges: behavioral and ecological traits

Four copepod species of the genus Asterocheres (A. echinicola, A. latus, A. suberitis and A. complexus) are recorded for the first time as associated with Mediterranean sponges of the classes Calcarea and Demospongiae (orders Dictyoceratida, Dendroceratida, and Poecilosclerida). Individuals of A. su beritis are described for the first time as inhabiting sponges other than S uberites domuncula. The copepods seemed to use their trunk to suck the mate rial (cuticles or excreted cells) produced at the sponge periphery (ectosom e), which indicates that their feeding habits are similar to those observed in species of the same genus that feed on exfoliated tissues of echinoderm s. In the laboratory, copepods fed on young sponges (rhagons) of the specie s Crambe crambe, Cacospongia mollior, and Dysidea avara without reducing th e rhagon biomass. In contrast, rhagons of the species Haliclona sp., Hymede smia spp., and Phorbas tenacior were consumed and their biomass reduced. Th is may be because the latter group does not produce external proteinaceous material. Copepod offspring were continuously released (similar to6 nauplii every 48 h) and the larval stages were capable of limited swimming. We fou nd significantly more copepods over the surface of the sponges than inside them. Copepod abundance was positively correlated with the sponge surface a rea while not with the sponge biomass. These results indicate that the cope pods live preferentially over the sponge surface and that their abundance i s surface-area dependent. The behavioral traits described here indicate tha t the interactions between asterocherid species and sponges are worthy of f uture study.