Morphology of the buccal apparatus and related structures in four species of Carapidae

The aims of this study were (1) to compare the morphology of the buccal app aratus, the suspensorium and the opercle in four species of Carapidae (Cara pus acus, Encheliophis boraborensis, Encheliophis homei and Encheliophis gr acilis) and (2) to investigate the relationships between their cranial anat omy, their carnivorous diet, and their well known ability to enter holothur ians. The complex and strong dentition and the wide hyomandibular with thickening s that seem to suit the constraints of the adductor mandibulae muscles part ly inserted on the neurocranium are signs of a carnivorous diet. C. acus, E. boraborensis and E. homei have extremely strong buccal pieces a nd can protrude their upper jaws. However, in E. gracilis, the jaws are mor e slender, and the insertions of the Al along the entire length of the maxi llary associated with the lack of mobility between the maxillary and the pr emaxillary prevent buccal protrusion. These differences could be related to the diet: C. acus, E. boraborensis and E. homei can feed on fishes and cru staceans, whereas E. gracilis feeds only on holothurian tissue. The cephalic morphology of the four species is not incompatible with enteri ng the host. However, the neutralisation of the suboperculum spine by 'cart ilaginous' tissue could be considered to be a particular adaptation to this behaviour.