Morphological and sensory specializations of five New Zealand flatfish species, in relation to feeding behaviour

The morphology of the feeding apparatus and sensory systems of flatfish species Rhombosolea plebeia (Richardson, 1843), Rhombosolea leporina Günther, 1862, Peltorhamphus novaezeelandiae Günther, 1862, Pelotretis flavilatus Waite, 1911 (f. Pleuronectidae) and Arnoglossus scapha (Forster, in Bloch & Schneider, 1801) (f. Bothidae) are described. The four pleuronectid species have asymmetric jaws and non-toothed gill rakers typical of benthic-feeding flatfish, while the bothid has symmetric jaws and toothed gill rakers typical of midwater-feeding flatfish. R. plebeia, R. leporina and P. novaezeelandiae have extensive external taste bud systems which facilitate non-visual prey location. External tastebuds are lacking in P. flavilatus and A. scapha ; however, these two species have relatively large, prominent eyes which facilitate visual prey location. The lateral line is well-developed in all five species, but R. plebeia, R. leporina and particularly P. novaezeelandiae have additional free neuromasts on their blind sides, which probably assist in prey location.
The feeding habits of these flatfish species closely reflect their morphological and sensory specializations. A detailed feeding study in Wellington Harbour, New Zealand showed that R. plebeia, R. leporina and P. novaezeelandiae have closely overlapping diets consisting of largely sedentary or inactive invertebrates living in the bottom sediments. In contrast, P. flavilatus and A. scapha have specialized diets of one or two species only. While the latter two species differ in that P. flavilatus is a benthic feeder and A. scapha is pelagic feeder, both are visual feeders and therefore more specialist than the other three species.