Meeting Abstract

P1.57  Sunday, Jan. 4  Why don’t kissing gourami capture prey from the water column? GIBB, A; MELVILLE, B*; WALSH, K; FERRY-GRAHAM, L; Northern Arizona University; Northern Arizona University; Northern Arizona University; Moss Landing Marine Laboratory jm348@nau.edu

The kissing gourami Helostoma temminkii, are members of the monotypic family Helostomatidae (Anabantoidei), characterized by their unusual jaw morphology and associated "kissing" behavior. However, the jaws in this species appear to be additionally modified to enable scraping algae from the substrate. We quantified the cranial movements produced during feeding in Helostoma and in two gouramis from the closely related family Osphronemidae: Betta splendens and Trichogaster trichopterus. We observed that Helostoma will take attached food by scraping it from the substrate or detached food by capturing it between the upper and lower jaws from the water’s surface or from the tank bottom; they will rarely take it from the water column. Helostoma appear to produce very little suction while feeding; food was only drawn into the buccal cavity after being encompassed by the anterior jaws, and was never drawn into the buccal cavity from a point anterior to the mouth-gape. Correspondingly, Helostoma produced very little cranial rotation (~6 deg.) and hyoid depression (~4%) during scraping ; although they produced somewhat more when removing unattached food from the bottom of the tank (~10 deg. and ~12%, respectively). Trichogaster produced similar rotation and hyoid depression to Helostoma when feeding on dettached prey resting on the bottom. However, Betta produced substantially more cranial rotation (~16 deg.) and expansion (~22%) when suction-feeding in the water column. We suggest that the highly-modified jaw morphology of Helostoma is associated with a reduction in suction feeding performance, potentially to the extent that they are unable to produce the buccal expansion necessary to capture prey from the water column.