O’NEILL, M.W.*; GIBB, A.C.; Northern Arizona University; Northern Arizona University: Feeding and Respiration in Trinectes maculatus: Half a head is better than one
Flatfishes have evolved a benthic lifestyle, where both eyes are present on one side of the head as adults. This results in marked morphological asymmetry, especially in the head and mouth. Hogchokers, Trinectes maculatus (Achiridae), live in both fresh and salt water in soft bottom habitats. We recorded hogchokers feeding on bloodworms using a Redlake PCI 1000S digital-video system, and analyzed images using a custom digitizing program. The animals required training to feed in bright lights, suggesting that they may be nocturnal feeders that use both visual and chemical cues. A hogchoker is only able to take prey from the substrate, not from up in the water column. Buccal cavity expansion enhances suction feeding, and a fleshy flap covering the eyed side of the mouth helps direct suction toward the substrate. Ventilation appears to occur through the eyed side of the mouth and is regulated by a flap extending from the lower jaw. Prey capture is very rapid and highly asymmetrical. During feeding, the blind side portion of the mouth projects toward the substrate at approximately 75o from the midline of the animal, and prey is captured within 10ms of mouth opening. Major bones of the jaw are also highly asymmetrical, especially the premaxilla and dentary, and may be involved in producing kinematic asymmetries. These results suggest the mouth is divided into two functional units: the blind side is used for feeding and the eyed side is used for respiration.
