Meeting Abstract

P3.72  Thursday, Jan. 6  Does Morphology Contribute to Dimorphic Feeding Behavior in Betta splendens CARLSON, Niels*; ALICE, Gibb; Northern Arizona University; Northern Arizona University nhc4@nau.edu

Betta splendens, also known as Siamese fighting fish, are a popular aquarium fish well known for intraspecific aggression. Many studies have focused on the aggressive courtship displays of Betta splendens, but few have examined other sexually dimorphic aspects of morphology or behavior. However, previous work in our laboratory has documented sexual dimorphism in feeding movements: male Betta food capture behavior is characterized by larger lower jaw depression and smaller hyoid depression, relative to female Betta. In an effort to determine if dimorphic food capture is a product of morphological dimorphism, 53 Betta splendens specimens (24 male, 29 female) were differentially cleared and stained to allow identification of bony and cartilaginous elements of the cranial bones. A preliminary examination of these specimens reveals that males have larger supraoccipital crests, which form a “hump” on the posterior-dorsal aspect of the skull. It also appears that males have more robust bones that comprise the oral jaws (e.g., maxilla, premaxilla, and dentary). Our goal is (1) to quantify morphological differences between males and females in the anatomy that underlies the production of prey capture movements and (2) to input these measurements into existing mathematical models of feeding behavior to determine if dimorphic cranial morphology is responsible for dimorphic prey capture. However, it is also possible that differences in behavior are generated entirely or in some part by central nervous system output.