Sam Van Wassenbergh

Within the family Clariidae or air breathing catfishes, several species have developed unusually large (hypertrophied) jaw closing muscles. The extremely hypertrophied morphs (C and D of the figure on the left) have jaw adductors with physiological cross-sectional areas of up to 7 times those of the non-hypertrophied morphs (for a given skull length).

Inevitably, the extreme variation in this component of the cranial musculo-skeletal system will have important consequences on its function during feeding. Biomechanical modeling has shown that species with enlarged jaw closers can theoretically produce a higher maximal biting force (Herrel et al., 2002). However, biting is only one of the many functions of the cranial musculo-skeletal system in fish. As the hypertrophied jaw muscles also strongly interact with the suspensorium and the neurocranium, effects on the structure and mechanics of the bucco-pharyngeal expansion apparatus (responsible for prey capture, -transport, -processing, aquatic respiration and air-breathing) are expected. The aim of this study is to investigate the consequences of jaw closer hypertrophy on feeding in clariid catfishes.

Species shown in the figure:

Clarias gariepinus (A)

Clariallabes longicauda (B)

Gymnallabes typus (C)

Channallabes apus (D)