Labridae Fishes: Morphology, Feeding Habits and Limitations

The family Labridae, otherwise known as wrasses, is marine fish consisting of more than 575 species found in warm-temperate and tropical reefs around the globe (Wainwright et al. 2004). Of all of the coral reef fishes worldwide, the family Labridae is one of the most morphologically diverse (Westneat 1995). Due to their different morphologies, different fishes within the species prey on different types of food. The main difference making up the separate morphologies, and subsequently feeding habits, is the functional and mechanical properties of the jaw. Due to so many variations of the functional morphologies of feeding, many studies have been conducted on wrasse feeding behavior to distinguish how the different modifications of morphology have become so diversified using the same basic mechanical (jaw) feeding system (Wainwright 1988; Westneat 1995; Hulsey and Wainwright 2002; Bshary 2003; Wainwright et al. 2004). All various species within the Labridae family vary in their food preferences and specializations. Prey includes coral, shrimp, fish, hard-bodied prey, soft-bodied prey, parasites, and algae. The highly specialized nature of the feeding behavior of the wrasses is responsible for their occupation of very narrow ecological niches. In particular, we observed the genus Halichoeres in Belize, which includes the Yellowhead Wrasse, Halichoeres garnoti, as well as the Bluehead Wrasse, Thalassoma bifasciatum. This species demonstrates forceful and crushing feeding patterns. This type of feeding is derived from the morphology of its pharyngeal jaw. The jaw of Halichoeres has two muscles originating at the neurocranium extending downward and inserted into the lower pharyngeal jaw, without any joints (Wainwright 1988). Although these jaws offer extreme crushing force, the force is dependent upon many variables including the crushing force potential, the pharyngeal jaw gape, and the body length. These three factors designate whether the Halichoeres

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