Functional Morphology and Developmental Biology of Zebrafish: Reciprocal Illumination from an Unlikely Couple

Abstract

Functional morphology has benefited greatly from the input of techniques and thinking from other disciplines. This has been especially productive in situations where each discipline has made significant contributions to a particular research topic. A combination of methodologies from functional morphology and developmental biology has allowed us to characterize feeding mechanics of first-feeding larval zebrafish (Danio rerio). Contrary to kinematic patterns commonly seen in adult teleosts, larval zebrafish showed no lateral abduction during the expansive phase of a suction-feeding event. Instead, dorsoventral expansion of the buccal chamber, more typical of patterns seen in primitive fishes, characterized the expansive phase. Moreover, a pronounced preparatory phase during which the buccal chamber is constricted by the protractor hyoideus was consistently seen in first-feeding larval kinematics. Key kinematic variables associated with first feeding correlated significantly with the hydrodynamic regime as measured by the Reynolds number. Using the tools of both functional morphology and developmental biology we have not only determined which cranial muscles are important for successful feeding but also uncovered important physiological differences in muscle structure. Muscles necessary for the rapid dorsoventral expansion of the head are composed primarily of fast-twitch fibers while those involved in more tonic contractions such as hyoid protraction have more slow-twitch muscle fibers. While most evolutionary developmental studies have examined mechanisms responsible for large evolutionary changes in morphology, we propose that the type of data uncovered in functional studies can lead to the generation of hypotheses concerning the developmental mechanisms responsible for smaller intra- and/or interspecific changes.

The development of zebrafish tendon and ligament progenitors

“…Studies of feeding mechanics of larval zebrafish identify three main phases of the food strike, which primarily involve the depression of the hyoid arch through the contraction of the sternohyoideus. Additionally, it is thought that the muscles attaching to the cleithrum help to prevent its anterior displacement, which allows efficient opening of the buccal cavity (Hernandez et al, 2002). Interestingly, the major regions of overlapping scxa and tnmd expression are found exactly at these attachment points, where the sternohyoideus muscles meet the ceratohyal cartilages and where the sternohyoideus attaches to the cleithrum.…”

A jump persistent turning walker to model zebrafish locomotion

“…The fact that zebrafish locomotion is better described through the inclusion of jumps highlights well-known effects of morphology on swimming [47,48]. In particular, fish must accommodate the constraints imposed by viscous and inertial forces of the water.…”

Genetic and developmental basis of cichlid trophic diversity

“…Zebrafish are obligate suction feeders characterized by thin elongate mandibles, used to feed on small aquatic insects, crustaceans and plankton (see Hernández et al, 2002 for characterization of zebrafish feeding kinematics). At pharyngula stages of development, little bmp4 was found in the zebrafish mandibular arch (Figure 6c).…”