Understanding morphology: a comparative study on the lower jaw in two teleost species

Zebrafish are currently used as a model organism for studying disorders affecting bone development and regeneration, yet we do not understand many aspects of teleost skeletal biology. This study focuses on the changes in shape of Meckels cartilage and its subsequent ossification in two teleosts with different feeding strategies and jaw morphologies; zebrafish (Cypriniformes) which lack mandibular teeth and the sighted Mexican tetra (Characiformes), which has oral teeth. We find that some aspects of jaw development, such as the retraction of Meckels cartilage are delayed in the tetra despite its larger embryonic and adult size, while other aspects, such as the differentiation of mature chondrocytes is accelerated. The mode of retraction of Meckels cartilage also appears to be different in tetra compared to in zebrafish. Understanding the cellular and developmental mechanisms underlying jaw shape in species with different feeding strategies is important to our understanding of vertebrate morphology in general, and could provides novel insights into teleost skeletal biology.