Meeting Abstract
Vertebrates span an incredible range of shapes from almost spherical to spaghetti-like. At one extreme of this possible range are the highly elongate groups, which make up a significant portion of many vertebrate groups. Several studies have noted that body elongation is often coupled with an increase in the number of vertebrae, usually in one specific region. In general, actinopterygians have increased vertebral number in the caudal region whereas increases occur in the precaudal region in sarcopterygians. For fishes, the caudal region of the axial skeleton, is key to understanding potential for locomotor performance as more segments increases the flexibility of the body. In this study, we focused on Ophidiiformes, a group of actinopterygian fishes that include relatively elongate species. We measured 13 morphological and meristic characteristics from 14 species. Through this work we sought to answer 3 questions: 1. What are the relative changes in the length and depth of the caudal vertebrae, 2. How does decreases in the depth of the vertebrae correspond with decreases in body depth, and 3. How does second moment of area (I) change along the caudal region? We found three distinct patterns for variation in the caudal region. We show that species differ in the relative decrease of the vertebrae along the caudal region as well as the degree of tapering of the tail. Finally we found that while I decreases posteriorly along the caudal region for all members of the group, Dicrolene introniger, had the lowest I. Chilara taylori had the greatest I, indicating a relatively stiffened tail. Given the unique ecology of several of ophidiiform species, this study allows us to further interpret how changes to the caudal region affect locomotor performance and lifestyle in these interesting and highly elongate fishes.
