Off-campus UMass Amherst users: To download dissertations, please use the following link to log into our proxy server with your UMass Amherst user name and password.
Non-UMass Amherst users, please click the view more button below to purchase a copy of this dissertation from Proquest.
(Some titles may also be available free of charge in our Open Access Dissertation Collection, so please check there first.)
The effect of a cartilaginous skeleton on form
Abstract
The skeletal elements of cartilaginous fishes are composed of a thin layer of mineralized tissue, ‘prismatic cartilage’, overlaying a hyaline cartilage core. Cartilage, even with a surface layer of mineralization, is far less stiff and strong than bone. Nevertheless, several species of stingray, including Rhinoptera and Aetobatus, subsist by crushing hard-shelled mollusks and crustaceans in their cartilaginous jaws. The jaws of these stingrays are composed of a previously undescribed form of cartilage. This tissue, ‘trabecular cartilage’, has mineralized struts which run through the central hyaline core. The struts, or trabeculae, are hollow tubes, made of calcified blocks, arranged as in a brick chimney. They serve to prevent buckling and bending of the jaws while prey is being crushed. The struts are present in late term embryos, indicating that feeding on hard prey does not cause them to form. As the animal grows the struts lengthen and thicken though they do not appear to become more numerous. Trabecular cartilage appears to have evolved at the base of the clade containing the hard prey specialists. This clade also includes Manta, a planktivorous species, which retains trabecular cartilage.
Subject Area
Zoology|Anatomy & physiology|Animals
Recommended Citation
Summers, Adam Parsons, "The effect of a cartilaginous skeleton on form" (1999). Doctoral Dissertations Available from Proquest. AAI9932348.
https://scholarworks.umass.edu/dissertations/AAI9932348