Divergence in skeletal mass and bone morphology in antarctic notothenioid fishes

Cover illustration. Notothenioid fishes lack swim bladders, but species live temporarily or permanently in the water column. Without swim bladder, skeletal mass becomes a key determinant of buoyancy. In this issue of the Journal of Morphology, Joseph Eastman and coauthors (pp. 841-861 10.1002/jmor.20258) quantify the degree of skeletal ossification in notothenioid fish and discuss it in phylogenetic context. The cover image shows a volume rendered micro-CT image showing extensive bone in the adult skeleton of the non-Antarctic notothenioid Bovichtus diacanthus from Tristan da Cunha. Tissue density is mapped in false color on a spectrum ranging from less dense (cool colors) to more dense (warm colors). Bone is considerably more extensive in B. diacanthus than in Antarctic notothenioids.