The Paradoxical Seahorse, Hippocampus paradoxus, is a recently described species from the Great Australian Bight (Foster and Gomon, 2010). Known only from a single specimen collected in 1995, this small species breaks the planning rules of seahorse anatomy. It is the only known seahorse without a dorsal fin, instead having a series of fleshy lobes down the back and tail. It also lacks the rigid external bony plates that characterise most seahorses. The numbers of plates ringing the body and tail of a seahorse are key taxonomic (identification) features but were very difficult to determine in the specimen because of the fleshy dermis. To visualise the remnants of the rings and other features hidden beneath the skin, South Australian Museum researchers turned to micro-CT scanning. The technique proved to be remarkably useful allowing detailed, non-destructive examination of not only the skeleton but some soft tissue features, as well, such as unlaid eggs in the abdomen. Some of the CT scan images used to scientifically describe Hippocampus paradoxus are presented here, along with CT scans of two other seahorse species, H. breviceps and H. denise, for comparison.
Foster, R. and Gomon, M. F. (2010). A new seahorse (Teleotei: Syngnathidae: Hippocampus from south-western Australia. Zootaxa 2613: 61–68.