Along the sides a pressure sensitive lateral line is well developed to sense the proximity of other fishes and surrounding structures- no doubt useful in the submarine caves where coelacanths pass their days. Two back, or dorsal, fins and one protruding beneath the nape of the tail are complimented by paired lobed pectoral and pelvic fins. These contain in their trunks bones mimicking those of Eusthenopteron which later developed into arms and legs. Used under water their action maintains stability and balance. But in their cousin Eusthenopteron, the same action became four-legged land walking.
Coelacanth scales are thick, and lined with serrated rows of hardened toothpick-pointed denticles.
Perhaps most distinctive of all is the trilobated tail with its extra trunk and fin protruding from the middle. It was this feature that made fossil coelacanths so easily recognizable and helped clinch the case for the identification of the first living specimen. While the living coelacanths retain many ancient features they have also, contrary to their public image, done some evolving along the way. Live bearing, for example, would seem to be a modern feature.