Living Fossil - Keith S. Thomson

The coelacanth is a type of fish that was presumed extinct since before the dinosaurs died out, until one was caught and identified scientifically in the late 1930s off the coast of South Africa. It was a new species, not one of the fossilized species, but still a big deal. Thomson details the history of that find and the subsequent search for more individuals and more information.

The book was published in 1991, so its information ends in the 1980s. At that point, the individual found in South Africa was the only one found anywhere other than the Comore Islands. This factors into other parts of the book, where Thomson details the territorial view that descends as scientist from around the world want to catch and dissect their own coelacanth. One problem being, with so little information on how many there were, how large their range was, how quickly and abundantly they reproduce, there was a possibility the mad dash for coelacanths would wipe them out. At the very end, Thomson suspects Latimeria (the genus of this particular coleacanth) might be the first made extinct by scientists.

(Wikipedia tells me there are now two recognized extant species, one around the Comores and East Africa, the other around one island of Indonesia.)

The middle of the book is devoted to detailing what scientists had actually figured out about Latimeria, and how, given the limited number of specimens and how rarely they'd been observed in the wild (at that time, limited to Hans Fricke getting a submersible and recording them). Thomson discusses how aspects of the fish's anatomy resemble those found in other species, and how this enabled them to confirm the depths it likely lives at. The eyes of all the captured specimens had a milky coating, not present in the videos from the sub. Scientists were able to figure out the coating was the eyes being damaged by the pressure change as the fish was hauled to the surface.

There's a large section of one chapter devoted to the question of reproduction, based on inference from observations of Latimeria ovaries versus other fish. Do males and females release a bunch of eggs and sperm into the water and just roll the dice, or does the female carry fertilized eggs for a time internally, or is it live birth? Granted that without field observations, comparing them to what sharks or other fish do is almost guesswork, but Thomson's thorough without getting too bogged down in technical discussion about how they find as much evidence as they can to support a hypothesis.

'Everyone agrees that coelacanths were not the immediate ancestor, so they don't have quite the pride of place that one would like. But they are one of the only four genera of living lobe-finned fishes to remain out of the great Devonian radiation of lobe-finned fishes that was crucial to the matter.'