Fish Learning

By Bill Hauser

Beginning this past summer, I have been proud to recite that 2015 marked my first centennial anniversary of studying and learning about fish… and I am still learning. Most recently, today. A minor article in an emailed document alerted me to what appears to be the discovery of a newly-identified fish species, a small shark.

This actually presents a small dilemma for the answer to the perplexing question, ”how many species of fish exist in the world?” I have found counts or estimates from 24,000 to 27,300, to 32,000, to 32,800 species. So, to one of these, we must now add one more.

We certainly do not have much to go on. This is one specimen. A newly hatched juvenile. Less than 6 inches long. It was caught in deep water in the Gulf of Mexico off Louisiana. Only one other similar specimen has been caught. It was nearly 3 times larger and was caught near Peru, 36 years ago. These have not yet been deemed to be the same species but rather, they are closely related. They are called “pocket” sharks because they have small pocket-like sacs located just behind and above their pectoral fins. They belong to a larger group called “cookie-cutter sharks” because the structure of their mouth and teeth allows it to prey on larger organisms by simply snatching a bite of flesh. The bite or scar is neat and nearly round in shape – as if it had been cut out by a cookie cutter.

Folks, this is real stuff. How could anyone make this up?

The reality of all this is merely a reflection of my motto: all fish are interesting; some are just more interesting than others (and this may change daily). But there is a much bigger picture here. Fishes, as a group, comprise more number of species of vertebrates than any other group. And, as we see here, the more we explore, the more species we count. What does this mean? Fishes have been able to exploit and evolve into all available habitats in our ecosystem.