Nov. 26, 2012

Strange Fish

by Kara Rogers

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Dr. Seuss's McElligot's Pool (1947) features some fantastic fish—ones with pinwheel-like tails, curly noses, long floppy ears, or Kangaroo pouches. While a bit far-fetched for fact themselves, those fictional fish do have some truly strange nonfictional cousins, among which are giant oarfish, barreleye fish, and sawfish.
The giant oarfish (Regalecus glesne) looks like a sea serpent, and in fact it likely was the legendary creature featured in many a sailor's tale. It averages about 10 feet in length, making it the longest known species of bony fish in the world, and it has an eerie silvery body that is adorned with a bright pinkish to fire-red dorsal fin. It is thought to be widely distributed, occurring in most oceans with the exception of those in the polar regions. Because it lives between 1,000 and 3,300 feet below the ocean's surface, however, it is seldom seen at sea. Dead giant oarfish occasionally wash up on shore, giving people a good scare, and the species is sometimes seen swimming in shallow waters frequented by herring, giving the impression that it associates with the smaller fish. That mistaken notion explains its other common name, the king of herrings.
Barreleye fish (family Opisthoproctidae) can give observers a thorough fright as well. These creatures have transparent windshield-like coverings on their heads and are so shocking and creepy that they are sometimes referred to as spookfish. The fluid-filled space beneath the shield houses tubular eyes that contain thousands of reflective plates, which are positioned at different angles and act like mirrors to focus light on the retina. The complex structure enables the fish to keep its body horizontal while looking up and down at the same time, forming clear images of prey swimming above in the downwelling light and of zooplankton and other prey sinking in the water. Barreleye fish are relatively small, measuring about half a foot in length, and inhabit areas of the Atlantic, Indian, and Pacific Oceans.
McElligot's Pool features a sawfish that has a sawlike snout so long that it needs another fish to carry it. While real sawfish (family Pristidae) do not of course require such assistance, they do have long snouts (or rostrums) that look remarkably like the blades of chainsaws, lined on each side by two or three dozen sharp teeth that project outward. Sawfish, which are a type of ray, can grow to 15 feet or more in length, with the rostrum accounting for more than one-quarter of that length.
Unlike oarfish and barreleye fish, sawfish are not found in the depths of the sea. Rather, they are found near shore in both freshwater and saltwater habitats, and they sometimes swim far upriver and lurk in mud in river bottoms. Despite their proximity to humans, the likelihood of people encountering sawfish in the wild has declined significantly, because the animals have been hunted to near extinction. All seven recognized species of sawfish are now considered to be critically endangered.
Maybe no human could have imagined the types of fish that inhabit Earth's aquatic environs, but Dr. Seuss came pretty close with some his creations in McElligot's Pool. The book serves mainly to encourage children to use their imaginations, but to me it also carries a message about the importance of not writing off the existence of improbable creatures. Indeed, as marine biologists have shown us (and shown us), the world's oceans, lakes, and rivers are full of strange and wonderful life.
About Kara Rogers

Kara is a freelance science writer and senior editor of biomedical sciences at Encyclopaedia Britannica, Inc. She is the author of Out of Nature: Why Drugs From Plants Matter to the Future of Humanity (University of Arizona Press, 2012).

The views expressed are those of the author and are not necessarily those of Science Friday.

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