Fun with the fishes

kw: book reviews, nonfiction, fish, ichthyology

These two little fish, a lanternfish above and a bristlemouth below, may be the most abundant animals on earth. They live about a kilometer deep in the sea, and there are probably a few million billion (that is, about 5,000,000,000,000,000) of each in the sea. That is, around a million of each of these little fish per living human. That is about equal to the total number of termites on (and in) land. This picture shows them around half size, so they are much larger than termites. If there are 1,000 pounds of termites per person, there are close to 1,000 tons of just these two fish, per person. According to this article, one genus of bristlemouth is the most abundant, edging out the lanternfish.

Other fish aren't quite so abundant. Oh, there are a lot of fish in the sea, but not nearly as many as there were before industrial fishing began in the 1800's. Small, bony, bad-tasting fish like bristlemouths haven't been affected, but many, many other kinds of (tasty) fish are only about 1/10th as abundant as they were 100-200 years ago. Further, many kinds of less-tasty ones are destroyed as bycatch, caught in the nets and trawls and discarded dying or dead.

This Gulper Eel is in the running as "ugliest fish", but I think it rather charming. It's a sure bet that Gulper Eels like each other, at least around breeding time, no matter what we might think of them. Fish in general are fascinating. While I like going to a zoo to see the mammals and birds, I adore aquariums. They are just a bit more scarce, and cost more to run, yet are incredibly popular in spite of higher admission fees.

Eye of the Shoal: A Fishwatcher's Guide to Life, the Ocean, and Everything, by Helen Scales, just touches the surface of the huge variety of fish stories that could be told. She tells us a bit about how many major groups of fish there are and what they are like, and discusses ten fish-related subjects, in an enjoyable, readable way. And I must mention the illustrator, Aaron John Gregory.

Ask anyone, "What does a fish look like?", and you'll probably get a description that is pretty much like this yellow perch. You can catch these lovely, pan-size fish in many lakes and streams throughout North America. You could make a checklist: Longish oval shape, a fin or two on top and bottom and sides, scales, forked tail, and so forth. Ninety percent of all species of fish are kind of like that, and are called Teleosts ("perfect bone") or "ray-finned" fish.

But some fish don't have bones. Think sharks, skates, and rays. Their skeleton is composed of cartilage, like the easily broken stuff that gives your nose its shape. Some don't have scales, such as eels (well, actually, they have very tiny scales) and adult swordfish. Some fish, though they have bones, don't have jaws. Lampreys and hagfish are the best known (but maybe you never heard of them). Some fish have few bones; a spine but little else, such as puffer fish.

And by the way, fishes of the most common genus of puffer fish, Tetraodon, contain extremely poisonous tetrodotoxin in parts of their bodies, making them the most dangerous fish to eat. Even with strict licensing of sashimi chefs in Japan, every year a few people die from eating puffer fish called fugu that weren't quite prepared right.

For most of us, our main exposure to fish outside of a public aquarium is in the kitchen or restaurant. Most people enjoy eating fish, and the local grocery store usually has a fish counter where you can buy salmon, perch, tilapia, and perhaps trout, bream, and maybe catfish…plus various non-fish such as clams, shrimp and mussels. About 3/4 of the world's people get most of their protein from fish, which is why so many species of popular fish are seriously overfished.

There is a chapter near the end of the book that discusses this problem, and the lack of any useful solutions. Fish farming can make a certain amount of difference, but probably not enough. Along with all the other dangers we cause because of the sheer number of people on Earth, we are eating our way to eventual starvation for many.

I can't end this without one more picture, this time of the biggest fish it is safe to approach, the Mola Mola sunfish. This one is a "mere" 10 feet "tall" (fin tip to fin tip); they get as large as 14 feet and weigh up to 2.5 tons. Ocean sunfish are curious about people and not aggressive.

With some 20,000 species, fish are the most abundant vertebrates. This book just whets the appetite for learning more and more about them.