Boxfish: Little Fish, Big Toxins

The boxfish.

Most of the time, I use this blog to blather on and on ceaselessly about all the things about life on this planet I find inescapably fascinating. While all of my exposition on killer fungi, badass birds, weird plants, or whatever obscure, bizarre, horrific, extinct monstrosity wandered into my search history that week is charming (obviously) and fun and all, I don’t often indulge in not only talking about the things that I think need to be shared, but things that are also very directly related to my scientific, academic interests. But, today I shall pander to myself and the relatively narrow realm that constitutes my research interests in the hope that you, dear reader, can push through the voluminous, insatiable outwards expansion of my own ego and acknowledge that my currently proposed study organism for my PhD research, the proud, doughty boxfish…is pretty goshdarned fucking cool.

While I plan on investigating certain nuances about the genetics and evolution of this special group of fishes, the topic of this post isn’t on the subtleties of things like gene flow between populations and speciation, but instead on an incredible, noxious, chemical adaptation that is unique to the boxfish.

But first…what exactly is a boxfish? Boxfish are small fish (between about 5 and 18 inches long, but most are at the low end of that range) that frequent the shallow areas of the warmer parts of the world’s oceans, like coral reefs and seagrass beds. They spend their lives passively pruning algae and small invertebrates like crustaceans, worms, and sponges off rocks and coral with their tiny, delicate mouths. They, as a group, are united in having a body made conspicuously rigid with hexagonal, bony plates fused together to form a hard, yet light-weight shell that encircles their interior, “real” skeletal framework. This shell (which has recently been used as bionic inspiration for automobile design) often has modestly rounded corners, and makes the animal distinctly rectangular in overall shape…hence the “boxfish” name (many species are also referred to as “trunkfish,” and there a some species with preposterously unintimidating horns called “cowfish“). This is an animal that is too hip not to be square.

So, this full-body shell results in the boxfish having a skeleton that essentially looks like a decapitated skull. Similarly to a skull, there are precious few holes in the cage of bone, and the formidable armor only opens up for the eyes, puckered mouth, fins, and tail to peek out into the water. When desiccated corpses of boxfish wash up on beaches, their remains resemble the forgotten, bleached craniums of ill-fated livestock out of a stereotypical, “harsh” cartoon desert.

Photo taken shortly before a tumbleweed rolled into the frame.

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