Biophiliac: A Fish Tale

By Leslie Anthony.

There are many things in this world that make you go “Hmm…” Some fall into the category of inexplicable human actions (e.g., littering, murder, conservatism – oh hell, let’s throw increasing carbon emissions in the face of certain climate change in there as well), challenging our understanding of our species. The lion’s share of entities termed wonder-inducing by humans, however, stem from the realms of physics, chemistry and, most often, the organic world of plants and animals. Reasons for the latter are manifold, but best summed by our affinity to – and sense of place in – the natural order.

There’s a word – biophilia – that describes this instinctive bond between humanity and other living systems. Famously coined and elaborated by the evolutionary ecologist E.O. Wilson in an eponymous book, this relationship – comprising a spectrum from our anthropomorphic connection with baby animals to the calming effects of a forest – is what this new column intends to explore.

Shinto shrine in Togakushi, Nagano Prefecture, Japan.
Shinto shrine in Togakushi, Nagano Prefecture, Japan.

As a biologist and science journalist I am familiar with many of Mother Nature’s more byzantine aspects and I find myself less surprised by the wonders gurgling up from nature’s depths than the litany I’ve already absorbed. For example, I know that an Australian frog (now sadly extinct) could turn off its digestive juices, swallow its tadpoles, and raise the kids in its stomach; I understand that flamingos are pink because of pigments sequestered from the shrimp they eat; and, by passing a particularly tough genetics exam, I have subsumed the arcane knowledge that although some of the DNA in booze-producing Saccharomyces yeasts is gene poor, repetitive, and transiently silenced, it nonetheless evolves rapidly due to transposon activity, increased recombination and a surprising level of nucleotide divergence (hence the many kinds of wine and beer brewing). All this is cool in its own right, of course, but the demonstrable relationship by descent of humans to flamingos and gastric-brooding frogs – even yeast (not to mention our making beer together) – is positively pride-inducing. Yay team.

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Not all organisms spark such instant affection. Who, for instance, has ever understood those miserable little metallic commas found, even in the most fastidious of bathrooms and kitchens, surreptitiously circling faucets and scuttling over countertops? No one, yet they’re as seemingly mundane in our lives as junk mail. So I put it to you now with appropriately Seinfeldian succinctness: what’s up with silverfish?

Illustration by Dave Barnes.
Illustration by Dave Barnes.

These denizens of darkness, exclusively revealed when you flick on a light, are always a nasty surprise. Perhaps not the horrifying revelation of a rat, or the gross-out of a cockroach, but begging similar questions. Where did they come from? Do they bite? Do I have an infestation? But here’s the real question: what’s up with a critter that according to Carboniferous fossils has lurked in identical form for some 300,000,000 years but whose natural habitat now seems to be my sink? The animal hasn’t changed, but something’s fishy. Hmm…

Predictably, the explanation is a good news/bad news scenario for biophiliacs.

Good: although sink-and-bathtub-sightings of silverfish are a worldwide phenomenon, most involve a single ubiquitous species – Lepisma saccharina, a small, wingless insect of the order Thysanura. Lepisma have primitive mouthparts, don’t bite, and don’t spread disease. Best of all, in light they’re defenseless and, as you’ve likely discovered, easy to squish, leaving an insubstantial smear not unlike that found under your fingernails after playing Scratch ’n Win.

Bad: also called fishmoth, carpet shark, or paramite depending where you live, “silverfish” (in use since 1855) combines colour with the piscine movements of the animal’s well-jointed body, while the scientific moniker (traceable to 1758 and the father of modern taxonomy, Carl Linnaeus) refers to its diet of simple polysaccharides – sugars and starches found not just in the food stores it happily infests, but in glue and adhesives, book bindings and paper; in carpet, clothing, cotton, silk, leather and synthetics; even in body exuvia like hair and dandruff. In short, 21st century humanity offers silverfish an unparalleled smorgasbord: they’ll eat your pancake mix, leave holes in your clothes, destroy your books, and even set off fire alarms (a measurable percentage of fire department false alarms can be traced to the short-circuiting of alarms by peckish silverfish).

Silverfish, ready for your smorgasbord.

Good: it’s not just your house. Like fleas, silverfish have accompanied human habitation since it began – wild Lepisma favour caves and other dank areas with high humidity (I found one for the first time ever in the wild this past summer). You find them in sinks and bathtubs not because they live there, but because their Carboniferous-crafted appendages do poorly on the modern world’s smooth surfaces; they’ve simply become trapped there, attracted by the moisture and food prospects rising from your drains (de facto encouragement to keep these clean).

Bad: unlike more ephemeral insect pests, an unsquished silverfish can live out of sight in your home for up to eight years and go a full year without food (starting to be impressed…)

Good: reproductive rate is low; a single female lays fewer than 100 eggs in her lifetime. These can take months to hatch; if they dry out they’re toast.

Bad: predators of silverfish are fellow cave-happy things you aren’t psyched about seeing around the house: spiders, earwigs and those über-creepy, long-legged house centipedes known as scutigers.

Scutigers are also frequently found “stuck” in sinks and bathtubs because they were hunting silverfish. That’s cool, and knowing it will make me think twice before I squish them. Sometimes a little knowledge is a terrible thing. Hmm…