Category:

SEX CATAPULTS!

by Ben Taylor

Catapults: They're amazing! Stored potential energy rapidly released as forward motion to launch missiles, basketballs, watermelons, and even flying cars through the air. We know them, we build them, we love them. But humans are not alone in our adoration of the contraption, for while nature may abhor a vacuum, she loves a nasty catapult. And nature puts catapults in one fun place in particular—namely, the bodies of arthropods.

Arthropods, from Greek for "jointed foot," are a group of animals made up of insects, crustaceans, spiders, and the various creepy-crawlies of the planet. The jointed limbs in the hard chitinous exoskeletons of arthropods act as ideal spots for springs, locks, and hydraulic mechanisms that release stored energy in a near instant when triggered. Arthropods are catapult creatures.

Take, for example, the extreme release of stored power in the bite of the trapjaw ants. Hundreds of different ant species have evolved a mechanism in their mouths similar to a bow and arrow, which latches open their mouthparts when they're awaiting prey or preparing to escape a threat. When triggered, the mandibles snap shut at speeds up to 2,300 times faster than a blink of a human eye. This allows for the instantaneous snagging of food, or in some cases an evasive maneuver where the ant releases its jaws against the ground to launch itself through air and away from danger.

Most arthropodal catapults, called modes of kinematic transmission, have evolved as a means of both predation and defense. But in April 2022, a paper published in Current Biology changed everything. Scientists at Hubei University in China, writing about the male hackled orb weaver spider, described a behavior that very much utilizes catapults for sex. Why does the male hackled orb weaver care about catapults during sex?

To start, the female hackled orb weaver spider is way larger than him—nine times larger. As if that didn't make sex intimidating enough, the female hackled orb weaver spider engages in post-coital snacking, mainly on her male partner. This George Costanza-esque sexual cannibalism is seen in many size-dimorphic pairings, perhaps most famously with the praying mantis (for with praying mantises, the male is always giving head), and is an extremely efficient way of getting extra protein for egg production. It's just not super ideal for the male if he wishes to live and mate another day. So this hackled orb weaver spider has evolved a very special catapult, on a very special part of his body. And we're not talking about boner stuff. We're talking hydraulics, another catapult-friendly aspect of the bizarre and beautiful bodies of arthropods.

Instead of typical veins and capillaries, arthropods push blood and fluids through their system using a massive tubular heart that stretches the length of their bodies. Imagine squeezing a condom full of blood. Go on. Imagine it. When you squeeze that extra-large condom full of red, red blood, you force fluid to rocket to the parts of the condom outside the zone of your squeeze. You force those portions of the condom to quickly expand with the force of the sudden hydraulic pressure of your squeeze. You have made a liquid catapult of sorts, and this is how nature makes it happen with male hackled orb weaver spiders.

This catapult is on the spider's skinny front legs, each thinner than a human hair. During copulation, the male hackled orb weaver bends its jointed legs against the mounted female, as though preparing a tiny push-up against her. When mating is over and mealtime set to begin for the female, powerful muscles in the male spider's thorax smash body fluids into its folded forelimbs, and the resulting hydraulic force catapults the spider off the female at speeds up to three feet per second. The male lives to mate another day, and scientists even observed one male catapulting his way out of bed six times in eight hours. Not bad, little male hackled orb weaver spider.

And that is the beauty of arthropods. All that potential hydraulic energy, just sloshing around: might as well force it into a forelimb so you can escape from bed without having to be the post-sex room service as well.

by Aerie Shore

Cephalopods—denizens of kingdom Animalia, phylum Mollusca, class Cephalopoda—are the most intelligent and behaviorally sophisticated of the invertebrates. Their ancestral lineage surfaced a mind-blowing 500 million years ago, and that generous girth of evolutionary time has endowed them with anatomical superpowers and thrilling attributes. Come with me on a cephalop-odyssey, as we briefly visit the seven presently acknowledged extant orders of these magnificent underwater weirdos.

Diving in hypothermia-inducing winter waters near Whyalla, South Australia, I had the profound pleasure of witnessing the mating rituals of giant Australian cuttlefish. Larger males compete for mating rights in flamboyant, Technicolor displays of mightiness. Males too small to contend in these showdowns of cephalopodic machismo utilize a clever tactic, earning the nickname "sneaker males." Sneakers tuck in their telltale, sexually dimorphic arms and disguise their coloration to mimic female appearance. Such subterfuge enables them to surreptitiously sidle up to a potential paramour, reveal their true sex, and get it on in a tentacular face-to-face mating embrace. Cuttles have eight arms and two tentacles. If you think making the beast with two backs is boastworthy, try making the beast with 20 appendages. Think naked underwater Twister with four of your more adventurous friends. For science!