The mustache is an accessory of great responsibility, for with it comes great power. Take, for instance, Tom Selleck in Three Men and a Baby, Alex Trebek in pre-2001 Jeopardy, and Freddie Mercury in all of eternity forever and always. Facial forces to be reckoned with, for sure, but to the best of my knowledge none of these men has ever maimed a rival with the mustache itself.
Amateurs, says the Emei mustache toad. This dapper little amphibian doesn’t just walk into the breeding season unarmed. For one chaotic month a year in China, males grow extremely sharp facial spikes, which they use to shank rivals for the choicest nesting sites.
Some 90 percent of all males end up injured. Victors win the right to mate. Losers shuffle away and seriously consider never growing a mustache again, because maybe it wasn’t a good idea in the first place and they were just curious how it would look, like that one time when I was in high school.
Their weapons are called, no joke, nuptial spines, and they’re made of keratin — the same stuff as your fingernails. The spines grow straight through the toad’s skin, and although they will at times pop off in combat, they’ll simply sprout once again, only to fall off at the end of the breeding season.
And if you think that mustache is handsome, wait until you hear about the toad’s other transformations. Its forearms will actually buff up considerably in the mating season, like a bro during a Jersey Shore summer. This, according to evolutionary biologist Cameron Hudson, likely aids both in combat and in amplexus: the amphibian sexy-time, in which strong forelimbs will help the male grasp the female.
In addition, “their skin also becomes much looser, folded, and wrinkled,” Hudson said in an email to WIRED. “We think that this transformation allows them to remain underwater for longer periods (since the breeding, combat and nest guarding is all aquatic) by increasing oxygen absorption through the skin’s larger surface area.”
This species is, after all, a terrestrial one that like most frogs and toads chooses to reproduce in water, which is ideal for their external fertilization. Males hole up in nest sites, the most sought-after being caves of overhanging rock where eggs can be safely deposited. Periodically surfacing to breathe, they will defend these dens zealously like tiny Smaugs, only without the fire-breathing on account of being underwater.
“Generally the battles occur when one male approaches the nest site of another male and tries to go in through the entrance,” said Hudson. “They usually start with the nest occupant trying to block the entrance and shove the intruder away with their head (also while vocalizing). As the fight escalates the intruder will try to grapple the owner and rotate him out of position.”
The combatants keep their heads low, aiming to flip one another. “Usually the fight ends when a male holds his opponent vertically,” added Hudson, “grappling him around the waist and stabbing him in the abdomen. The ‘grappler’ tries to bash his opponent against nearby rocks.”
These battles are vicious, as you can see in the video below. Strangely, though, losing doesn’t necessarily doom a toad’s chances of mating. “There are some potentially interesting questions about male strategy that came up during my research,” said Hudson, “in that fighting is energetically expensive, so sometimes it might be in your best interest to lose and find a new site (if they are available).”
What tends to reverse that size bias are selection pressures on the males to grow larger to fight for the right to mate, as Hudson believes the mustache toad has done. Though Hudson finds that being big doesn’t always guarantee victory in battle, large males do indeed have the highest reproductive success. This indicates that females prefer their fellas bulky, or that while larger males can suffer loses, they’re generally better able to control nest sites.
Here’s how it all goes down. When females show up to the river-bottom breeding grounds, the males call out, ideally from the comfort of a sweet nest. If a female is interested, she’ll approach and bump him on the chin with her head, as if to say, “I’m not one of those girls who hates mustaches.” He’ll then rub his chin back and forth across her head — which Hudson reckons is some sort of stimulation — as the pair moves around the nest for the female to scope the surroundings.
“Once they have decided to mate, the male grasps around [her] hips and turns sideways,” said Hudson. “As she begins to lay the eggs, he sticks them to the roof of the nest with his foot. The pair then rotates in a circle, which creates the distinct doughnut-shaped egg mass.”
But say you don’t find your nest before the females arrive. Interestingly, if a male and female have already done that tango and a new male shows up and evicts the successful male, he won’t destroy the already-fertilized eggs. This is quite strange from an evolutionary perspective: Helping protect offspring not of your own making is a waste of energy, not to mention that the young will compete with your own.
Hudson theorizes a few reasons why this may be. “The first is that females may prefer nests with eggs. It’s possible that they take this as a sign of a successful male, and good breeding partner. Another reason may be that if you have more eggs in the nest, yours are less likely to get eaten by a predator, or infected by water molds.”
Read more at Wired Science
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