Male Tropical Fish Uses Food-Mimicking Lure to Attract Females
Male swordtail characins, a type of tropical fish, have an alluring appendage that may redefine the idea of a dinner date. Just as fishermen use baits that look like food to attract fish, swordtail males have a flag-like sex ornament that looks appetizing to female fish.
"This is a natural example of a fishing lure designed to maximize the chance to catch a fish," said Niclas Kolm of Uppsala University. "In this case, it is not just any fish, however-it is a fish of the opposite sex that the lure is designed to catch."
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The fish mainly eat bugs, including ants, beetles, springtails, and fly larvae, which fall onto the water surface. In some populations, characins eat mostly ants, and lures work best if they mimic the foods that fish most often eat. For some characins in the study, that means males are waving pretend ants around in hopes of getting a bite.
The research team found considerable variation in the shape of sex organs among characins living in Trinidad, depending on what the fish are snacking on.
Evolution has essentially gifted the males with a fishing line and bait to attract passing females. Over the eons, the male charachins have developed a thin cord that extends from their gill area, on the end of which is an ornament of sorts. When a female bites onto this piece of flesh, she's in close-enough range and a good position for the male to do the deed, according to Scientific American.
The findings, reported in the journal Current Biology, lend support to the theory that sensory stimuli can encourage animals to diversify and eventually become separate species, reports The Daily Mail.
Over time, if an ant-shaped lure stops attracting females, the males would adapt. At the end of the day, females are going to choose the date that looks most like dinner.
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