On your next date, you might not want to try vomiting bioluminescent mucus, but for male crustaceans called ostracods it works like a charm. The female ostracods like it, say some researchers.
“When you’re there watching this display it’s spectacular. You can have up to nine species all in the same area displaying at similar times. I don’t know how the females do it, but they’re really good at figuring out who is their correct male,” explained Emily Ellis. She and Todd Oakley are scientists at the University of California, Santa Barbara who study ostracods in the Caribbean.
The bioluminescent mucus is vomited by the males in what looks like strings of beads that glow for a short while and then fade out. Some of the strings are in patterns, vertical streaks, or horizontal trails. At about the 30-second mark in the video below, there is a similar kind of bioluminescence.
The researchers say bioluminescent courtship is most likely a sexually selected trait, one which plays a role in choosing a mate. Vomiting glowing mucus doesn’t sound at all appealing to us, but it is a courtship display similar to what other species do like the bellowing of a male frog, of the flashing of fireflies.
Tens of thousands of ostracod species had been identified, but only the ones in the Caribbean are believed to be use bioluminescence for mating. Others use it as a defense against predators. Ostracods are small creatures typically ranging in size from 1 mm to 30 mm. Another name for this class of species is seed shrimp.
The researchers also found that the rates of species accumulation for a number of species which used bioluminescence in courtship was higher than in those that did not experience courtship. Accumulation is the rate of new species that emerge.