Lampreys Look for Love by Spraying Pheromone-Laced Semen

The image depicts a sexually mature male sea lamprey, characterized with a dorsal ridge, in a typical gravel patch where sea lampreys build nests and release pheromones that signal to ovulating females the presence of spawning aggregations. (Anne M. Scott)

(CN) – Oceans and rivers play host to a plethora of mating creatures in a ballet of breeding and scientists in a newly published study say the jawless, eel-like male lamprey can entice single females with a love pheromone.

It is not as romantic as it may sound.

Male lampreys produce an aphrodisiac pheromone from their semen called spermine, according to a study published Tuesday in the scientific journal PLOS Biology.

Lampreys migrate from saltwater to freshwater to breed. Some species are parasitic and affix their rows of teeth into their prey to suck blood.

Like some mating birds, male sea lampreys gather and compete with other males to attract females. However, unlike the colorful birds-of-paradise that lure their mates with vibrant plumage and dance, lampreys ejaculate into the water.

Each male builds its own nest and releases the sex pheromone from its gills. Males defend their nests, and females move from nest to nest to spawn intermittently for about a week before the mature adults die.

The male’s spermine does not attract other male lampreys or pre-ovulating lampreys to their nests. Researchers say the pheromone stimulates the lamprey olfactory system and attracts females who are ready to mate.

Researchers studied immature adult sea lampreys captured in tributaries of the Laurentian Great Lakes by the U.S. Fish and Wildlife Service and Fisheries and Oceans Canada. The creatures were allowed to mature in a Michigan river until they were ready to mate.

The lampreys showed the pheromone was potent in attracting ovulating females.

“This discovery implicates a new strategy that male animals use to recruit mates through the release of chemical cues in semen,” Michigan State University researcher Anne M. Scott said. “Ovulatory females likely use spermine released along with sperm as a reliable signal for the presence of actively spawning males in the vicinity.”

Scott was joined in the research by scientists from Shanghai Ocean University. The study was funded by the Great Lakes Fishery Commission and Shanghai Ocean University.

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