What is sham mating?
Sham mating is when animals display mating-like behaviour without reproduction occurring, meaning no fertilisation or egg-laying takes place. This can include behaviour such as courtship, mounting, or copulation-like actions that don’t result in offspring.
While sham mating has been most extensively studied in lampreys, research suggests that similar behaviors occur across a range of other marine species, with some octopus species observed engaging in same-sex mating interactions. According to scientists, this phenomenon may serve various social or evolutionary functions beyond reproduction.
Similarly, certain squid species, such as deep-sea squid, like Octopoteuthis deletron, have been found to exhibit same-sex mating behaviors, which researchers suspect could be linked to practice, dominance, or confusion due to limited visibility in their underwater environments.
In a 2011 study, scientists found evidence of bisexual behaviour among deep-sea squid with underwater footage showing that the squid will attempt to mate with any squid it encounters. According to the report, this mating strategy could be the result of limited vision in dark deep-sea waters, as the squid struggle to distinguish between potential mates and members of the same sex.
Although the precise reasons behind sham mating in these animals remain a mystery, these examples underscore the remarkable diversity and complexity of mating strategies in the natural world. Far from being anomalies, such behaviors may play important roles in social bonding, reproductive success, or simply navigating the challenges of life in the wild.
It’s a neat tactic used by female Siberian brook lamprey. Like most fish, lampreys reproduce by external fertilisation, with males and females releasing eggs and sperm into the water simultaneously.
Both sexes have multiple partners, and a male woos each chosen lady by wrapping his body around hers before releasing the goods. Yet the female is picky. She will go through the motions but hold onto her eggs until she finds Mr Right.
In a 2017 study by Hokkaido University, researchers observed that the nonparasitic lamprey Lethenteron kessleri often engages in repeated mating without releasing eggs in a behavior known as sham mating. This puzzling pattern suggests that females may be selectively evaluating potential mates while exhibiting promiscuous mating behavior.
In the study, it was found that each female mated an average of 77 times (ranging from 20 to 196 times), with sham mating occurring 65 percent of the time (ranging from 35 to 90 percent). Data showed that sham mating increased in larger groups of males, with sperm still being released, while the number of eggs released on each occasion declined.