Male blue-lined octopuses paralyze females before mating to prevent being eaten
A team of neurologists, environmentalists and bioengineers at the University of Queensland, in Australia, has found that male blue-lined octopuses paralyze females prior to mating to avoid being eaten. In their study in the journal Current Biology, the group captured several octopus samples and studied their behavior and vital signs as they mated.
Prior research has shown that some male octopuses have evolved a means to prevent being eaten by females when mating; one species, for example, has developed a sperm transfer arm to allow itself some distance during intercourse. In this new study, the research team focused their efforts on blue-lined octopuses. Female blue-lined octopuses are much larger than the males and have been known to eat their partners after copulation.
The researchers captured several male and female specimens and observed them during mating. They found that the males bit the females in a way that slightly punctured the aorta, allowing entry of a small amount of poison.
The poison, tetrodotoxin, the same poison used by pufferfish, paralyzed the female while the male copulated with her. His efforts continued until the female began to recover. The poison used by the male was made by bacteria that lived in its body.
Monitoring of their vital signs during copulation showed that the female stopped breathing altogether after eight minutes—not long enough to kill her, but long enough to be mounted. Her skin color also paled noticeably and her pupils constricted; all of the females tested were unable to respond to bright flashes of light or other stimuli. In short, all nerve control was lost.
The researchers found that envenomating the females rendered them completely immobile and therefore unable to participate in copulation, and more importantly, to the male, unable to cause him harm afterward.
After mating, all females lived to lay their eggs three to 29 days later, though they all showed evidence of the bite, such as bumps and wounds.
More information: Wen-Sung Chung et al, Blue-lined octopus Hapalochlaena fasciata males envenomate females to facilitate copulation, Current Biology (2025).
Journal information: Current Biology
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