Female Fiddler Crabs Want Safety Over Sex: Study

When female fiddler crabs leave males behind during mating season, they aren’t just being picky—they are seeking shelter from predators, research shows.

AsianScientist (Sep. 6, 2016) – Research published in Royal Society Open Science has resolved a mystery over why female fiddler crabs visit and leave many males during mating season—the females were searching for a safe haven from birds and other predators, rather than hunting for a mate.

Fiddler crabs are found in mangroves and salt marshes and on sandy or muddy beaches of West Africa, the Western Atlantic, Eastern Pacific and Indo-Pacific. The male fiddler crab is known for having one claw that is considerably larger than the other.

Researchers from Australian National University used male-mimicking robotic crabs to test mate preferences in female crabs, as well as male reactions to the females. They also tested the females’ response to a simulated bird predator. From their studies, they observed that female fiddler crabs not seeking a mate visited successive males before settling in a new burrow in the same manner as mate-searching females.

“If a bird attacks, female fiddler crabs can move quickly and directly back to the last burrow it visited,” said Professor Patricia Backwell from the ANU Research School of Biology.

Backwell also said the findings overturn previous theories that the females were rejecting their male partners, helping scientists better understand the breeding habits of fiddler crabs, which are crucial to the ecological health of mangroves, salt marshes and muddy beaches around the world.

“This behavior of visiting and supposedly rejecting successive males has always been taken as a defining feature of female choosiness, but this study shows that things are not always what they seem.”



The article can be found at: Peso et al. (2016) Not What It Looks Like: Mate-searching Behavior, Mate Preferences and Clutch Production in Wandering and Territory-holding Female Fiddler Crabs.

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Source: Australia National University.
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