How Climate Change Is Confusing the Social Life of Fiddler Crabs

Rising sea levels are affecting coastal species in many different ways.

Rising sea levels are pushing different species of fiddler crabs together, and their interactions may cost one species vital territory.

Most fiddler crab species share similar lifestyles, but each has its own very particular tolerances for how long, how often, and how much its burrow floods during high tide. In the intertidal zone, a few centimeters can make a big difference, so each species sticks to a very narrow strip of habitat. Along the coast of Darwin Harbour in northern Australia, rising sea levels are sending two fiddler crab species, elegant fiddler crabs (Tubuca elegans) and signaling fiddler crabs (Tubuca signata), scurrying higher to seek less waterlogged homes.

The problem is, they’re moving into the habitat already occupied by the banana fiddler crab (Austruca mjoebergi), which is having trouble adjusting to its new neighbors—mostly because it’s being too friendly, according to a new study.

Male fiddler crabs of all species stake out a territory, dig a burrow, and defend it against intruders.

Photo: Thomas Brown/Wikimedia Commons (CC BY 2.0)

To view the Creative Commons license for the image, click here.

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