How boxer crabs acquire their gloves

Jan. 31 (UPI) -- Boxer crabs are called so because they carry around sea anemones, one in each claw. The accessories look like a pair of gloves or pompoms.

Boxer crabs have been studied sporadically over the last several decades, but until now, scientists hadn't figured out how the tiny crabs acquire their gloves.

Recently, when researchers from Bar-Ilan University in Israel tried and failed to find "free living" examples of sea anemones belonging to the genus Alicia -- the boxing crab's gloves of choice -- they decided to set up a series of lab experiments.

In the lab, researchers deprived captured boxer crabs of their gloves. Crabs who lost one glove, split their remaining anemone in half. The split anemone regenerated into two clones within a few days.

Crabs robbed of both gloves sought out other crabs to wrestle and steal an anemone. Almost all encounters ended in a successful theft. After the battle, each crab splits their lone anemone into two clones.

Genetic analysis of gloves taken from crabs in the wild revealed most anemones held by boxer crabs are clones, which suggests most crabs attain their gloves in the wild the same way the did in the lab.

Researchers shared the results of their experiments in the journal PeerJ.

There are ten species of boxer or boxing crabs, all belonging to the Lybia. The anemones serve as a defense mechanism for the tiny crabs, and being carried around by the crabs offer anemones a chance to absorb more food particles. Some boxer crabs have been observed substituting sponges and corals for anemones.