Pom Pom Crabs
These crabs are also called as the Boxer crabs or the Cheer leaders of the deep sea. The reason behind these names are the sea-anemones that these crabs carry in each of their claws, making them look like the cheer leaders with pom poms in their claws.
The scientific name of these crabs is Lybia leptochelis ( and also few other species of family Lybia). They are very small in size, around 13 mm to maximum 2.5 cm. Unlike the robust claws of major other crab species, the claws of these crabs are delicate and small, like a pair of tweezers. The carapace of these crustaceans exhibits a typical polygonal mosaic like pattern in pink, brown and yellow colours. The legs show dark purple bands. it is difficult to detect this small, colorful crab in its surroundings.
The pom pom crabs are commonly found in the shallow parts of Indian and Pacific oceans as well as in the Red Sea of Israel. Similar crabs found in the Hawaiian Islands are known by the name Kumimi Pua or the ‘inedible flower crab’.
The dance of the Pom Pom Crabs. Source: Here
This crab and anemone relationship is a mutually beneficial relationship. The crabs use the stinging anemones to protect themselves from the predators and the anemones get scraps of food. Also, the anemones are stimulated into asexual reproduction by the crabs.
Several studies have been carried out over the years to determine the behaviour of these crabs. It has been observed that if a pom pom crab lacks anemones, then it tries to steal it from other and even fights bitterly for it. Then each of the crab tears its single anemone into two, forming identical clones. They attache the anemone to their claws with delicate hooks.
The Pom Pom Crabs fighting for the Anemones. Source Here
Laboratory studies have found that if one of the anemone is removed carefully with the help of tweezers, then the crab tears the remaining anemone into two equal fragments and each fragment then regenerates into original sized anemone. This is a first of its type of one animal stimulating another animal to reproduce asexually. When the DNA of these fragments were checked, they were found to be identical – proving that the anemones were clones
Studies have found that these anemones are of the genus Alicia. Crabs defend themselves by waving their anemones which have cnidocytes or stinging cells. But how or from where do the crabs acquire these anemones is not known till date. These anemones are never found in free living conditions. The pom pom crabs are born as free floating larvae, later they develop into adults. But each and every adult is always found with these anemones in their claws. So this is a symbiotic relationship and the anemones depend on the crabs.