Startling male crabs carrying eggs and the strange 'transition' process

Male blue crabs lose their reproductive function and develop ovarian tissue due to a notoriously cruel parasite.

Crabs infected with the parasite Sacculina carcini.

Sacculina carcini is known as one of the cruelest 'transgender doctors' in the animal world.

Sacculina carcini is a cruel parasite that attacks crabs , especially green crabs in Europe. After attaching to the crab's bottom hair membrane, their larvae inject vermigon into the crab's blood, developing into parasites. These parasites not only suck nutrients from the crab but also attach to the nervous system to control the crab's behavior.

They cause major physiological changes, including changing the sex of male crabs to female crabs. Infected crabs cannot molt, male crabs lose their reproductive organs and develop ovarian tissue .

The parasite lays its eggs in a sac attached to the crab's abdomen, and the male crab is controlled to protect and care for the parasitic eggs like the mother crab. This poses a serious risk to the crab supply, negatively affecting humans.