Sacculina
| Sacculina | |
|---|---|
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| Sacculina carcini (highlighted) attached to a female Liocarcinus holsatus | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Subphylum: | Crustacea |
| Class: | Maxillopoda |
| Order: | Cirripedia |
| Family: | Sacculinidae |
| Genus: |
Sacculina Thompson, 1836 |
| Type species | |
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Sacculina carcini Thompson, 1836 |
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Sacculina is a genus of barnacles that is a parasitic castrator of crabs. They belong to a group called Rhizocephala. The adults bear no resemblance to the barnacles that cover ships and piers; they are recognised as barnacles because their larval forms are like other members of the barnacle class Cirripedia. Depending on the location, the prevalence of this unusual crustacean parasite in its crab host can be as high as 50%. They are a part of a group of infamous species that are body snatching parasites that infect crustaceans and crayfish.
They live in a marine environment. During the span of their larval stage they are pelagic but as they form into an adult they live as an adult in crabs. They primarily host the green crab which is native to the Eastern Atlantic Ocean. Though these crabs have spread to other bodies of waters, it isn't believed Sacculina has migrated along with them to these places too.
The body of this adult parasite can be divided into two parts: one part is called the "externa" where a bulbous reproductive organ of the parasite sticks out of the abdomen of the host. Then the other part is called the "interna" which is inside the host's body. This part is composed of root like dendrils that wrap themselves around the host's organs which gives its group name already known as Rhizocephala meaning "root-head". Through microCT scans, these roots have been discovered to wrap around certain organs of the body with most around the hepatopancreas which is found in crustaceans. This area is primarily for sucking up nutrients which would understandable why most concentrate in that region. In a similar species called Briarosaccus roots were seen extending to the brain and central nervous system which could help explain how parasites like these can manipulate their hosts behavior.
The female Sacculina larva finds a crab and walks on it until it finds a joint. It then molts into a form called a kentrogon, which injects its soft body into the crab while its shell falls off. The Sacculina grows in the crab, emerging as a sac, known as an externa, on the underside of the crab's rear thorax, where the crab's eggs would be incubated.
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Wikipedia