Bopyridae
![Shrimp displaying bulge indicating bopyrid parasitism](/Images/godic/202501/01/Lebbeus_grandimanus_from_North_East_Pacific,_with_unidentified_bopyrid_-_journal.pone.0035350.g001-C4244.png")
The Bopyridae are a family of isopod crustaceans in the suborder Cymothoida. Members of the family are ectoparasites of crabs and shrimps. They live in the gill cavities or under the carapace where they cause a noticeable swelling. Fossil crustaceans have occasionally been observed to have a similar characteristic bulge.