Profilicollis is a genus of acanthocephalan parasites that are found in crustaceans and shorebirds. Profilicollis parasites use decapod crustaceans as intermediate hosts and species of shorebirds as definitive hosts.

The parasite first develops in mole crabs of North and South America. After it infects a mole crab, it becomes dormant until the crab is eaten by a suitable bird, such as a Surf scoter or Herring Gull. Once the parasite has passed through the stomach of the bird, it develops into an adult worm and attaches to the intestines of the bird. Eggs produced by the parasite are released through feces of the bird and enter the ocean. In the ocean, they are transported by ocean currents until they are ingested by a filter-feeding mole crab.

The species Profilicollis altmani has become the subject of increasing research as it has been found to be contributing to a substantial number of deaths of the southern sea otter: Enhydra lutris nereis. Between 1998 and 2001, upwards of 16 percent of sea otter carcasses found around central California the cause of death was determined to be a direct result of acanthocephalan peritonitis, caused by this species of parasite. Most of the sea otters that were found to be killed by infections by Profilicollis altmani were either young juvenile or older female otters, and it is hypothesized that they feed on sand crabs because they are less skilled at foraging or because of a decrease in their preferred prey.

There are several species of Profilicollis, including: P. altmani, P. antarcticus, P. botulus, P. bullocki, P. formosus, P. major, P. novaezelandensis, and P. sphaerocephalus.

Image Caption: Acanthocephalan parasite, Profilicollis altmani from the mole crab, Emerita analoga. Credit: T. Goulding/Wikipedia (CC BY-SA 3.0)