Trematode Metacercariae of Sea Urchins


Category 3 (Host Not in Canada)

Common, generally accepted names of the organism or disease agent

Metacercarial infection of sea urchins.

Scientific name or taxonomic affiliation

Various species in the Digenea families Fellodistomidae (including Proctoeces maculatus a known pathogen of mussels), Lepocreadiidae and Zoogonidae.

Geographic distribution

Specific reports from Japan, the Mediterranean Sea, the vacinity of Woods Hole, USA and the Atlantic coast of France. However, the distribution is probably global, although each species may be confined to certain locations. None have been reported from Canada.

Host species

Psammechinus microtuberculatus, Psammechinus miliaris, Sphaerechinus granularis, Psammechinus miliaris, Anthocidaris crassispina, Diadema setosum, Hemicentrotus pulcherrimus, Strongylocentrotus intermedius, Strongylocentrotus purpuratus, Paracentrotus lividus, Arbacia lixula, and Arbacia punctulata as well as various other sea urchins and bivalves.

Impact on the host

Most metacercaria are encysted in the gonads, muscles of Aristotle's lantern, or in the ampullae of the tube feet. Majority of species are innocuous. However, when heavily infected, the jaw muscles of Aristotle's lantern become less functional and may affect echinoid feeding.

Diagnostic techniques

Squash Preparations: Thin slices (about 3 mm thick) of the sea urchin gonad, muscles dissected from Aristotle's lantern, and tube feet excised from the body surface pressed between two plexiglass plates and examined under a dissecting microscope (50 ×) show metacercariae.

Histology: Cross sections of metacercariae can be observed within the tissues. However, fixed tissues must be decalcified prior to processing for histological examination.

Methods of control

Prevention and control impractical.


Jangoux, M. 1987. Diseases of Echinodermata. 2. Agents metazoans (Mesozoa to Bryozoa). Diseases of Aquatic Organisms 2: 205-234.

Stunkard, H.W. 1941. Specificity and host-relationships in the trematode genus Zoögonus. The Biological Bulletin (Woods Hole, Mass.) 81: 205-214.

Citation Information

Bower, S.M. (1996): Synopsis of Infectious Diseases and Parasites of Commercially Exploited Shellfish: Trematode Metacercariae of Sea Urchins.

Date last revised: September 1996
Comments to Susan Bower

Date modified: