The parasite may reach about 3mm long and 0.8mm wide.At the anterior or front end is the mouth (M) surrounded by the oral sucker (OS).In the middle of the worm is a large attachment sucker, the ventral sucker (VS).Behind this sucker are sex organs, the two testes (T), the ovary (O) and the two yolk or vitelline glands (V).There are many eggs (E) spread throughout the body.
- a marine snail
- another invertebrate
Derogenes varicus typically has a three host life-cycle and lives in
- a marine snail
- another invertebrate, then
- a fish, in which the adult develops
Known prey organisms
Based on studies in:
This list may not be complete but is based on published studies.
- Huxham M, Beany S, Raffaelli D (1996) Do parasites reduce the chances of triangulation in a real food web? Oikos 76:284300
Life History and Behavior
Cercariae are motile larvae with a tail which are produced asexually by the redia (see lifecycle).The cercariae are a type called cystophorous. The tail is used in at least three ways to assist the cercaria’s passage:
- it is enlarged and when swimming freely, the body of the cercaria is withdrawn within it
- the narrow posterior part of the tail is forked, and beats vigorously to keep the cercaria afloat
- when ingested by copepods or larvae of barnacles and crabs, the cercariae turn part of their tail inside out to produce a delivery tube which
- passes up into the predator’s gut and perforates the gut wall and,
- provides a tunnel for the body of the cercaria to pass along into the invertebrate’s body-cavity
- in the body-cavity the larva develops into a metacercaria -a stage where the larva grows, but does not usually become mature
- a spherical part which contains a coiled delivery tube and into which the body can be withdrawn
- an elongate forked swimming or flotation organ
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