Clinostomum marginatum

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Clinostomum marginatum
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Platyhelminthes
Class:	Trematoda
Order:	Diplostomida
Family:	Clinostomidae
Genus:	Clinostomum
Species:	C. marginatum
Binomial name
Clinostomum marginatum (Rudolphi, 1819)

Clinostomum marginatum is a species of parasitic fluke (class Trematoda).^[1] It is commonly called the "Yellow grub". It is found in many freshwater fish in North America, and no fish so far is immune to this parasite. It is also found in frogs. Clinostomum marginatum can also be found in the mouth of aquatic birds such as herons and egrets. They are commonly present in the esophagus of fish-eating birds and reptiles. Eggs of these trematodes are shed in the feces of aquatic birds and released into water. Aquatic birds become hosts of this parasite by ingesting infected freshwater fish. The metacercariae are found right beneath the skin or in the muscles of host fish.

The life cycle of the fluke consists of two intermediate hosts and one definitive host. The parasite's eggs hatch in the water and the miracidium invades the foot of a snail. The cercaria leaves the snail and encysts in the muscle of the connective tissue of fresh-water fish species or in the muscle of frogs. The metacercarial stage is that is formed is then referred to as the “yellow grub”. The encysted metacercariae appear yellow, with a slightly oval-shaped spot, and are about 3 to 6 mm long. Metacercariae are common in the caudal, dorsal, and pectoral fins; on the inside surface of the operculum, and in the flesh. The adult trematode is found in the mouth and esophagus of herons and other fish-eating birds.