Aspidogaster conchicola von Baer, 1826, Anodonta, Unio Prussia.
PHYSICAL CHARACTERISTICS Adults are about 0.08 in (2.5-2.7 mm) long and 0.04 in (1.1-1.2 mm) wide, with a large sucker that covers almost the entire ventral surface of the organism. The body narrows to a neck-like region with a mouth at the front tip. The large ventral sucker has a windowpane pattern of sucking grooves. A lone testis is located in the middle of the posterior half of the body, and the ovary sits in the center and to one side of the animal. A common genital pore opens anteriorly about a quarter of the body length behind the mouth sucker.
Europe, North America, China, and Egypt. HABITAT
Hosts are snails, including Viviparus malleatus and Goniobasis livescens; and such mussels as Anadonta grandis. Aspidogaster species use only one host. Sometimes, other species, like turtles, will eat infected mussels. The flukes can survive temporarily in the turtle's stomach.
Aspidogaster larvae use snails and mollusks as their hosts. Larvae apparently infect the host mollusk by entering its siphon. Various reports indicate that the flatworms enter the host either as larvae or as eggs containing larvae. Aspidogaster eggs hatch after they are eaten by freshwater snails or mussels. Eggs that are not eaten can survive for about two weeks. In snails, the newly hatched worms lack cilia and move about by creeping. The larvae migrate to the snail's intestines and then to the hepatopan-creas, where they mature and lay eggs.
FEEDING ECOLOGY AND DIET
Parasites feed on host epithelium and mucus using the an-teriroly located mouth.
The entire life cycle of Aspidogaster from egg to adult to production of the next generation of eggs takes about 270 days at 68°F (20°C). Unlike digenetic trematodes, the life cycle of this species and other members of the subclass Aspidogastrea occurs in just one host and does not involve asexual reproduction. The eggs are oblong, operculate (having a small covering structure), and about 0.005 in (128-130 pm) long and 0.0019 in (48-50 pm) wide. Juveniles, which have a shape similar to the adults, grow from about 0.02 in (0.5 mm) in length to 0.05-0.06 in (1.25-1.5 mm).
Not listed by IUCN.
SIGNIFICANCE TO HUMANS None known. ♦
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