No common name

Gyrodactylus pungitii

ORDER

Monopisthocotylea

FAMILY Gyrodactylidae

TAXONOMY

Gyrodactylus pungitii Malmberg, 1964. About 400 species attributed to Gyrodactylus. Morphologial and anatomical differences between the many species of Gyrodactylus are relatively small, making their taxonomy difficult.

OTHER COMMON NAMES

None known.

PHYSICAL CHARACTERISTICS

Length 0.023-0.03 in (0.6-0.9 mm). May contain developing embryo. Haptor fan-shaped with one pair of hamuli linked by two bars; sixteen hooklets arranged around periphery. Single pair of eversible adhesive sacs on head. No eyespots. Vitellarium absent or possibly reduced. Germarium reduced. Single testis; penis armed with hooks. Penis absent in young specimens.

DISTRIBUTION

Not systematically mapped, but likely to occur wherever Pungi-tius pungitius, its specific host, occurs.

HABITAT

Skin, fins (pharynx) of stickleback, Pungitius pungitius.

Medical Underdeveloped Reproductive

BEHAVIOR

Gyrodactylids rely on hamuli and hooklets for attachment. They move like leeches.

FEEDING ECOLOGY AND DIET Feeds on fishes' epidermis.

REPRODUCTIVE BIOLOGY

Unique among monogeneans. New hosts usually infected by transfer of parasites when hosts make contact with one another. Population growth of many gyrodactylids is limited by host reaction. Mechanism of limitation largely unknown as of 2003.

CONSERVATION STATUS Not threatened.

SIGNIFICANCE TO HUMANS

None known for G. pungitius. There are, however, strains of Norwegian salmon (Salmo salar) unable to control population growth of G. salaris. Young salmon (salmon parr), rarely exceeding 6 in (15 cm) in length, may support more than 10,000 parasites. The parasites' heavy grazing on the fishes' outer layer of skin, both in farms and in the wild, leads to loss of osmotic integrity, invasion by secondary disease agents, and death. Parasite probably introduced to Norway by Baltic salmon that have some resistance to it. ♦

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