(No common name)

ORDER

Monopisthocotylea

FAMILY

Dactylogyridae

TAXONOMY

Dactylogyrus vastator Nybelin, 1924. Dactylogyrus is the largest helminth genus with more than 900 species. They live mostly on the gills of cypriniform fishes.

OTHER COMMON NAMES

None known.

PHYSICAL CHARACTERISTICS

About .045 in (1.25 mm) long. Two pairs of hamuli, with ventral hamuli reduced to spicules. One or two supporting bars. Fourteen hooklets, each with an enlarged handle. Three pairs of eversible adhesive sacs. Four eyespots. Male copulatory organ has hardened penis tube with accessory sclerite. Single testis.

DISTRIBUTION

Widespread in Palearctic region on common carp (Cyprinus carpio), Crucian carp (Carassius carassius), and goldfish (Carassius auratus).

HABITAT

Haptor lodges between two secondary gill lamellae.

BEHAVIOR

Little is known about behavior. Parasite secures itself to host principally by dorsal hamuli.

FEEDING ECOLOGY AND DIET

Feeds on gill epithelium.

REPRODUCTIVE BIOLOGY

Ovoid eggs are washed out of host's gill cavity and sink to bottom. Ciliated oncomiracidium emerges in 3–5 days, depending on water temperature. Larvae drawn into gill cavity by current attach themselves to host's gills. Some larvae may first attach to host's skin and then migrate to gills. Eggs are thought to spend the winter in a state of diapause, or period of inactivity.

CONSERVATION STATUS

Not threatened.

SIGNIFICANCE TO HUMANS

Causes mass mortality among fingerling carp in fish-rearing ponds. Abnormal multiplication of cells in the gill epithelium interferes with carp's respiratory function. Parasite is especially significant in the former Soviet Union and eastern and northern Europe where carp are bred for food.