Dactylogyrus vastator Nybelin, 1924. Dactylogyrusis the largest helminth genus with more than 900 species. They live mostly on the gills of cypriniform fishes.
OTHER COMMON NAMES
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.
Widespread in Palearctic region on common carp (Cyprinus carpio), Crucian carp (Carassius carassius), and goldfish (Carassius auratus).
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.
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.
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. ♦
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