Cod worm

Phocanema decipiens

ORDER

Ascaridida

FAMILY

Anisakidae

TAXONOMY

Ascaris's decipens (Krabbe, 1878), originally Cristophora cristata, Greenland coast. Latest name: Pseudoterranova decipens.

OTHER COMMON NAMES English: Seal worm.

PHYSICAL CHARACTERISTICS

Often found in cod, but are also found in many other species of fish. In the larval stage, they are 0.20-2.28 in (5-58 mm) in length by 0.012-0.047 in (0.3-1.2 mm) in width, and yellowish, reddish, or brownish in color. They have well-developed and distinct lips. The excretory system is elongated and cord-like, while the adult esophagus is cylindrical in shape.

DISTRIBUTION

Located in the Atlantic Ocean. (Specific distribution map not available.)

HABITAT

Found in the guts or flesh of fish such as cod. In their final hosts, they are found mostly in gray seals and other similar animals.

BEHAVIOR

When inside fish, they are usually found tightly coiled in the flesh and guts of fish. They are often found in considerable numbers, particularly in the belly flaps of fish, where they can remain for extended periods of time encased in a sack-like membrane produced by the fish tissue. Adults also live in the stomach of gray seals and other similar creatures. Eggs of the parasite pass into the waters with the mammal's excreta, and when the eggs hatch, the microscopic larvae must invade a new host in order to develop. Small shrimp-like crustaceans, eu-phausiids (often called krill), and other parasitic crustaceans eat the larval worms. When a fish eats these infested crustaceans, the larval worms are released into its stomach. They then bore through the stomach wall and eventually become encased in the guts or in the flesh of the host fish. The lifecycle is completed when a suitable marine mammal eats an infested fish. The incidence of infection in fish generally increases with length, weight, and age of the fish host.

FEEDING ECOLOGY AND DIET

As a parasitic species, they live off of nutrients of their hosts, primarily from the guts and tissues of fishes.

REPRODUCTIVE BIOLOGY

Females have ovaries and uteri, while males have copulatory spicules.

CONSERVATION STATUS

Not listed by the IUCN.

SIGNIFICANCE TO HUMANS

The cause of human illness in countries where there is ingestion of raw or lightly cured fish. The disease is called anisakia-sis and can be easily prevented because larvae are killed in only one minute at a temperature of 140°F (60°C) or higher. In the wrong host the worms get the wrong signal and migrate through the tissues of its host, causing hemmoraging and bacterial infections. This kind of migration is known as "visceral larval migranes." ♦

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