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Relative, Robber, Resource
| Article
# : |
19798 |
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Section : |
NATURAL SCIENCE
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| Issue
Date : |
3 / 1991 |
2,236 Words |
| Author
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Frederic Martini
Frederic Martini has been teaching at the Shoals Marine
Laboratory, Appledore Island, Maine, since 1971. For the last
four years he has been involved in a detailed study of an
isolated hagfish population in the Gulf of Maine. |
With a rush of draining water, the garbage can swings over the stern of the research vessel John M. Kingsbury. As it hits the deck, a mass exodus begins; from holes around the equator of the can, wriggling bodies slip and slide to the deck. They are shocking pink, sinuous, and bent on escape. Everyone lunges after them; in moments thick masses of slime cover hands, drip from arms, and carpet the rolling deck. The escapees are hagfish, which were live-trapped on the bottom of the Gulf of Maine at a depth of 400 feet.
Hagfish are often called slime eels, but they are only distantly related to eels or any other true fish. The characteristics of the Atlantic hagfish, Myxine glutinosa, are representative of the roughly 45 other hagfish species. They are not unusually large (Myxine average 16 inches in length and weigh around four ounces), but most of their other characteristics are radically different from those of true fish, such as the eel or salmon. For example, a true eel has a cranium, vertebrae, paired fins, gill arches, jaws and a sensory array that includes eyes, three semicircular canals in the inner ear, and a complex lateral line (a vibration-detection system). Hagfish possess a partial cranium, but no traces of vertebrae, paired fins, or jaws; the gills are in pouches rather than arches. They are without eyes, have a single semicircular canal, and show only hints of what might once have been a lateral line.
Hagfish have many unique anatomical and physiological specializations. For example, although hagfish lack jaws, they have a set of opposing tooth plates that can open and close like a book. The array of stiff yet flexible teeth can seize and tear soft tissues quite effectively. Whether this structure represents a muscular tongue or a lower jaw that folds in the middle has yet to be determined. Hagfish have a fairly typical heart, but they also have six "accessory hearts," including one in the tail and another in the liver, that assist in maintaining blood pressure and flow.
A bucket of ooze
The name slime eel acknowledges a third striking specialization: Along each side of the body are roughly 120 glands that can secrete a viscous protein-carbohydrate complex. When released into the water, the molecules unfold and absorb water, forming a gelatinous mass of slime. A single hagfish can within moments convert a five-gallon bucket of water into a transparent ball of ooze.
Hagfish caught on this expedition are headed for the
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