THE HAGFISH.

Hauraki Plains Gazette, Volume XXXVI, Issue 489, 23 October 1925, Page 4

THE HAGFISH.

EQUIPPED WITH THREE HEARTS. BAFFLING SCIENTISTS. A primitive blind fish, having tmiee hearts, and a sense of smell controlled by some unknown kind of chemical guidance, is the Object of a series of baffling investigations .now being made by scientists. This fish, known as the hagfish, abounds in Monterey Bay, California, and is so voracious that net fishing in those waters has been rendered practically impossible. “Hagfishes alone among fishes are truly parasitic,” says Dr. David Starr Jordan, in “Fishes.” “They fasten themselves at the thrqat of large lushes and work their way into the muscle without tearing the skin, and finally inside, devour all the muscles of the fish, leaving the skin unbroken and the viscera untouched. These fishes become living hulks before they die.”

Physiologically, the hagfish is extremely interesting (say’s Science). Although it is blind, it hats rudimentary eye spots. These are not, however, sensitive to light. The skin of the adult is continuous over these eye spots, though the areas are characterised by the absence of skin pigment. The rudimentary and sightless eyes themselve isare embedded in pits in the cartilage of the skeleton of the head.

Although the hagflish is blind it is sensitive in two ways. When touched, however lightly, the head of the fish is drawn back to a distance of almost one-half the length, of the body, and the fish swims away. The hagfish has another sense which Jias its analogy in man and the other- mammals, that of smell. If a bit of food is dropped into an aquarium with a hagfish there is instant commotion. The blind fish swims in the general direction of the food, apparently guided by some chemical .’sense. Contact with odorous substances is facilitated by respiration.

The hagfish has three hearts. The eel's of the waters of the Atlantic seaboard. and Mississippi Valley have two —one being the regular organ, the other a contractile organ in/the tail. The hagfish has, in addition to the regular heart, a special heart for the portal system of veins. This heart has its own incoming and 'outgoing blood vessels, and all are well equipped with valves to ensure that the blood takes a one-way course. The third heart is in the tail, as in the cel. This, too, is a true pump, supplied with valves. It is double, but unlike the other two hearts its walls are not themselves able to contract. The power is therefore otherwise supplied 1 by a pair of straited muscles controlled by nerves. The other two hearts are not controlled by nerves.

There are still many facts of the biology and natural history of this peculiar and primitive fish to be determined. Living specimens are now kept in the Steinhart aquarium of the Golden Gate Park in San Francisco. Scientists have come to Cal|ifQrnia from distant parts of the world purposely to study the hagfiish, but even yet some of its habits are unknown. For example, we do not yet know where it spawns, nor when.