NATURE NOTES

New Zealand Herald, Volume LXX, Issue 21450, 25 March 1933, Page 1 (Supplement)

NATURE NOTES

LAMPREYS' HABITS

Br J. DBUMJIOND, F.L.S., F.Z.S

In a letter on lampreys caught in a creek at Takanga, Hick's Bay, north of Gisborne, " J.G.W." asks: " What is the hole for on tojj of the head?" The hole is a single nostril, leading into a small blind bag. The nostril is not the most conspicuous equipment of a lamprey, but it is unique and is worth inquiring into and explaining. This correspondent passes on to lampreys' strange sucking mouths, with rows of recurved teeth, and he asks what lampreys live on. Another correspondent writes from Palmerston South: " Two years ago I caught two lampreys in the Shag ltiver. I saw two others clinging to stones. More than forty years ago, when I caught some in the Shag River, I asked my mother what they were. She replied that they were horse-leeches, and said that they were common in brooks in Scotland."

New Zealand shares the possession of lampreys with almost all the rest of the world. The fate of an early English king, who waa a worthy son of William the Conqueror and a valiant warrior, but who died ingloriously of a surfeit of lampreys, is sufficient evidence that they are palatable. They were in high esteem in Rome's gluttonous and luxurious days, Roman citizens spending large suras of money and much care in keeping them for the table. Down to the Middle Ages, lampreys were in favour in civilised countries, especially among the great, but the taste for them declined, lamprey-fisher-ies were discontinued, and now the lamprey has less standing than almost any other edible creature of the sea. In New Zealand Maoris ranked it with eels, do so now, in fact, but never went to particular trouble to take it.

A lamprey's flesh may be delicate. Its habits are repugnant. A shark, rushing at its prey, tears and rips it, and kills it outright. A lamprey is a blood-thirsty parasite. It strikes its suctorial mouth against a fish. In an instant, according to Dr. Starr Jordan, it is attached so firmly that the victim seldom rids itself of its persecutor. Using horny teeth on its muscular protrusible tongue, which works like a piston, it rasps off the flesh and sucks the blood, making a horrible meal until the fish dies.

A lamprey attached to a fish caught in a net usually lets go and escapes through the meshes. If it clings to the fish and is brought ashore, it hangs on like a bulldog as long as the fish is in the water. Its practice is to drop as soon as it i 3 exposed to the air, 'but this is not always done. Even in the open air it may retain its hold for a time. Tests have disclosed amazing strength in a sucker. Lampreys allowed fco attach themselves to a person's arm or hand could not be detached until they were lifted from the water. A lamprey, while feeding, has free trips to any part of the sea its host visits. With its sucking mouth it anchors itself to stones in the water, holds itself against a strong current, climbs over waterfalls, carries stones and builds its nest in the form of a groove on the bed of a creek or river.

These "stunts" gave it its popular name, which is from lambere, to lick, and petra, a stone. Its class, occupied by itself and by the hagfish, is the Cyclostomata, which means round mouth. The mouth contains many teeth, arranged in rows. These teeth are sharply pointed, and are very strong. Below the centre of the mouth there is a circular opening. This contains the flattened tongue, armed with finer teeth than the teeth in the mouth, arranged in two curved rows. A circle of soft membrane surrounds the mouth, and this circle, in its turn, is surrounded by a small fringe.

Lampreys' habits have not been recorded extensively in New Zealand. Although the New Zealand species is different from species in the Old Country, a description by an English writer of their nesting methods may be accepted as typical. This writer 6tates: "Having arrived at a shoal that seems to present suitable conditions for a spawning-nest, a beginning is made by a single individual, or by a pair, to move stones with the mouth from the centre to the margin of an area one or two feet in diameter. Many stones are placed in this way, especially at the upper edge. They are cleaned free of sediment and of seaweed, by being moved and by being fanned with the tail. "When the proper condition of sand is found at the bottom of the basin formed, it is ready to bo used as a spawning-nest. Many nests are begun and abandoned. The reason is a mystery. It may be because the lampreys do not find the requisite conditions to supply all their needs and fulfil all conditions for ideal sites." Young lampreys, called pride and niners, or nine-eyes, in the Old Country, are slender, wormlike, toothless and eyeless. They are hatched ten or fifteen days after the eggs are fertilised. They stay in the nests for about thirty days. In England they then wander down the stream. Having selected a suitable place, they burrow in the sand or mud. For three or four years they are absolutely blind, and feed on minute organisms or on organic matter in the mud.

New Zealand seems to have only one species of lamprey, Geotria australis, ,the Maoris' korokoro. The Dominion hag one species of hagfish, known to tho Maoris as tuere. This creature is more singular even than the lamprey. Its tongue is powerful. Instead of adhering to a fish attacked, it simply bores in and devours all the muscular parts without breaking the skin, leaving tho fish a living hulk of head, skin and bones. A hagfisli's appetite is insatiable. A single individual of a Chilean species kept in captivity devoured eighteen times its own weight of fish-flesh in seven hours. Hagfislies are regarded as degenerate lampreys. Both have eel-like bodies, and both have the same anatomical features, but the hagfish's mouth is different from the lamprey'B, serving a different purpose.

Now Zealand's small aquatic plants belonging to a group known popularly as bladderworts, and to botanists as Utricularia, are famous for tho ingenious traps they set in the water to catch very small aquatic creatures. Professor It. Matheson, Cornell University, has stated that bladderworts should be considered as a possible agent in controlling and cheeking mosquitoes. Although little is known about the cultivation' of bladderworts, Professor Matheson points out that they are graceful plants, grow luxuriantly wherever they occur, and should be additional attractions in fishponds, small lakes, and pools of water. The creatures which they entrap, and which, strange as it may seem, they use for food, are mostly small organisms belonging to tho crustaceans, protozoa and allied groups, but it is reasonable to believe that at least some mosquito grubs are on :fche bladderworts' menu..