MUSEMUM OF NATURE

Press, Volume CVII, Issue 31500, 14 October 1967, Page 22

MUSEMUM OF NATURE

Lamprey Has Lived For A Year Without Food

fContributed by the CUnterbury Museum.J

The Museum of Nature series of articles, devoted to subjects of topical museum and natural history interest began' a year ago. The introduction to the first article noted that, in many cases, the article would be amplified by a temporary exhibit at the museum. The subject of the first article—the lamprey—was the first of such temporary exhibits and it is about this strange animal we write again a year later. The particular lamprey in question was brought into the museum alive on Saturday, September 24, 1906, after it had been caught in a whitebait net at

the mouth of the Waimakariri River. It was a fine example, about 18in long, with bluegreen iridescence on its back fading to delicate pinks and cream on its throat and belly.

It wu an ideal subject for the first article and for the first of the new live displays. The preparators hurriedly constructed a makeshift tank and illumination. We were promised that the display case should be, redesigned as soon u . .. . well we felt sure that the lamprey was near the end of its days. But as many people know, the museum lamprey outlived all our predictions and the temporary exhibit Will be as permanent as the length of time the lamprey chooses to stay. Survivor The lamprey (a mature female) was, we felt, interest-

ing to the publie in that she is a survivor of a primitive group of vertebrates, progenitors of the true fishes. The label on her aquarium tank reads; "The lamprey is not a fish,” and this is because she lacks such major features as biting jaws and limb-like paired fins (that correspond to the arms and legs of man). Nevertheless, while the lamprey and hagfish are placed in a separate animal group on theft own, they are more like fish than anything else. Most textbooks on fishes do include them in their descriptions, and one author has preferred to broaden his definition of fish to include lampreys, so Stressing their close affinity to the rest of the piscine world. Going To Spawn When the lamprey waa first eaught she must have bora on her way up-river to spawn. Many miles upstream she would have found a suitable place for mating, neet-bulld-ing and eggdaying. After this, both she and her mate Would have died. This is the usual pattern with lampreys. Some Of the European lampreys cento to feed once they enter the river, living on their fat reserves until breeding has finished. We were unsure whether the Now Zealand lamprey would do the same. She waa offered fish, meat scraps, ox-liver. Ono Hve fish was placed in her tank. To all there was no response. In twelve and a half months captivity she has eaten nothing. "How doos she survive?", people ask. First, this lamprey does not look quite the same as she did a year ago. She is much shorter, thinner and her skin is rather wrinkled.

When she first arrived after he life in the sea, a period when she fed voraciously on the flesh of other fishes, she WU very sleek. Her flesh would have been saturated with reserve fat, enough to sustain her on her exhausting journey to the breeding grounds. Captured as she was at the very beginning of this migration, she had, as it ger at a lower level of activity.

The fat supplies in the tissues of various Russian lampreys hu been found to be regulated to the length of their migration upriver. One species Which travels 1200 kilometres up the river Amur has as much as 33 per cent of its body weight in fat. A species that travels 78 kilometres hu only .18 per cent of its body weight in fat fa a last resort the lamprey would have probably resorbed the eggs In ,hdr ovaries find thereby gained a rich nutritive food supply. And although she has foregone her chance to reproduce her kind, she hu, in confinement to the aquarium tank, outlived her normal life span by many months. Last autumn she lost the teeth from her rasping sucking mouth and it is probably that her whole gut hu disappeared. A smaller, drab, lamprey now has us wondering whether she will survive the hot Christchurch summer. Perhaps she is trying to outdo the only other published record of survival of a captive lamprey in New Zealand —that ofl7 months—and that lamprey wu still alive at the time the note was published.