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- Title
FURTHER AQUARIUM OBSERVATIONS ON THE SPAWNING HABITS OF THE RIVER LAMPREY (PETROMYZON FLUVIATILIS).
- Authors
Hagelin, Lars-Olof
- Abstract
The following observations on details of the spawning habits of the river lampreys have been made: 1. The external sexual characters of the river lampreys appear about two weeks before spawning. 2. According to the author the river lamprey probably performs two different types of stone-moving: a) When the male lifts a stone from the bottom with his buccal disk the anterior part of the abdomen serves as a support against the bottom. In moving the stone upwards vertically through the water the male turns himself on his side and his tail performs rapid and powerful swimming movements (three per second) during which the side of his body glides in a bow along the bottom and rests against it (Fig. 1). When the body of the male has a vertical posture without the slightest contact with the bottom he usually drops the stone. Probably this type of stone-moving is a behaviour of incomplete nest building at low intensity. b) The second type is the usual one in the nest building. Here without any difficulty the male moves with his oral disk small pebbles by slow sidewise swimming movements of his tail. If the male wishes to move a larger stone (diameter 2–4 cm), jammed in between the pebbles of the bottom material, his tail performs the same sidewise swimming movements but now with a higher frequency (five to six per second) during which sand and pebbles are stirred up. 3. In the film tank when the male works persistently in the nest the female swims in small circles passing over the nest each round. Every time she passes over the pit the female sinks down in such a manner that the posterior part of her abdomen glides over the head of the male. Every circle performed by the female takes about five to six seconds. 4. The male performs a gliding movement with his oral disk along either side of the body of the female. This action may be interpreted as a courting activity made by the male and as an introduction to the breeding act. The courting act starts on a level with the anterior dorsal fin of the female and then the male glides anteriorly to the branchiae (Fig. 3). From this position his oral disk glides up to the back of the female and forwards to the anterior part of her head where the male attaches himself. 5. Often before a spawning act the male attached to a stone outside the nest performs some convulsive curving movements (Fig. 6) with his tail then showing the same characteristic loop typical of every spawning act. 6. As a rule in the spawning act the backward bending of the body of the female results in an erection of the fore part of her body while the region round and behind the urogenital opening rests on and is partly pressed into the gravel during the vigorous flapping movements of her tail. 7. The pictures of the film, the short dimensions of the papilla (6 mm) of the male and the large distance (2–2½ cm) between the hindmost position of his wound tail and the urogenital opening of the female provide clear evidence that the fertilization of river lampreys is accomplished by simultaneous emission. There seems to be no possibility of an internal fertilization. 8. The bottom conditions play a decisive role in releasing the spawning activities. 9. If, during the spawning time, river lampreys have no favourable spawning ground within reach they usually die without having spawned.
- Subjects
LAMPETRA fluviatilis; SPAWNING; EELS; OSTEICHTHYES; AQUATIC animals; ANIMAL sexual behavior; NEST building; AQUATIC biology
- Publication
Oikos, 1959, Vol 10, Issue 1, p50
- ISSN
0030-1299
- Publication type
Article
- DOI
10.2307/3564906