Metamorphosis in the paired species of lampreys, Lampetra fluviatilis (L.) and Lampetra planeri (Bloch) . 2. Quantitative data for body proportions, weights, lengths and sex ratios

Bird, D.J.; Potter, I.C.

Zoological Journal of the Linnean Society 65(2): 145-160


ISSN/ISBN: 0024-4082
Accession: 005886842

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Representatives of the various stages (1-9) in the metamorphosis and short adult life of the brook lamprey, L. planeri, were used to provide quantitative data to describe the pattern of changes that take place during this period of the life cycle. During the transformation of the oral hood into an oral disc, this ventral region of the snout first declines in length before increasing markedly. The branchial region declines in length and remains relatively smaller than in the ammocoete, a feature probably correlated with the concomitant internal changes in the pharynx which permit a change from a unidirectional to a tidal respiratory flow. The eye increases in size only through the initial stages (1-5). The main period of fin enlargement occurs rather later in metamorphosis than the above changes. During maturation the 2 initially separate dorsal fins increase further in height and eventually become separated only by a notch. Differences between the 2 sexes are found in the relative size of the disc and fins, the larger structures of the male probably being related to their greater activity in spawning behavior. Measurements on metamorphosed L. fluviatilis confirm that in this species the eye and disc are relatively larger than in L. planeri. Data are presented which illustrate that in collections taken during the metamorphosis of both species the males are smaller and slightly more numerous than the females and that transformation is initiated at a longer length in L. planeri than in L. fluviatilis.