Biology Reference
In-Depth Information
of rasping tongue (piston), changes in respiration, and added protection for
the pericardial cavity. The eye of the blind larval completes its development
with enlargement and the appearance of a functioning retina and a
prominent pupil and iris. There are many changes in blood parameters,
such as the appearance of adult erythrocytes, adult hemoglobin, adult
albumin, and a new iron-binding protein. Some of these changing blood
parameters are refl ected in re-distribution of iron such that some organs, like
the liver, become iron loaded during metamorphosis and into adult life to
levels that would be toxic in many vertebrates. Changes in the epithelium
of the gills, intestines and the kidney tubules are in preparation for the
potential for saltwater acclimation in adults of anadromous species. Theses
latter changes, and many described above that are related to adult feeding,
also occur in larval of non-parasitic species during their metamorphosis.
The post-metamorphic adults of these species never feed or leave their
freshwater natal stream, but commence immediately into sexual maturation.
The fact that these changes still occur in non-parasitic species is a refl ection
of both the evolutionary relationship between the two adult life history
types and also the interesting evolutionary history of metamorphosis as a
development strategy among lampreys.
Acknowledgements
The authors are most grateful for the generous contribution of Dr. John
R. Gosche, University of Nevada, for the photographs of metamorphosing
stages of
P. marinus
following induction. Research conducted in the
laboratory of R.G.M. is supported by grants from the Natural Sciences
and Engineering Research Council of Canada (NSERC; Discovery, and
Research Tools and Instruments Grants) and the Canada Foundation for
Innovation. J.H.Y. acknowledges the long-term research support of NSERC
(Discovery and Strategic Grants) and its forerunner, and the very timely
funding from the Great Lakes Fishery Commission, the Medical Research
Council of Canada, and the Hospital for Sick Childrens Foundation ( Sick
Kids Foundation, Toronto).
References
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Barrington, E.J.W. 1972. The endostyle and thyroid gland. In: M.W. Hardisty and I.C.
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