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An examination of variable growth rates in the tropical squid Sepioteuthis lessoniana: a whole animal and reductionist approach


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Semmens, JM and Moltschaniwskyj, NA 2000 , 'An examination of variable growth rates in the tropical squid Sepioteuthis lessoniana: a whole animal and reductionist approach' , Marine Ecology Progress Series, vol. 193 , pp. 135-141 .

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Squids typically demonstrate considerable plasticity in individual growth rates. However,
it is not known if individuals growing at different rates also differ at lower levels of organisation. We
wished to determine if Seploteuthis lessoniana individuals that were larger than predicted for their age
dlffered in their digestive gland and mantle muscle tissue proximal composition or mantle muscle
structure, compared with individuals that were smaller for their age than predicted. The residual, the
difference between the observed size-at-age and that predicted by the growth equation, was used as a
measure of the difference in an individual's lifetime growth from the population average. Individual
squid varied considerably in their size-at-age, with juveniles showing less variation than adults. Juverules
had greater concentrations of lipid in their muscle tissue, perhaps due to an emphasis on storing
energy reserves in this critical period of thelr life. Differences in biochemical constituents in both the
digestive gland and muscle tissue were not related to the size-at-age of individuals, despite biochemical
make-up being the lowest organisational level of growth. This may be due to whole animal growth
and changes in biochemical composition occurring on different time scales. There was no relationship
between the size-at-age of individuals and average mantle muscle fibre size. A strong relationship,
however, existed between the size of mantle muscle blocks and the size-at-age of individuals for both
juvenile and adult individuals, suggesting that larger muscle blocks are related to both body size and
faster individual growth rates. This study demonstrates a clear relationship between mantle muscle
structure and growth and the size-at-age of S. lessoniana individuals.

Item Type: Article
Authors/Creators:Semmens, JM and Moltschaniwskyj, NA
Keywords: Squid . Size-at-age . Condition . Muscle tissue . Digestive gland
Journal or Publication Title: Marine Ecology Progress Series
ISSN: Print 0171-8630 Online 1616-1599
Additional Information:

© Inter-Research 2000

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