Pattern Polymorphism and Predation in the Shore Crab, Carcinus Maenas (L.)

Juvenile C. maenas are highly polymorphic with respect to carapace colour patterns. A bold pattern may be cryptic when a crab is small, but conspicuous when it grows. 2 mechanisms are possible to explain the disappearance of juvenile patterns with increasing age: pigment deposition possibly accelera...

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Bibliographic Details
Published in:Crustaceana 1975-01, Vol.28 (3), p.316-319
Main Author: Hogarth, Peter J
Format: Article
Language:English
Subjects:
Adaptive polymorphism
Carcinus maenas
Crabs
Marine
Notes and News
Population genetics
Population size
Young animals
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Summary:Juvenile C. maenas are highly polymorphic with respect to carapace colour patterns. A bold pattern may be cryptic when a crab is small, but conspicuous when it grows. 2 mechanisms are possible to explain the disappearance of juvenile patterns with increasing age: pigment deposition possibly accelerated or delayed by different backgrounds or unusual predation selectively removing crabs with conspicuous patterns. The maximum sizes of high contrast crabs within samples are plotted against the corresponding figures for low contrast crabs. The correlation (r = 0.66; p < 0.01) between the 2 indicates that high and low contrast Carcinus both disappear from the populations studied at approx the same size. High contrast patterns do not disappear earlier than low contrast patterns with increasing size; it seems unlikely therefore, that differential visual predation of high contrast patterns is an important factor in determining differences in pattern frequencies, with size.
ISSN:0011-216X
1568-5403
0011-216X
DOI:10.1163/156854075X00621