Analysis of the Relative Growth of the Pacific Edible Crab, Cancer magister.

Abstract

Summary An analysis by the method of Huxley of approximately 4000 measurements made on about 1800 individuals of Cancer magister from the Pacific coast of North America is here presented. Slight heterogony has been found in the growth of the majority of its parts. In all aspects of relative growth it is extremely conservative. Changes in form indicate that sexual maturity in the female occurs at a carapace width of about 10 cm. This is confirmed by the size of ovigerous females and by observations of the development of the ovary. The sudden change in the length‐width proportions indicates that sexual maturity is usually attained by a single moult. The size at which male crabs become mature could not be inferred with certainty from the present data. After sexual maturity has been attained the legs of male crabs grow more rapidly than the body and the legs of females continue to grow less rapidly than the body. As a consequence the legs of mature males are longer than those of mature females of corresponding carapace width. A change in the ratio of length to width of the sixth abdominal segment of females has been noted at a carapace width of 7 cm. No other change is known to occur at this size. It is possible that this is a precocious change associated with the approaching sexual maturity. Crabs from south‐eastern Alaska, both male and female, were found to be a little shorter in proportion to their width than the corresponding Boundary Bay crabs. It has been pointed out that most organisms display some heterogony and that bizarre forms must exhibit it to a greater degree than more conservative forms. It has further been pointed out that a strong negative correlation seems to exist between the degree of heterogony and the maximum size of a species. Unfortunately no data justifying speculation upon the causal relationships are available. Cancer magister in all aspects of relative growth displays great conservatism; no high values for k were found for this large and abundant species.

Allometry and Size in Ontogeny and Phylogeny

“…Hamai (1937), in an excellent but unfortunately neglected work, systematically analysed curvilinear departures from simple allometry in terms of differential decline of specific growth rates in the two variables. Smooth log-log curvature was further noted by Weymouth & MacKay (1936) in Cancer magister; A. Xeedham (19 50, p. I I j ) for abdominal growth in Pinnotheres pisum; Kidwell, Gregory & Guilbert (1952) for heart girth in cattle; and Wilson (1953, p. 147) in ' ants.…”

Reproductive Biology of Male Jonah Crab, Cancer Borealis Stimpson, 1859 (Decapoda, Cancridae) on the Scotian Shelf, Northwestern Atlantic

“…In Cancer magister, there also seem to be two phases in chela allometric relationship, with an in ection point at 110 mm CW, corresponding to size at gonadal maturity (Weymouth & Mackay, 1936;Butler, 1960). The change in chela allometry is so slight that Orensanz & Gallucci (1988) did not nd any statistical difference between the two phase-lines.…”

“…Chela allometry data of cancrid crabs relative to reproductive biology are available from Weymouth & Mackay (1936) and Butler (1960) on Cancer magister Dana, 1852, from Campbell & Eagles (1983) on Cancer irroratus Say, 1817, from Orensanz et al (1995) on Cancer magister, C. gracilis Dana, 1852, C. oregonensis (Dana, 1852, and C. productus Randall, 1840, and from Orensanz & Gallucci (1988) on C. gracilis. Partial information on chela morphometry is also reported by Quiles et al (2001) on Cancer bellianus Johnson, 1861, by Carroll (1982) on C. antennarius Stimpson, 1856, and by Carvacho (1989) on C. porteri Rathbun, 1930 andC.…”

“…This size range ; 3, Campbell & Eagles (1983); ¤ fully developed stage 5 gonads; 4, Moriyasu unpubl. data;5, Butler (1960); 5 ¤ , mating pairs from the wild; 5 ¤¤ , mating marks; 6, Weymouth & MacKay (1936); 7, Orensanz & Gallucci (1988);8, Le Foll (1984); 9, Edwards (1979); ¤ "white swollen vasa deferentia"; 10, Edwards (1966).…”

Studies On Decapod Crustacea From the Indian River Region of Florida. Xxv. Carapacial and Abdominal Allometry in Five Species of Subtropical Parthenopid Crabs (Brachyura, Parthenopidae)

“…Studies on the pubertal molt have often used carapace length and width measurements as the sole reference dimensions (Weymouth & McKay, 1936;Newcombe, 1948;Newcombe et al, 1949;Allen, 1962;Gilford, 1962;Hartnoll, 1965b;Herreid, 1967;Griffin, 1970). However, in many brachyurans the relative growth of these two parameters by itself probably provides fewer overt indications of the onset of maturity than do other allometric dimensions.…”