GROWTH AT MOLT AND MOLTING SEASONALITY OF THE SPIDER CRAB, MAJA-SQUINADO (HERBST) (DECAPODA, MAJIDAE) IN EXPERIMENTAL CONDITIONS - IMPLICATIONS FOR JUVENILE LIFE-HISTORY
E. Gonzalezgurriaran et al., GROWTH AT MOLT AND MOLTING SEASONALITY OF THE SPIDER CRAB, MAJA-SQUINADO (HERBST) (DECAPODA, MAJIDAE) IN EXPERIMENTAL CONDITIONS - IMPLICATIONS FOR JUVENILE LIFE-HISTORY, Journal of experimental marine biology and ecology, 189(1-2), 1995, pp. 183-203
Prepubertal growth (moult size increment and duration of the intermoul
t period) and the seasonality of moulting in the spider crab Maja squi
nado from the southern coast of Galicia (NW Spain) were analyzed under
experimental conditions (laboratory and extensive culture). Two annua
l moult periods were observed; the first corresponded to the prepubert
al moults that take place in spring (reaching their peak at the end of
March and in April), and the second to the pubertal (terminal) moult
in summer during which time the animals reach morphometric maturity. T
he peak for the terminal moults within the population took place in Ju
ne in the experiment under extensive culture conditions and in July an
d August in the laboratory and in the held, where the maximum annual t
emperatures were lower and occurred later (17-19 degrees C in August a
nd September) than in the former experiment (21-22 degrees C in July).
The modal number of annual moults per crab was 2, and ranged between
1 and 3. The number of annual moults decreased with the size of the an
imal at the beginning of the moulting season, and the animals delayed
ecdysis in accordance with body size (there was a significant positive
correlation between moulting date and body size within each of the tw
o periods). There were no significant differences between males and fe
males in moulting seasonality. In the laboratory, the duration of the
intermoult period prior to the pubertal moult was estimated to be 104
days, and for the prepubertal moult it was 85 days. For specimens betw
een 60 and 130 mm carapace length (CL), the moult size increment was e
stimated to be an average of 29 mm CL, which constitutes an average of
32% of the pre-ecdysial size. There were no significant differences i
n the moult increment between sexes or between the laboratory and exte
nsive culture experiments. There were however significant differences
between the pubertal and non-puberty moults (27 and 36%, respectively)
. This was due to the larger sizes of the prepubertal animals, and to
the negative correlation between body size and the percentage moult in
crement (the absolute moult size increment was positively correlated w
ith CL). The samplings carried out in juvenile habitats in shallow are
as