At Botanical Beach on the west coast of Vancouver Island, young-of-the-year Ligia pallasii appear in spring and early summer.  The earliest of these are from females carrying broods through the winter, while the later ones are from females carrying early springtime broods.  These latter take about 5wk from egg deposition to release.  After a summer’s growth some of the largest females (probably ones from winter broods) may develop a winter brood, but most breed for the first time the following spring when they are about 1yr old. Note that at any given time there are 2 or sometimes 3 generations present in the population. The graph shows the estimated date of release of youngsters from the brood chamber in April 1970. Growth is maximal during spring/summer, and is more or less quiescent over winter. Note the faster growth of males in comparison with females, most notable in the 1970 generation. This is accompanied by an allometric increase in width of carapace as the males mature into their broad-bodied,






female-carrying reproductive state. These males are about 30% larger than females and are likely the dominant “fertilisers” of both winter- and spring-brooding females. It is not known how long a male carries a female, nor whether a certain minimum size is required by a male for amplexus, or if these “super”-males out-compete smaller males for access to females.  Average lifespan is 1.5yr for females, and just over 2yr for males that survive past springtime of their second year. Carefoot 1973 Mar Biol 18: 302.

A juvenile Ligia pallasii emerges
from its mother's brood pouch 4X