. The Biological bulletin. Biology; Zoology; Marine biology. 190 M. A. SEWELL ducing a five-tentacled pentactula that has a calcareous ring. Pentactulae can move freely in the ovarian tubule (Everingham, 1961; Sewell and Chia, 1994). Development to the pentactula stage occurs in about 10-14 days, so embryos have a calcareous ring for approximately 93% of the 30-week brooding period (Sewell and Chia, 1994). During dissections, dead pentactulae were observed in the ovarian tubules, identified by a discolored body wall (Fig. lA), closed tentacles, incompletely connected gut (Fig. IB), or contorte
. The Biological bulletin. Biology; Zoology; Marine biology. 190 M. A. SEWELL ducing a five-tentacled pentactula that has a calcareous ring. Pentactulae can move freely in the ovarian tubule (Everingham, 1961; Sewell and Chia, 1994). Development to the pentactula stage occurs in about 10-14 days, so embryos have a calcareous ring for approximately 93% of the 30-week brooding period (Sewell and Chia, 1994). During dissections, dead pentactulae were observed in the ovarian tubules, identified by a discolored body wall (Fig. lA), closed tentacles, incompletely connected gut (Fig. IB), or contorted position. In advanced stages of resorption, the body of the pentactula was a "ghost" around the calcareous ring (Fig. IC), or the calcareous ring was the only structure remaining in the ovarian tubule (Fig. 1D). By totaling the number of living pentactulae, dead pentactulae, and calcareous rings, the initial number of brooded pentactulae (A'^^,) could be determined and mortality calculated. Mortality of pentactulae during brooding varied be- tween females, ranging from 0% to 100%, with higher and more variable values during the last 3 months of brooding (Table I, Fig. 2). Differences were also observed in pen- tactulae mortality between both collection sites and years. Site 2 had a higher mean percent mortality in all samples in both years (Table I), and the mean percent mortaUty was higher in each month during 1990-1991 than in 1989-1990 (Table I, Fig. 2). Females generally brooded a lower number of pentactulae (Table I), and the number of females that had lost the entire brood was higher in the 1990-1991 reproductive season (1989-1990: 1 female; 1990-1991: 8 females; Fig. 2); a season that was marked by unusually cold conditions in December and January (days with temperatures below 0°C in December and January: 1989-1990 = 9 d; 1990-1991 = 25 d; P. Janitis, unpub. data). Instantaneous mortality Estimates of instantaneous mortality (day"^') were cal- culated f
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