. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. Aug. 11,1995 (n=417) 30 10 Mar 5, 1996 (n=16) 01 23456789101112 Length(mm) 01 23456789101112 Length (mm) Figure I. Size frequency distribution of Sinaechimicyamiu nun from October 1994 to March 1996. Arrows indicate the division between two size groups on each graph except the last two, in which the number of specimens was not sufficient for groups to be discerned. Maturity of gametes Only large-sized individuals were able to spawn in re- sponse to injection of solution during the spawning season. The 33 male and 32 fem
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. Aug. 11,1995 (n=417) 30 10 Mar 5, 1996 (n=16) 01 23456789101112 Length(mm) 01 23456789101112 Length (mm) Figure I. Size frequency distribution of Sinaechimicyamiu nun from October 1994 to March 1996. Arrows indicate the division between two size groups on each graph except the last two, in which the number of specimens was not sufficient for groups to be discerned. Maturity of gametes Only large-sized individuals were able to spawn in re- sponse to injection of solution during the spawning season. The 33 male and 32 female sand dollars exam- ined during the spawning season showed no significant sex-related difference in size distribution. Individuals with mature oocytes or sperm were between and mm in length (Fig. 2). The growth curve and comparison with Scaphechinus mirabilis Since the two size groups of S. mat were distinct in degree of maturity, the groups were considered to repre- sent different ages: specimens belonging to the small-size groupwere 1 year younger than their larger counterparts. The extra-large individual ( mm in length) was con- sidered to be a year older than the members of the large- size group. This sand dollar spawns annually, therefore the 1995 small-size and large-size groups were assumed to be different age groups spawned in 1994 and 1993. respec- tively. Consequently, the growth rates of the first year and the second year were estimated from the age (in 30 -, w 25 - ro u I 20 '^ 15 - o % 10 5 -I Spawning individuals Non-spawning individuals. 8 34567 Length (mm) Figure 2. Size and maturity. Only large individuals are mature in spawning season. 9. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Marine Biological Laboratory (Woods Hole, Mass. ); Marine Biological Laboratory (Woods Hole
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
