. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. REPRODUCTIVE BEHAVIOR OF LEPTASTER1AS POLARIS 35 18" 16- 14 12 ID- S' 6 4 2" 0 Prespawning Spawning Developmental biology Temperature (°C) Metamorphosis. O N 1992 D M A 1993 M Figure 2. Variation of environmental factors during the reproductive season of Leptasterias polaris in the experimental tanks. The arrow points to the beginning of embryo metamorphosis. of seawater and periodically collected water samples at the surface and on the sides of the dish. The spermatozoan concentrations of the samples were evaluate
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. REPRODUCTIVE BEHAVIOR OF LEPTASTER1AS POLARIS 35 18" 16- 14 12 ID- S' 6 4 2" 0 Prespawning Spawning Developmental biology Temperature (°C) Metamorphosis. O N 1992 D M A 1993 M Figure 2. Variation of environmental factors during the reproductive season of Leptasterias polaris in the experimental tanks. The arrow points to the beginning of embryo metamorphosis. of seawater and periodically collected water samples at the surface and on the sides of the dish. The spermatozoan concentrations of the samples were evaluated with a he- macytometer under a light microscope. This experiment was simultaneously performed on live and dead dry sperm of Leptasterias polaris and on dry sperm from Asterias vulgaris. Strongylocentrotus droebachiensis, and Cucu- nuiria fmndosa. Sperm longevity could thus be compared for those species under the same conditions. Development Whenever we discovered a naturally spawned egg mass, whether brooded or not, it was left undisturbed in the tank so that we could examine development under natural variations of environmental factors. Nonbrooded egg masses were kept clean by periodically agitating the water. Samples were regularly collected with pipettes, from fer- tilization to young starfish stage, and transferred to 4% formaldehyde/seawater for later examination with light microscopy. These embryos also served to determine de- velopmental kinetics and growth. During the first hour, samples were collected every 2-5 min, then about every day until the brachiolaria stage, and finally once a week. A new stage was considered attained when 50-60% of the embryos reached it. Maximum embryo diameters were measured under a light microscope equipped with a grad- uated lens. Results Prespawning behavior During summer and early fall, the well-fed starfish clearly avoided each other. Contacts among starfish began in mid-October, coinciding with the first significant de- crease of te
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
