. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 36 HAMEL AND A. MERCIER 100. u o 40" 20 Spawning Types of contact B Superposition Q Intimate B Light D No contact N D 1992 1993 Figure 3. Leptasterias polaris. Temporal evolution of the prespawning aggregative behavior recorded several times a week for a 3-month period. For each date, the percentage of individuals involved in a particular type of contact was recorded. when feeding did not disturb the contact behavior between the individuals. Environmental factors seem to be involved in the ini- tiation and develop
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 36 HAMEL AND A. MERCIER 100. u o 40" 20 Spawning Types of contact B Superposition Q Intimate B Light D No contact N D 1992 1993 Figure 3. Leptasterias polaris. Temporal evolution of the prespawning aggregative behavior recorded several times a week for a 3-month period. For each date, the percentage of individuals involved in a particular type of contact was recorded. when feeding did not disturb the contact behavior between the individuals. Environmental factors seem to be involved in the ini- tiation and development of the prespawning aggregative behaviors. No aggregation occurred among individuals maintained at constant temperature and photoperiod, but grouping did take place among individuals kept in total darkness with natural temperature. Spawning Our experimental information includes actual obser- vations of spawning events in 4 females and 3 males and additional indications from sperm agglutinates on many males and on the substrate. We also observed more than 20 brooding females, which were always discovered within 24 h of spawning. We examined the correlations of all our observations with environmental factors (Fig. 2), which were similar in the laboratory and in the field. Spawning occurred in our tanks from 19 December to 12 January, which roughly corresponded to the period when we observed spawning in the field. During spawning events, the starfish stayed close together, although there was a net decrease in frequency of contact (Fig. 3). The spawning individuals were not paired or superposed. Spawning events. Figure 4 schematically illustrates the spawning behavior we observed in the experimental tanks. When a male spawned, it elevated the central disk, stand- ing on the curved tip of its arms, and emitted sperm as a whitish stream from the six interradial aboral gonopores. Emission continued for more than an hour. Qualitative observations showed the sperm to be negatively b
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
