. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 34 HAMEL AND A. MERCIER. Figure 1. Photographs illustrating the prespavvning aggregations of Leptasterias polaris in the laboratory. (A) Superposition of two individ- uals. (B) Massive aggregation of starfish. Sperm behavior The term dry sperm refers to undiluted, freshly removed sperm from the mature gonads of at least two males. Ac- tivated oocytes were obtained by spreading freshly re- moved female gonads (including gonoducts) in a petri dish filled with 5 ml of 1-methyladenine 1(T5 M, yielding naturally spawned ooc
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 34 HAMEL AND A. MERCIER. Figure 1. Photographs illustrating the prespavvning aggregations of Leptasterias polaris in the laboratory. (A) Superposition of two individ- uals. (B) Massive aggregation of starfish. Sperm behavior The term dry sperm refers to undiluted, freshly removed sperm from the mature gonads of at least two males. Ac- tivated oocytes were obtained by spreading freshly re- moved female gonads (including gonoducts) in a petri dish filled with 5 ml of 1-methyladenine 1(T5 M, yielding naturally spawned oocytes after about 45 min of exposure. The buoyancy, capacity for adherence to the substrate, and motility of the sperm were used to describe its be- havior in seawater. All experiments on sperm behavior were conducted at a temperature close to the one recorded during the spawning period (2-4°C). All live observations of sperm samples were made under a light microscope (100-400X) and the sperm was kept cool by surrounding the slide with ice cubes. The speed of the spermatozoa was evaluated with a graduated lens, by calculating the number of bars traveled per second. Verifications were undertaken to discard any behavior induced by the light of the microscope or false sperm velocity induced by the sperm-glass interaction (thigmotaxis). For more than 7 h we continuously recorded the speed, orientation, and flagellar activity of sperm before and after the samples were diluted in seawater (150 /jl of dry sperm in 1 I). To examine the behavior of sperm in the water column and on the bottom, the protocol was carried out in both still and agitated (current of 7cm-s~') water. Samples were taken from the bottom of the beaker and at a middle depth every minute for 15 min, then every 15 min for 7 h, and finally at 24-h intervals until the sper- matozoa were dead. This protocol, which was repeated twice using repetitive independent measurements, also allowed the estimation of the sperm conce
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