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Prespawning Behavior, Spawning, and Development of the Brooding Starfish Leptasterias polaris
The Biological Bulletin
|December 28, 2017
Summary
Starfish Leptasterias polaris aggregate and interact before spawning, triggered by decreasing temperatures and daylength. Fertilization occurs when females spawn onto male sperm, ensuring successful reproduction.
Area of Science:
- Marine Biology
- Reproductive Ecology
- Invertebrate Zoology
Background:
- Reproductive behaviors of the starfish Leptasterias polaris are poorly understood.
- Ecological importance of L. polaris reproductive strategies necessitates detailed study.
Purpose of the Study:
- To precisely document the reproductive behavior of Leptasterias polaris before and during spawning.
- To investigate environmental triggers for aggregation and spawning in L. polaris.
Main Methods:
- Laboratory observations of L. polaris spawning under natural environmental conditions.
- Monitoring of aggregative interactions, temperature, and daylength preceding spawning.
- Tracking of embryonic development from fertilization to juvenile stage.
Main Results:
- Starfish exhibited complex aggregative interactions for 7-8 weeks prior to spawning, triggered by decreasing temperatures (<2°C) and daylength (<9h).
- Spermatozoa are negatively buoyant; fertilization is ensured by females spawning onto a sperm layer, which reactivates sperm upon oocyte contact.
- Embryonic development to juvenile stage took 5.5-6 months; brooding behavior appears to primarily serve egg protection and hygiene.
Conclusions:
- Reproductive behavior in L. polaris is strongly influenced by environmental cues, particularly temperature and photoperiod.
- The unique fertilization mechanism ensures reproductive success in the marine environment.
- Brooding behavior in L. polaris is non-essential for embryonic development rate but crucial for offspring survival.
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