Crown of Thorns starfish reproduce sexually by releasing eggs and sperm into the water.
Understanding Crown of Thorns Starfish Reproduction
The reproduction of the Crown of Thorns starfish (Acanthaster planci) is a key factor in their population dynamics, particularly during outbreaks that can severely impact coral reefs. Their reproductive process involves spawning, fertilization, and a larval stage.
The Spawning Process
According to the provided reference, Crown-of-thorns starfish exhibit specific conditions and methods for reproduction:
- Timing: Spawning typically occurs from December to April.
- Temperature: This period coincides with warmer water temperatures, around 28°C (approximately 82°F). This optimal temperature triggers spawning.
- Method: The starfish release their gametes (eggs and sperm) directly into the surrounding water.
How Gametes Are Released
The reference states: The starfish release eggs and sperm into the water through pores on the top of their central disc. This external release method is common among many marine invertebrates and is known as broadcast spawning.
Post-Fertilization Development
Once the eggs and sperm are released into the water:
- Fertilization: If conditions are favorable and gametes from different individuals mix, external fertilization occurs in the water column.
- Larval Stage: After fertilization, the eggs develop into larvae.
- Planktonic Phase: These larvae are microscopic and spend a significant period drifting as plankton in the ocean currents.
- Duration: This drifting larval stage lasts from two to four weeks. During this time, they feed on phytoplankton and develop before settling onto a suitable substrate to metamorphose into juvenile starfish.
Key Stages of Reproduction
| Stage | Description | Timing/Duration |
|---|---|---|
| Spawning | Release of eggs and sperm into the water through pores on the central disc. | December to April |
| Fertilization | External fertilization occurs in the water column. | Immediately post-spawning |
| Larval Stage | Eggs develop into planktonic larvae. | 2 to 4 weeks |
| Settlement | Larvae settle and metamorphose into juvenile starfish. | After planktonic stage |
This efficient broadcast spawning method allows for wide dispersal of larvae by currents, which can contribute to the spread of populations across large areas.
Key Takeaways:
- Crown-of-thorns starfish are broadcast spawners.
- They reproduce seasonally, linked to warm water temperatures.
- Gametes are released through pores on the central disc.
- The larval stage is planktonic and lasts several weeks.
Understanding this reproductive cycle is crucial for managing outbreaks of Crown-of-thorns starfish on coral reefs.
