Mate competition during pseudocopulation in shipworms.

Area of Science:

• Marine Biology
• Invertebrate Zoology
• Reproductive Ecology

Background:

• Shipworms (bivalves) are crucial for marine ecosystem functions like biodegradation and nutrient cycling.
• Their wood-boring lifestyle drives diverse reproductive adaptations, including unique fertilization strategies.
• Pseudocopulation, a rare direct fertilization method, is known in shipworms but poorly understood.

Purpose of the Study:

• To document pseudocopulation in the giant feathery shipworm (Bankia setacea) using video evidence.
• To identify and describe novel competitive behaviors associated with shipworm reproduction.
• To explore the evolutionary pressures that may lead to large size in shipworm species employing pseudocopulation.

Main Methods:

• In-situ video recording of shipworm interactions.
• Behavioral analysis of observed reproductive and competitive activities.
• Comparative ecological and evolutionary interpretation of findings.

Main Results:

• Direct video evidence of pseudocopulation in Bankia setacea was obtained.
• Novel competitive behaviors, including siphon wrestling and mate guarding, were documented.
• Sperm removal from rivals' siphons was observed, indicating reproductive competition.

Conclusions:

• Pseudocopulation is a confirmed reproductive strategy in Bankia setacea.
• Competitive behaviors suggest selection for larger size and longer siphons in pseudocopulating shipworms.
• These findings enhance understanding of shipworm reproductive diversity and evolution.