Predatory posture and performance in a precocious larval fish targeting evasive copepods

Area of Science:

• Marine Biology
• Ichthyology
• Animal Behavior

Background:

• Predatory fish commonly use a stealthy approach followed by a rapid strike to capture prey.
• Most fish larvae employ an S-start for striking, but clownfish larvae exhibit a different predatory behavior.
• Clownfish larvae (Amphiprion ocellaris) feed on evasive calanoid copepods from a J-shaped position starting at 1 day post-hatch (dph).

Purpose of the Study:

• To quantify the unique J-shaped strike posture of larval clownfish.
• To investigate how this posture changes with larval development and prey evasiveness.
• To understand the predatory strategy of clownfish larvae compared to the typical S-start.

Main Methods:

• Observation of predatory interactions between larval clownfish (1-14 dph) and three developmental stages of the copepod Bestiolina similis.
• Quantification of the J-shaped posture and its changes.
• Measurement of strike performance, including time to capture and peak speed.

Main Results:

• The J-shaped posture of clownfish larvae became less tightly curled (more L-shaped) as they developed.
• Larvae exhibited less curled postures when targeting more evasive adult copepods.
• Strike performance showed only slight improvements with larval age.

Conclusions:

• The J-posture may enable first-feeding larvae to minimize disturbance while approaching sensitive prey.
• This unique hunting strategy represents an alternative to the prototypical S-start in fish larvae.
• The J-posture is a specialized adaptation for larval clownfish preying on evasive copepods.