Recruitment to the reef
 

Explanations for answers to quiz on the adaptive value of a pelagic drifting phase in the life cycle of a coral-reef fish (the least likely explanation is shown in orange:

Reduces contact with reef-based predators during early development. Yes, this is certainly one possibility.

Allows dispersal to new habitats. Yes, this is the most commonly accepted explanation. Dispersal is also recognised as the primary function of the larval stage of most marine invertebrates

Pelagic drifting minimises energy expenditure. Yes. The larvae are relatively small, their swimming powers generally feeble, and the distances vast. Ocean currents provide the means for large-scale dispersal with minimum energy expenditure.

If the larvae drift away, there is less chance of them being smashed on the reef by waves. If this were true, it would suggest that larval fishes would be more abundant on the lee sides of islands, and this has not been shown to be the case.

Permits better exploitation of patchy food resources. Yes. Island-based reef systems throughout the Caribbean region can be considered "patches"; hence, long-distance drifting is one way (perhaps the only way) that they can be colonised.

 
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