Why is there no sperm competition in a pipefish with externally brooding males? Insights from sperm activation and morphology

Abstract

Nerophis ophidion sperm activation and morphology were investigated with the aim of explaining the apparent lack of sperm competition in this syngnathid with externally brooding males. Nerophis ophidion sperm were activated by a mixture of ovarian fluid and sea water, but not by sea water alone. This indicated that sperm were not shed into the water but needed to be released near the eggs, which probably restrained sperm competition. © 2006 The Fisheries Society of the British Isles.