Australasian Science: Australia's authority on science since 1938

Eggs Lure the Right Sperm

The survival of mussel larvae is affected by chemical signals emitted from the females’ eggs, according to a study published in the Proceedings of The Royal Society B.

Prof Jon Evans of The University of Western Australia found that mussel sperm exhibit consistent but differential preferences for chemical cues secreted from the eggs of different females. These preferences predicted both the compatibility of sperm and eggs at fertilisation and the chances of the larvae surviving.

“We know that eggs emit chemical cues that attract sperm,” Evans said. “We also know from previous studies that sperm are attracted to eggs from the same species. What this research shows is that there are differences in chemical cues from each egg, and somehow the sperm is exhibiting preferences in response to those cues that leads to healthier offspring.”

The study also found that by experimentally separating the chemical cues from eggs, sperm swimming behaviour was influenced by the particular combination of sperm and chemical cues, and that these patterns of sperm behaviour predicted fertilisation and survival. The researchers concluded that sperm are fine-tuned to respond to chemical cues emitted from genetically compatible eggs, thus maximising fertilisation and larval survival.

“So what we found is that there is a survival advantage for offspring of females who send out the right cues to attract the right sperm,” Evans said.

Evans’ team is now studying the biochemical and molecular mechanisms underlying these patterns in order to better understand how sperm and eggs interact in the sea.