Who would have thought: an eerie green glow that has baffled sailors for ages is almost like a neon sea-based billboard selling sex – for fireworms.

According to a paper published in last months issue of the journal Invertebrate Biology, female marine fireworms secrete a slimy glow-in-the-dark substance into the water to attract male fireworms during the summer mating season.

A day or two before each quarter moon phase – for about a half an hour at a time – the females spread the message that fertile sex cells are about to be released into the water. Male fireworms are lured to the area and then also release their sex cells into the water, resulting in fertilisation. The scientists suspect that a specific protein in the slimy secretion may be responsible for the light flashes.

If the molecular mechanism behind the reaction can be deciphered the protein may prove very useful as a biomarker in a range of biomedical and bioengineering applications.