Tuesday, 19 August 2008

Conniving courters

When it comes to courting, male fish sometimes pretend they’re after love when they actually want something else -- eggs for dinner.

Reporting in the Journal of Fish Biology, Suzanne Grey and colleagues followed male Telmatherina sarasinorum, also known as sailfin silversides, as they foraged for food in their native habitat, the Malili Lakes of Indonesia. Curiously, the brightly coloured male T. sarasinorum would occasionally display ritual courting behaviour to the females of a related species, Telmatherina antoniae. But whereas males and females normally quiver at the end of the courting ritual, indicating that eggs and sperm have been released, only the female fish would quiver in these curious courtships. And when the females swam off, these males would immediatly begin eating the eggs. This deceptive behaviour, dubbed ‘sneaky egg-eating’, has never been described before.

Sneaky-egg eating occurs at a low but appreciable frequency, the authors note, and probably evolved in part because of a lack of alternative sources of nutrition.