Tuesday, June 10, 2014

Insects' underwater sex secrets



Scientists in Taiwan have revealed how a diving beetle hangs on to its mate underwater.


The micro-scale study revealed how bristles on male beetles' legs attach to females.


Tiny suckers on these bristles stick to the females' bodies.


As well as shedding light on evolution at the very tiny scale, understanding this could inspire the design of devices for underwater attachment in engineering.


The results are published in the Royal Society journal Interface.


The team, led by Dr Kai-Jung Chi from National Chung Hsing University in Taiwan, directly measured the gripping force of the 'attachment devices' on the leg bristles of two diving beetle species.


Microscopic images reveal that one of the species they studied - a more primitive insect - has a spatula-like attachment.


The other has evolved circular suckers on the end of each leg bristle, which look like a microscopic plungers.


While these tiny plungers created a stronger attachment, the more primitive bristles had some sticky, aquatic secrets.


Tiny channels between the hairs in the more primitive beetle appear to produce a sort of glue.


And, as grisly as it may sound, the fact that these bristles form a weaker attachment and can move around on the female's body more freely means that the male beetle is able to 'resist the female's erratic swimming movements', which she may employ to dislodge an unwanted suitor.


The researchers conclude that their mechanical experiments show that the 'later-evolved suction-cup-shaped circular' bristles give male diving beetles a mating advantage.


And all of this detailed insight into aquatic copulation may inspire a future 'underwater Velcro'.