Nature's genius: Dive deep, stay dry
Researchers have discovered how deep-diving birds such as cormorants ‘spontaneously de-wet’ as they emerge from water, using unique feather structures.
The trick could now be copied to produce fabrics to make super-efficient drysuits.
Previously, it was known that the feathers of water birds create a pocket of air, known as a ‘plastron’ between the feather and the skin of the bird.
This air protects the skin so that the bird doesn’t actually get wet when submerged. This effect combines with ‘preen oil’, a waxy substance produced by the birds, to keep water out.
The new study, carried out by scientists from MIT and Museum researcher Prof Andrew Parker, found that deeper than a few metres, the plastron collapses. So, for birds such as cormorants, which can dive deeper than 40 metres, their skin gets wet during a dive.
However, the team found that as the bird re-emerges, and the pressure of the overlying water drops, the feather structures push the water back out.
‘It’s totally reversible,’ said Prof Parker. ‘The bird gets into trouble, and then instantly gets back out of trouble again.’
Cormorants will sit and stretch their wings after a dive, and this seems to help the movement of water being squeezed out of its feather structures.
Copying nature’s designs
Getting dry quickly is important for both birds and humans, to prevent rapid changes in temperature and thermal shock.
Prof Parker specialises in ‘biomimetics’, the imitation of nature’s structures and materials to solve human problems.
The structures on cormorant feathers could be adapted into fabrics that would greatly enhance divers’ drysuits. Prof Parker and his colleagues from MIT are planning to investigate the feathers of even deeper divers, such as auks and penguins, which can dive to depths of up to 500 metres.
Prof Parker is also researching the way cacti collect morning dew and fog water in Africa. Mimicking this system could open up new ways of harvesting water in low-rainfall areas.