午夜福利1000集合

THE hygiene secrets of pilot whales might hold the key to environmentally
friendly paint for ships. It seems the whales have specially adapted skin that
repels would-be hangers-on.

Christoph Baum and a team from the Hanover School of Veterinary Medicine in
Germany have discovered that a pilot whale鈥檚 skin has a specialised
nano-structure that stops the build-up of microscopic organisms such as barnacle
larvae. They plan to mimic the idea in an anti-fouling paint.

The finding may also explain why cetaceans often leap acrobatically out of
the water. Because their skin is hydrophilic, larvae, bugs and other
contaminants prefer to latch onto air bubbles on the skin鈥檚 surface. By crashing
back into the sea the whales create streams of air bubbles that help dislodge
the freeloaders.

Baum and his team examined freeze-dried samples of pilot whale skin under
a cryo-scanning electron microscope. They discovered a surface made up of
tiny pores 0.1 micrometres across surrounded by raised 鈥渘anoridges鈥�. In between
the ridges is a rubber-like gel containing enzymes that denature proteins and
carbohydrates. The gel, which oozes out of the gaps between skin cells, is
replenished as the whale sheds its skin.

Baum thinks that organisms such as bacteria and diatoms have trouble sticking
to the ridge edges, which provide little purchase. And if they try hanging onto
the gel the enzymes will attack them. Without these pioneers, larger creatures
such as crustacean or mollusc larvae have a hard time colonising the whale鈥檚
skin.

For whales, a clear skin is more than just a cosmetic nicety. It is vital for
maintaining maximum swimming speed and performance, says Baum. He suspects that
keeping down the energy costs of swimming is important for the whale鈥檚
survival.

The group intends to patent a version of the pilot whale鈥檚 skin as a more
eco-friendly alternative to existing anti-fouling paints. To copy the skin, Baum
plans on using a variety of biodegradable materials.

A hard polymer matrix would replace the gel. Silica crystals embedded in the
matrix will provide the nanoridges and the whole structure can be
鈥渟elf-polishing鈥�. But this means it will gradually wear away in seawater, and
have to be reapplied every five years or so.

The market is crying out for such products, says Kevin Thomas at the Centre
for Environment, Fisheries and Aquaculture Science in Burnham, Essex. He
predicts that demand for a green alternative will grow even further when the
notorious anti-fouling chemical tributyltin (TBT) is banned in 2003.

This toxic chemical persists for a long time in the environment and damages a
variety of marine life. Although safer alternatives are now available, many
still have some impact on the environment.