believe they may have solved one of the mysteries of how humpback
whales successfully hunt - and their findings may help beat cancer
in human beings.
It has long
been known that some species of whale hunt by creating a cylindrical
column of bubbles in which fish are corralled. But until now, no-one
knew why the fish had refused to swim out.
A humpback shows its paces
However, Professor Tim Leighton, of the Institute of Sound and
Vibration Research at the University of Southampton, UK, has said he
believes the whales use sound to scare the fish into staying put.
"If sound is propagating through water, the most potent,
naturally occurring entity it can meet is a bubble," he told BBC
World Service's Discovery programme.
The bubbles slow sound down - a beam of sound aimed towards the
bubbles will be trapped, bouncing around within the column at a
speed of 1km/s.
"If [the fish] ever try to leave the net, what they encounter is
a very loud wall of sound," Professor Leighton added.
When humpbacks hunt, up to 30 of them will circle in the deep
water, releasing bubbles.
As these bubbles rise to the surface, they create a column,
inside which fish congregate. The humpback whales will then swim up
from beneath the cylinder and eat the fish.
"We know fish will swim through bubbly water quite happily,"
Professor Leighton explained.
"I think what is happening is that while the whales are producing
this net, they are making a very loud, scary noise.
"As these sounds get trapped within the cylinder of bubbles, the
fish stay within the quiet region."
What is more, the startled fish form a tight school, and so make
a compact meal for the whales when they rise up from beneath the
trap with their mouths open.
There may now be many potential uses for these findings.
Specifically, Professor Leighton said there were many
opportunities for using the acoustic effects of bubbles - especially
in the arena of modern warfare.
"In the oceans, it is becoming very important because our naval
scenarios have moved from being deepwater, where you're looking for
nuclear subs underneath the ice caps, to shallow waters like the
Gulf," he said.
"[There] are many waves breaking, many bubbles, in which you can
hide objects like mines."
The research has potential benefits in medicine, too.
Bubbles can be collapsed while inside the body using ultrasound.
This makes them potentially very useful in seeking out and
destroying dangerous cells.
"We might conceive of one day taking the bubbles and coating
their outer surface, so that as they travel through the body they
can track down particular types of cells," Professor Leighton
"So we put these bubbles in, they spread though the body, they
attach to particular types of cells - perhaps cancer cells - that
you want to get rid of.
"Then if we hit these bubbles with ultrasound, we can collapse
The bubbles would then act like "little injectors", and whatever
was contained within the bubbles would be injected into the
dangerous cells to kill them.