CLOSE examination of the seahorse, below, has
shown that the cute little fish is a master of stealth, using streamlined
features in its head to sneak up on its prey, scientists reported.
At first glance, the seahorse is an
unlikely candidate for hunter of the year.
Swimming vertically, its tail curled, it
progresses through coral reefs and shallow beds of seagrass thanks to a little
dorsal fin that flutters three dozen times per second.
Its top speed is no more than 150 cms an
hour, a pace politely described as dignified.
By this yardstick, the species should not
give planktonic copepods any sleepless nights. These are tiny crustaceans that
are super-attuned to any water movement caused by an advancing
predator.
The critters can move at super-speed,
reacting to a peril within as little as two thousandths of a
second.
They can propel themselves away at the
speed of than 500 body lengths per second -- the rough equivalent of a human
clearing 10 football fields in a single leap.
Given these challenges, how is the
ponderous seahorse able to eat?
The answer, according to a study published
in the journal Nature Communications, lies in the extraordinarily hydrodynamic
-- the watery equivalent of aerodynamic -- shape of its head.
With a long snout and sleek cheekbones,
the organ offers minimal resistance to water, which enables the seahorse to
ever-so-slowly sidle up on a copepod without being detected.
Once it gets within about 1mm, the
seahorse strikes, using a system of elastic-like tendons in its neck to drive
its head forward, covering the distance in less than one thousandth of a
second.
Laboratory tests using 3D holographic
video found that dwarf seahorses (Hippocampus zosterae) were 84 percent
successful at getting within range of a copepod without triggering an escape
response.
Once they were in the 1mm strike zone,
they were 94 percent successful in grabbing their prey.
The study, led by Brad Gemmell at the
University of Texas at Austin, suggests that these insights could have
applications in industry, when manufacturing processes need hydrodynamic
microstructures that can be immersed into a fluid yet not disturb
it.
With thanks to The
Australian
One of the smallest vertebrates in the world lives in the tropical
Pacific--the pygmy seahorse. Belonging to the same genus as their
larger cousins but reaching a maximum size of about an inch, its no
wonder that many of these miniature species have only been discovered
within the last decade.
Currently there are nine known species but,
with scientists and divers exploring more reefs and making better
observations, surely there will be more discoveries to come.
Jean-Michel Cousteau and his Ocean Futures Society team were extremely
fortunate to get an up-close look at this most unlikely of creatures in
the waters of Papua New Guinea. They were awed by the miracle of
evolution that creates such miniature masterpieces.
