While most of us know cuttlefish as the
little surfboard-shaped bones we found at the beach and took home for
the budgie - few of us realize the svengali-like talents of that bone's
original owner.
According to marine biologist, Andy Dunstan, many divers look at a
passing cuttlefish for just a moment before swimming on: "unaware that
these little critters can turn an ordinary dive into a legendary
experience."
Andy is senior scientist with Undersea Explorer - a combined scientific
research and adventure dive vessel working out of Port Douglas,
Queensland. Together with Dr Mark Norman from the University of
Melbourne, he has been studying the incidence, breeding sites and
behaviour of cuttlefish located along the Ribbon Reefs of the Great
Barrier Reef.
"Cuttlefish can alter the colour, pattern and texture of their skin to
suit a variety of purposes," says Andy, "making them masters of
disguise.
"For instance, a male cuttlefish will aggressively stand guard over a
female, while she lays her eggs, to keep away predators and other
competing males. But another male cuttlefish can still access the female
by adopting female colouration along the side of its body facing the
defending male as it passes by. At the same time, it will retain its
male colouration on the side facing the female.
The Reef Cuttlefish
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"Cuttlefish
can also control their patterning to hypnotise prey. They'll point the
tips of their arms towards the potential victim and begin running skinny
bands of colour from the back of their body down to their tentacle tips.
The appearance of concentric circles flowing towards the onlooker,
induces a hypnotic effect mesmerizing it onto the menu.
"One of the most fascinating things a diver can see, however, is a
developing cuttlefish still inside its egg. Each one takes about six
weeks to gestate but the egg becomes transparent after the first week.
The females will lay them between the coral fingers of a boulder-shaped
coral, where they gradually transform from a pointed oval-like shape
into a ping-pong ball shape - wedging them firmly into place. Inside the
shell the tiny cuttlefish appears to be fully-formed and attached to a
yoke. You can even see them practicing their colour and texture changes.
"When ready to hatch, they use the spike that you see at the tip of a
cuttlebone to scratch and crack their way out. They are born with a
brain, eyes and well developed nervous system; and are ready to assume
the shapes and patterns of seaweed or rocks or other forms of
camouflage. They use their cuttlebone as a floatation device. They pump
is with ammonia - which is lighter than water and produced in their
waste products - to control their buoyancy.
"Most of these critters will live hard and die young, growing quickly
but achieving a life span of only one to three years.
"As a diver, the best way to begin observing a cuttlefish is by
approaching only to the point where you don't disturb its behaviour. The
classic sign that you're invading a cuttlefish's space is when it lifts
its middle two arms over its head and then bends them. Somehow they
manage to look angry too so you'll probably get the hint."
For more information on cuttlefish and the Undersea Explorer cephalopod
project
The tiny Flamboyant Cuttlefish
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