TV Program Description
Original PBS Broadcast Date: April 3, 2007
Join NOVA on a voyage beneath the
waves, where you'll discover a bizarre, alien-like creature like no
other. It's an animal with eight sucker-covered arms growing out of its
head, three hearts pumping its blue-green blood, and a doughnut-shaped brain.
It has the ability to change its color and shape to blend in with seaweed and
rocks, and it has a knack for switching on electrifying light shows that dazzle
its prey. Perhaps most surprising of all, this animal is quite intelligent,
with a highly complex brain. In this program, underwater cameras capture the
extraordinary, transformative powers of the cuttlefish.
Not a fish at all, the cuttlefish
is a cousin to the more well-known octopus and squid. Together, they are a part
of the class of marine mollusks (soft-bodied animals without a spine) called
cephalopods, or "head-footers." But while cuttlefish are lesser
known, they are very clever. In fact, they have one of the biggest
brain-to-body ratios of all invertebrates.
They also have a special talent.
Mark Norman, a marine biologist and senior curator from Australia's
Museum Victoria, is one of the film's featured experts and has studied
cuttlefish for over 20 years. According to Norman, it is the cuttlefish's
amazing capacity to rapidly change its color, pattern, and shape that makes
this creature so intriguing. By pushing up different parts of its skin, it can
camouflage itself against the reef. And with the striking displays of color and
light on its skin, it can appear like an alien spaceship hovering in the water,
intimidating mating rivals or even hypnotizing a tasty morsel like a crab
before attacking it (see Quick Change Artists).
The program introduces viewers to
the elusive Broadband cuttlefish, known for its particularly flashy light
shows. By presenting the cuttlefish with various lures, including small crabs
and a toy lobster, marine biologists seek to find out what makes this cuttlefish put on its amazing light displays, as well
as whether it is intelligent enough to quickly understand if a lure is
unattainable. (It seems to be: it only takes a few tries for a cuttlefish to
lose interest after determining that a crab inside a glass jar cannot be
caught.)
So how do cuttlefish develop their
visual pyrotechnics? At the Marine Biological Laboratory in Massachusetts,
Roger Hanlon shows viewers how it's done. The secret, he explains, lies
in specialized layers of skin cells. The top layer features pigmented cells that
provide most of the yellow, red, and brown patterning. By pulling out and
pushing in different muscles, the cuttlefish can display various groups of
pigmented cells. A deeper layer of iridescent reflecting cells in blue, green,
red, and pink, as well as a white base, complete the palette.
"Kings of Camouflage"
also showcases several other kinds of cuttlefish, including a tiny species
called the Flamboyant cuttlefish. The size of an egg, it walks on the seafloor
rather than swims. And then there are the amazing Giant Australian cuttlefish, which come together to breed off the
south coast of Australia every autumn.
One of the most amazing displays of
the Giant cuttlefish proves that they have plenty of brains and not just brawn.
Small males, who cannot compete physically with
their larger counterparts, have developed a cunning way to sneak in and mate
with their desired female, by "dressing" as a female cuttlefish.
They pull in their arms, change their colors to a mottled pattern, and glide by
the larger males. Once this female mimic swims underneath and finds the female,
he often as not successfully mates with her. (See Mating Trickery for other
animals that practice crafty courtship.)
Cuttlefish go through only one of
these mating cycles—they burn bright and die young, usually between 18
months and two years of age. With such a short life span, it is even more
surprising that they are so intelligent. Jean Boal of Millersville University
in Pennsylvania shows viewers how much, and how fast, cuttlefish can learn (see
her interview). Boal creates a special enclosure to assess the
cuttlefish's ability to figure out the right escape route. As it turns
out, her cuttlefish are able to learn
the rules of finding the open exit, and repeat their success trial after
trial—yet another example of the smarts of this beguiling creature.
Program Transcript
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