Imagine how much more you could get out of a holiday at
Hadahaa if you didn’t have to sleep. Honeymoons would be 30% longer; you’d be
able to catch a glimpse of every shooting star and gaze at every sunrise or, if
you are as obsessed as me, snorkel throughout the night. Sound unbelievable?
Not so for a dolphin; amazingly all cetaceans have evolved the ability to stay
awake throughout the day and night by sleeping with only half of their brain at
a time. Unlike most of us, they must consciously take each breath which
essentially means they can never completely fall asleep. It’s a useful skill,
and got me thinking about other enviable abilities there are in the underwater
world:
Invisibility
Fancy blending into to
the background in an instant? Then consider life as one of our Hadahaa locals -
the Octopus cyanea.
There are some pretty
impressive disguises out there, but Cephalopods really take the biscuit because
they are not stuck with just one look; they miraculously transform the colour,
pattern and texture of their skin to perfectly match with their surroundings.
Layers of different pigment cells expand or contract upon demand to alter the
balance of colours. On top of that, they have tiny muscles which tighten to form
perky little peaks. And if all else fails, they use their jet propulsion and
disappear with a puff of ink.
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Octopus Images
from Roger Hanlon (hermes.mbl.edu/mrc/hanlon/coloration.html)
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Immortality
Feeling a bit senile?
If you were coral you could simply copy yourself and start again, and why stop
there? Multiply into a colony and continue on for hundreds of years.
Once a year, coral polyps have a
brief sexual outburst, but for the rest of the time they make do with the
realms of asexuality. Genetic clones bud from a parent polyp once it has reached
adult size. A degree of connectivity remains between individuals allowing the sharing
of nutrients and combined structural support.
Glow in the dark
Why waste money on
lighting schemes when you could emit light from within? Glittering microscopic plankton glow with a blue-green
light when disturbed at night.
These little protists and
copepods in the waters around Hadahaa contain a special substance called Luciferin
which produces light in a chemical reaction with oxygen. Although this enchanting habit makes them
more obvious to us, it’s actually a defence mechanism. The sudden flash of
light can confuse predators or cause them to feel vulnerable; like a call to
reinforcements, it alerts even bigger hunters that there’s a potential meal
nearby.
Telepathy
Decisions are hard,
wouldn’t it be nice to instinctively know what everyone else is doing, and
automatically do it too? Then think about trading places with the bait fish who
love schooling around the island at this time of year.
A combination of sight and
acoustic vibrations keep the discipline within schools, allowing all the fishy students
to move, turn and swim with perfect cohesion. Fish prefer to stick with others
about the same size with all of them keeping on average a distance of 0.7 body
lengths apart. There are no leaders of
the group; the ones at the front frequently switch places when they change
direction or scatter then re-group. There are many advantages of schooling; an
obvious example being that hundreds of eyes are on the lookout for danger, or
predators becoming easily confused during a chase, not knowing who to single
out for supper.
