arms make for better impersonations
have discovered one of the most striking examples of mimicry
in the animal world: an octopus which scares off predators
by changing its appearance selectively to resemble poisonous
for survival - the octopus mimics a sea-snake (above
left) and a poisonous banded sole (above right).
mimicry is common in nature by harmless creatures hoping
to be mistaken for their more dangerous counterparts,
most octopuses alter their appearance to melt into the
background, resembling rocks, coral or drifting plants.
The mimic octopus is the first animal discovered by scientists
which is able to choose selectively from a range of impersonations,
and to respond appropriately to different predators.
Tom Tregenza of the school of biology and colleagues from
Australia were the first to document the mimic octopus,
noticing their astounding behaviour during research dives
travelling at speed, the octopus draws all its arms into
a leaf-shaped wedge and undulates its body, to resemble
a type of sole common to the area. It can also swim above
the sea floor, with arms clearly striped and trailing
from the body, to resemble the poisonous lion-fish. When
attacked by damsel fishes, the octopus threads six of
its arms down a hole, and raises the other two in opposite
directions, creating the appearance of the damsel fishes'
main predator, the banded sea-snake.
Tregenza explains: "The octopus is ideally suited to these
kind of impersonations, as its lack of skeleton allows
for flexible movement, and it has the ability to change
the colour, pattern and shape of its skin. We also saw
the octopus take on other forms that seemed to resemble
sea-anemones and jellyfish. We need to do more research
to find out about these fascinating creatures."
here for further information, and links to a movie of
the sea-snake impersonation