Page 204 - Atlas Of The World's Strangest Animals

204 ATLAS OF THE WORLD’S STRANGEST ANIMALS

To humans, the ocean can be as challenging and hostile as muscular structure that houses their gills, stomach,
outer space itself.The area covered by our planets’ great reproductive organs – and hearts.
global ocean is vast. Much of this is totally unexplored, but Yes, hearts: octopi have three! Humans, like most
even in its upper regions, life is as strange and as alien as mammals, have red blood because the protein that binds
anything we might discover on other planets. oxygen (haemoglobin) contains iron. The blood of octopi
Octopi belong to a group of invertebrates known as is blue because their oxygen-binding protein comes from
cephalopods and they are one of the ocean’s great oddities. hemocyanin, which is copper-based.This is a poor binder,
The word cephalopod means ‘head-footed’, referring to so to cope with low oxygen levels in their blood, the
the the way that the arms of the octopus attach directly to octopi need three hearts.These help to maintain a
its head. Cephalopods, like molluscs, have an exterior shell constant, high blood pressure.
while cephalods, like cuttlefish, have a small, residual The octopus’ most alien feature, however, is undoubtedly
skeleton. By contrast, the bodies of octopi contain neither its famous arms.These long, flexible structures are their
of these protective structures. Instead their soft, internal main way of interacting with their environment and are
organs are defended by a mantle – an extraordinary, used for everything from hunting to feeding, mating to

Octopi have short and solitary lives, so when they meet to Males produce sperm in packages called spermatophores.A
mate, there is no formal courtship or elaborate display. special arm (the hectocotylus) deposits these into the female.

Once the female decides conditions are right, she lays her The female works tirelessly to clean and aerate her eggs, living
eggs. Now, her sole purpose is to ensure they hatch safely. just long enough to see her young start lives of their own.

(c) 2011 Marshall Cavendish. All Rights Reserved.