Page 67 - Oceans

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hUntInG UnDer the Ice > < IcY Waters
Many seals hunt fish and squid Salt seawater freezes at 28.8°F
under the ice, surfacing to (-1.8°C), so it can be colder
breathe at the ice edge. But as than the freezing point of
the Antarctic pack ice expands fresh water. Animals that
north in winter, weddell seals live in the water below the
stay behind, feeding beneath pack ice must cope with
the pack ice. They breathe temperatures that might freeze
through holes that they make their bodies. Many polar fish
in the ice by using their teeth and shellfish survive because
to chip away the ice around they have natural antifreezes
existing cracks. Most weddell in their body fluids. Since food
seals have badly worn teeth is plentiful on the seabed,
as a result, and some die from these animals can live beneath
serious dental infections. the ice in large numbers.

> seaL cOLOnIes
In the Arctic, female seals climb out onto the
ice to give birth to their pups. Harp seals form
large colonies on unstable pack ice, which
cannot support the prowling polar bears that
are their main enemies. Harp seals feed their
white-coated pups on rich milk for just 12 days
before returning to the water.

< BreeDInG PenGUIns < sea Bear
Most Antarctic penguins breed The polar bear is a specialized
on rocky shores in summer, marine predator that lives
choosing places where there on the Arctic sea ice. It preys
is no ice to freeze their eggs. mainly on seals—especially
Many species like this king ringed seal pups in spring—
penguin breed on the islands and follows the edge of the
fringing the Southern Ocean, stable pack ice as it advances
which thaw out for longer and recedes with the seasons.
than the Antarctic continent. When the pack ice breaks up
It supports its egg on its large in summer it is often forced
webbed feet, covering it with to swim to the land. But here
a flap of skin to keep it warm. it has trouble finding food,
Uniquely, the closely related and many polar bears die
emperor penguin uses the of starvation. Its future is
same method to breed on seriously threatened by the
sea ice close to Antarctica, dwindling area of summer sea
incubating its egg thoughout ice in the Arctic caused by
the harsh polar winter. global warming.