“Winter” is the fifth (4th aired in US) episode in the Frozen Planet series about the Earth’s polar regions. Examples of the Aurora Australis (i.e. Southern Ocean) is shown as the episode transitions to featuring the Antarctic, the Finger of Death, and the Emperor Penguins.
Penguins are shown huddling together to keep warm through the winter,
as the only species that remains in Antarctic on the ice throughout the
winter. The Weddell Seals are also briefly shown as the only mammals
that winter in Antarctica. They remain mostly underwater and work to
keep breathing holes open.
The underwater sea life that remain in
Antarctica year round are also featured. Some of the fish have a type
of antifreeze to keep them from freezing. Some of the sea life like
sponges are thousands of years old. These species are often shielded
from the extremes above, but the winter extremes do sometimes affect
them in the form of brinicles. These are ice stalactites that form
quite quickly and the sea life cannot always more away fast enough to
escape the brinicles, which are nicknamed fingers of death.
Weddell Seals are again briefly featured near the end of the episode.
The different sounds they make are played and the seals are shown
fighting over breathing holes.
Winter is shown ending with the
arrival of the sun in the Antarctic and the female Emperor Penguins
returning. Chicks are transferred to their mothers' care, so the males
can go feed in the ocean. Some of the chicks do not make it and the
returning mothers are shown trying to kidnap chicks that wander away
from their mothers.