Characteristics
The Basics | Colour | Fur | Feet | Skull and Teeth
| Recycling: Reingestion | The Senses | Locomotion
Fur
Arctic hares (Lepus arcticus) do not hibernate. Instead,
to survive the Arctic cold they rely on one key physical
characteristic -- their fur -- as well as on special
coping behaviours.
Arctic hares can be active all winter because of the insulating
quality of their fur coat. A short, thick and warm under-fur
is protected by the longer, silky top fur. A hare with fat
for 20% of its body weight could live for 15 days at -24°C
(11°F) on that stored fat alone because of this excellent
insulation.
The time of shedding fur and the moulting patterns vary
with latitude. Not much is known about the moulting pattern
but it has been assumed that the annual moult starts in June.
During his research at Sverdrup Pass on Ellesmere Island
(now in Nunavut), biologist Dr.
David Gray saw hares begin
losing their winter coats in April, when temperatures still
hover around -30°C (-22°F). Nursing females seem
to moult later than other Arctic hares.
The black fur on the ear tips may be a way of keeping the
sensitive ear tips warmer when the sun is shining. Black
ear tips are common to many species of hares.
Feet
The hind feet are padded with a heavy, slightly yellowish
brush of thick and coarse fur. Arctic hares have five toes
with claws on the front feet and four toes with smaller claws
on the hind feet.
Skull and Teeth
Arctic hares have 28 teeth. There are four incisors at the
front of the upper jaw, and on each side, a gap and six grinding
teeth. On the bottom, the two incisors on the front are flanked
on each side by a gap and five grinding teeth. The two larger
incisors on the top are supported and strengthened by two
smaller peg-like incisors behind. This trait is common to
all lagomorphs.
Recycling: Reingestion
The Arctic hare employs the specialized digestive system
of recycling that is common to all members of the hare and
rabbit families. This system is called reingestion or refection.
It allows better utilization of nutrients.
The first stage in the digestion process takes place in
the usual manner in the hare's digestive system. This produces
a soft fecal pellet of partially digested plant material.
The hare eats this soft pellet directly from the anus. The
end result the second time around is a round, hard pellet.
Reingestion of the soft fecal pellets happens during rest
periods. The hard round pellets are passed while the hare
is moving and feeding.
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 The largest of the Arctic hare's digestive organs is the caecum or appendix (on right), which does the initial digesting before recycling. The hare was probably killed by a Gyrfalcon (Falco rusticolus).
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the image in 3D:
