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Species
Basic Characteristics of a Mammal
Mammals are characterized by having hair, a characteristic as
diagnostic as the feather of birds. Hair insulates to help the
animal maintain a warm and constant body temperature making mammals
'endothermic'.
Their active metabolism is supported by an efficient respiratory
system that uses a sheet of muscle called the diaphragm to help
ventilate the lungs. The four-chambered heart of a mammal prevents
the mixing of oxygen-rich blood with oxygen-poor blood.
Mammals as Learners
Mammals have larger brains than other vertebrates of equivalent
size, and seem to be the most capable learners. The relatively
long duration of parental care extends the time for parents to
teach important skills to their young.
Reproduction
Mammary glands that produce milk are as distinctively mammalian
as hair. All mammalian mothers nourish their babies with milk,
a balanced diet rich in fats, sugars, proteins, minerals, and
vitamins.
Most mammals bear their young live. Fertilization is internal,
and the egg develops into an embryo within the uterus of the female
reproductive tract. In placental mammals, the lining of the mother's
uterus and membranes arising from the embryo collectively form
a placenta, where nutrients diffuse into the embryo's blood.
Teeth
Differentiation of teeth is another important mammalian
trait. Whereas the teeth of reptiles are generally conical and
uniform is size, the teeth of most mammal species come in a variety
of sizes and shapes adapted for chewing many kinds of foods. Our
own dentition, for example, comprises a mixture of incisors modified
for cutting, and grinding teeth (molars) specialized for crushing.
Endangered Species
We will be examining several different species of rare mammals
that inhabit that Thompson-Okanagan region of southern British
Columbia:
One of these species is a member of the Rodentia Order. Rodents
are characterized as possessing chisel-like, continuously growing
incisor teeth. Examples of Rodents include: squirrels, beavers,
rats, porcupines and mice.
A species that is vulnerable in the Thompson-Okanagan region is
the Western Harvest Mouse (Reithrodontomys megalotis).
Another rare interior species belongs to the group that are the
only true flying mammals, bats. Scientists classify bats in the
Order Chiroptera, meaning "handwing". The wings, thin
double membranes of strong and elastic skin, stretch across elongated
fingers to body and legs to provide excellent maneuverability;
bats fly more deftly than many birds.
An example of an endangered species of bat that lives in the Thompson-Okanagan
region is the Pallid Bat (Antrozous pallidus).
Another endangered mammal species found in the Thompson Okanagan
region of southern British Columbia that we will examine more
closely belongs to Order Lagomorpha. Members of this order
possess chisel-like incisors and hind legs that are longer than
front legs and are adapted for jumping. Examples of Lagomorphs
include: hares, pikas and rabbits.
The endangered White-tailed Jackrabbit (Lepus townsendii)
was once an inhabitant of certain parts of the dry interior ecosystem
of British Columbia but is now believed to be extirpated. this section sponsored by: |
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