Biology Reference
In-Depth Information
Despite these differences, weasel family members share at least three major traits in addition to the
fact that they are all carnivores. For one thing, they all have anal scent glands that can emit very un-
pleasant odors. The skunk has made a fine art out of this attribute, converting it into a potent defensive
weapon, but other family members have equally unpleasant scents, though they lack the skunk's scent
volume and efficient distribution system.
For another, most weasel family members utilize something known as delayed implantation in their
reproductive cycles. This means that the fertilized egg doesn't attach to the wall of the uterus and begin
to grow until months after breeding, and only a relatively short time before birth. Delayed implantation
offers some major advantages, which will be explored more fully in the section dealing with weasels
proper.
A third characteristic of the weasel family is a common gait that results in what might be called the
two-step. In this method of locomotion, the tracks of front and hind feet are superimposed. The result
is a track that looks as if it were made by two feet rather than four, one slightly to the rear of the other.
Although some weasel family members use other gaits as well, this one is so typical that anyone who
follows mustelid tracks very far is almost certain to see this distinctive pattern.
With these shared traits in mind, let's examine the unique qualities of the various weasel family
members, for, despite the similarities, the differences between these creatures are striking. The weasel
family is relatively old as mammals go; fossils of weasel ancestors at least 40 million years old have
been found. In the immense interval since, evolution has worked its wonders. Form and function have
become inseparable, so that the highly diverse shapes and sizes of the weasel clan are matched by the
equally diverse ecological niches they occupy.
THE FISHER
As already noted, the name “fisher cat” is a widely used and wholly inappropriate name for the fisher
(Martes pennanti). Although its glossy, dark brown outer fur looks almost black at a distance, and its
tail is moderately bushy like that of some cats, it's hard to fathom why this large, forest-dwelling weasel
has been associated with the feline race. Although proportionally thicker in the body than the super-
slender weasel, the fisher is nonetheless elongated, short-legged, and possessed of a pointed, weaselish
snout that looks anything but catlike. Likewise, the fisher's bounding gait hardly resembles that of a
cat.
Even its correct name—fisher—is extremely misleading. Fishers certainly don't pursue live fish, nor
would they be apt to eat fish at all except through the lucky—and infrequent—circumstance of finding
a dead one. Whence the name, then?
In Old French, the polecat or fitchew—a European weasel relative—was called fissel, later fissau.
This was gradually transmuted in English to fitcher and ficher. Ultimately, the term fitch was applied
to the ferret, which is a domesticated strain of the polecat. The reasonable assumption is that European
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