Anatomy Tutorials

What makes a mustelid?

The word “mustelid” or “weasel” may give associations to something slender, smooth and short-legged. While it’s true for some of the more well-known species, properly describing their essence can be a whole different matter, as this is a diverse family of carnivorans and omnivores whose members have adapted to a wide range of niches and environments. This drastically affects the way these animals look and behave, so they don’t really have many traits in common as a result.

To make things more complicated, many of their most striking traits are found in several other families within the order Carnivora in response to various types of evolution, like sharing a similar ecological function or keeping traits from an early ancestor they branched from. That’s not to say they don’t have any unique characteristics that sets them apart!

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The basics:

The anatomy is shaped by curves and gives an even, soft appearance without sharp angles and transitions between body parts. There’s no abdominal tuck like in canids, but a slight potbelly can occur.

Flattened skull with a large braincase and short facial region, elongate from the side and broad on top and from the front. There’s little to no dip where the forehead meets the nose bridge.

Dark brown eyes (not including captive or domesticated varieties) that are widely spaced. All mustelids except badgers and otters have horizontally slit pupils.

Rounded ears that are widely spaced, often low-set. They are stiff and can’t move freely to express emotion, only to the side or lay flat against the sides of the skull.

Short but robust and muscular limbs.

Broad, shovel-shaped paws that always have five, elongate digits for holding and gripping.

 Plantigrade to semi-plantigrade gait, with the entire or half of the sole in contact with the ground. Mustelids don’t walk on their digits, and their heels aren’t placed as high as in felids and canids.

An extremely flexible spine that often gives a “hunchbacked” impression.

(More to come)


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