August-September 2024 • Nebraskaland 23
Quills
Quills are a type of modifi ed hair armor-plated in sheaths
of keratin. While they're not "shot" from the animal like
urban legend might claim, quills do often possess irritating
backward-facing barbules near the tip that ensure diffi cult
removal from the skin of a would-be predator. Nebraska's
sole quill-wearer, the North American porcupine, has quills
approximately the diameter of an 18-gauge hypodermic
needle, but only requires half the amount of force to break
the skin barrier than said needle.
A fi ne protective coat, animals also use quills to send a
message of warning. This is known as aposematism, or
deterring predators with color or body coverings. Flaring
them wide or rattling them together, a porcupine can deter
an animal it deems a threat in an intimidating display. Often,
the quills used in this acoustic form of aposematism are
hollow for enhanced noise-making, such as those on African
species of porcupines.
It's important to note that quills are diff erent from
another pokey accessory — spines. Quills are a type of spine
that fall out easily and have diff erent shapes and lengths
depending on where they are located on the body. "Spine" is a
generalized term for any hardened, keratinized modifi ed hair,
encompassing even those that are deeply embedded into an
animal body — such as with the hedgehog. Both of these
spines evolved separately in diff erent species and are thus an
example of convergent evolution.
Convergent evolution happens when animals that are
not closely related, such as porcupines and hedgehogs, or
do not share a common ancestor, adopt similar features or
characteristics on their bodies to meet a similar need — in
this case, for protection.
But could this "fashion" be fatal? Porcupines climb
trees, and as they are not the most agile of animals, often
While some barbules are "zipped" up tight, others, like that in the tail feather of a ring-necked pheasant, are more softly
interlaced.
While not always seen while swimming or on the ground,
the pastel blue of a blue-winged teal's upper wing coverts
are distinctive in fl ight.
