This
will be the first of many species-specific blogs. I always loved giving ‘Animal of the Week’ presentations
for OU Wildlife Club and writing species accounts for classes in
undergrad. Seeing a species I had
previously only read about and seen in pictures gives me great joy and
excitement. In a way it is analogous to
what meeting a celebrity would feel like!
The world is amazingly diverse, in so many ways and through so many
different lifeforms. My blog posts will
in no way begin to tap into the sheer diversity of any given group, but
hopefully they will be fun little posts with interesting factoids about various
species. Every species has its own
unique and often surprising characteristics.
To start this blog type, I’ve chosen one of the stranger members of
class Mammalia: the Nine-banded Armadillo (Dasypus
novemcinctus).
All my sightings
of the Nine-banded Armadillo (from this point on in the text for simplicity’s
sake I will just refer to them as armadillos) in the wild have been in Texas; a
map of their full range is shown below, but this is the only species of
armadillo that includes the US in its range (the rest inhabit South America
only). As reflected by their range, they
are not tolerant of low temperatures and are uncommon in areas with more than
24 days below freezing per year. Within
this range, they are primarily found in forested areas, but can also be found
in scrubby, brushy areas and even less frequently grasslands near forests. This has much to do with diet and foraging
habits; armadillos will sift through leaf litter for invertebrates (which make
up a majority of their diet). They have
a keen sense of smell and are able to smell invertebrates as much as 20
centimeters below ground! It is easy to
see how they rely much more heavily on olfaction, as they have very small eyes (and
poor eyesight) and are crepuscular and nocturnal. I am skeptical of their hearing as well, as I
have walked up to them many times now with them seemingly unaware until I clapped
or spoke loudly!
Armadillo foraging in leaf litter at Gus Engling Wildlife Management Area.
Armadillos
are fossorial; they are adapted to a burrowing and digging lifestyle. This can be seen by their robust limbs and
long claws. Burrows are typically 1-5
meters in length and are range from a few centimeters to 2 meters below the
surface. Although they do not hibernate,
they are more active in the summer, and sleep as much as 16 hours a day (they
have a low metabolism).
Nine-banded
Armadillos are predators to invertebrates and small vertebrates, but prey to
larger mammals such as Bobcats and Coyotes (I found a large piece of central
body armor that had been rolled flat and picked clean in Cooper Lake State
Park, presumably by one of the two previously mentioned species). Raptors will also predate juvenile
armadillos. Unfortunately armadillos are
often roadkill victims (I have also seen this numerous times), but they then
provide food for scavenging species (I have watched Black and Turkey Vultures,
Red-tailed Hawks, and American Crows feasting at these kill sights). They are also important to ecosystems because
their burrows provide homes for other animals such as rabbits, skunks,
Burrowing Owls, and certain snake species.
Armadillo
is a Spanish word meaning “little armored one”.
Taking apart the etymology of their scientific name, Dasypus likely comes from a Greek word
meaning hare or rabbit, because Aztecs referred to this animal as the “turtle-rabbit”. Novemcinctus
denotes their nine central armor bands which are discussed below. Their armoring is a predator defense and is
made up of osteoderms (scales/bony plates) covered by extra keratinous skin. The scales are arranged in bands separated by
soft skin for flexibility, although contrary to its stereotype, the Nine-banded
Armadillo cannot roll itself into its shell (only the Brazilian Three-banded
Armadillo (Tolypeutes tricinctus) and
Southern Three-banded Armadillo (Tolypeutes
matacus) can). Also, although the
name is Nine-banded Armadillo, this species can have 7-10 of these bands. This armoring makes up approximately 16% of
an armadillo’s body weight.
The
armadillo’s reproductive system is extremely interesting. A single egg is fertilized, BUT the female
can delay implantation in the uterus for at least four months, and possibly up
to 2 years. Why? It is an adaptation for the female to avoid
the energetic costs of gestation during times of stress. Furthermore, once implanted, the zygote
splits into 4 genetically identical embryos.
This is known as monozygotic
polyembryony. The armor of juveniles
is soft at birth. Young will stay in the
burrow for 2-3 weeks and are weaned at 90-140 days.
Armadillos
are members of the family Dasypodidae, which contains 21 species in 8
genera, including the Pink
Fairy Armadillo (Chlamyphorus truncatus), shown below. They are in the order
Cingulata and supraorder Xenarthra. This
group is defined by special articulations called xenarthrous processes (see image below) on their lumbar vertebrae. These are extra processes on the sides of
vertebrae in addition to the front and back (pre- and post-) zygapophyses on typical
vertebrates that fit vertebrae together and stabilize movement. These extra
processes stabilize the spine further, making it more rigid, and may function
to support weight while standing bipedally (which armadillos will do). They also do not have canines and (usually) incisors
and have simple, rootless, cylindrical molars and premolars which lack enamel (see
image below). Other members of Xenarthra
include anteaters and sloths.
Pink Fairy Armadillo
(Images found on Google Images)
Finally, a note on
conservation. Although they are not
endangered, threats to armadillos include involvement in the exotic pet trade
(there will be a later blog about this terrible industry). They were introduced to Florida and are
negatively affecting native species there.
Occasional conflicts with humans are due to armadillo burrow building being
a nuisance to agricultural activities. A
word of caution: don’t try to touch a wild armadillo, they can carry leprosy
and you can contract it by touching them!
However, this makes them useful in medical research on this disease as
well as many other parasites that they harbor.
One last interesting fact:
armadillos will gulp air into their stomachs, making them buoyant. Although they cannot cross large bodies of
water, they will cross small water bodies by actively swimming using this
buoyancy or by walking on the bottom.
I picked this species not only
because I recently was able to take the series of photographs shown below, but
because they are so incredibly unique. I
hope you have found this post interesting and learned many new and fun facts as
I have. If you have any questions on
armadillos, post them below and I will do my best to research them and find an
answer! Also, if I have any of this
information incorrect (Alas, I do not currently have my Mammalogy or
Comparative Vertebrate Anatomy textbooks or free access to most science
articles), please let me know! More
species accounts to come, as well as more posts in general.
Until next time,
Jess
Sources:
