Last week (November 2nd) was World Numbat Day! How did you celebrate??
I don’t blame you if you missed this holiday – I didn’t know what a numbat was until a few days ago! Let’s discuss them now so we’re all ready to celebrate next year.
Numbats (Myrmecobius fasciatus) are small Australian marsupials. They are, on average, 10.6 inches long (270 millimeters) and weigh between 10 and 26 ounces (283 to 737 grams). While numbats used to live across southern Australia, their numbers have declined significantly since the arrival of European settlers. Today, you can only find natural populations of numbats in two areas in Western Australia.
Part of the challenge for increasing numbat populations is how dependent these animals are on termites for food. If a habitat is too wet or too cold for termites, numbats won’t be able to live there either. Today, numbats and their termite food source are found primarily in eucalypt woodlands. Termites feed on the heartwood of most trees in these woodlands, and numbats eat the termites. The numbats also sleep and nest in these hollowed-out logs.
Marsupial lineage
Numbats are marsupials but aren’t closely related to any living marsupials. One of their closest relatives was the thylacine, aka the Tasmanian tiger. Unfortunately, the thylacine became extinct in the 1900s: the last known captive thylacine died in 1936.
This isolated evolutionary lineage makes numbats one of the more unique marsupials. For instance, they don’t have the typical pouch found in koalas or kangaroos. Instead, the female’s belly has skin folds covered in short, golden hair. After a 14-day gestational period (one of the shortest among all mammals!), the newborn numbats move to their mother’s nipples and entwine themselves with this golden fur. The skin folds then cover the young as they grow older.
The numbat joeys remain attached to their mother’s nipples for the next six months or until they grow too big for their mother to walk. During this time, they grow a downy coat that eventually develops the numbat’s characteristic stripes. Their snouts also elongate: young numbats have significantly shorter noses than adults to get a firm grip on their mother’s nipples.
Termite eaters
Many animals that eat termites have strong claws that break apart termite nests. Not numbats! While they have front claws, they’re too small to successfully break into a termite colony. Instead, numbats rely on a good sense of smell and long, sticky tongues to fuel their termite diet.
Numbats sniff out shallow underground termite galleries, the passageways termites use to go to and from their nest. A numbat’s sense of smell is so strong that it can locate termite galleries as far as 50 millimeters (about 2 inches) below the soil’s surface. Once located, the numbat quickly digs into the gallery with their sharp claws. Then, the numbat sticks its long, thin tongue into the gallery. Sticky saliva coats this tongue, and termites get stuck and are brought to the numbat’s mouth. Fun fact: since numbats don’t chew the termites, they have blunt “pegs” instead of proper teeth in their mouths!
This reliance on termite activity is why numbats are diurnal. Since they can’t break into termite nests, they must hunt when termites are active in their galleries. When the termites stay home, the numbats don’t eat.
Conserving energy
Unfortunately for numbats, termites aren’t a very caloric meal. They solve this by just eating a lot! A typical adult numbat eats about 10% of its body weight daily, or between 15,000 and 20,000 termites (plus any predator ants in the wrong place at the wrong time).
Numbats have evolved a few strategies to conserve energy. For instance, they’re only active for a few hours in the winter, matching their time out of the nest with the period when the termites will be active. This helps them not waste energy searching for nonexistent termites and helps keep them hidden from predators.
Numbats have also evolved special fur that effectively traps the heat from sunlight. This lets them stay warm from the sun instead of wasting energy creating their own warmth. Unfortunately, this strategy makes numbats vulnerable to climate change. Research shows that numbats can overheat in just 10 minutes of direct sunlight. While other animals can adapt to rising global temperatures by becoming active during the coolest parts of the day, numbats can’t because they depend on termite activity to feed. If temperatures continue rising, the foraging window for numbats will shrink.
As the world changes, we’ll have to see what happens to these endangered marsupials.
Resources
Leave a Reply