“…and today we’re talking about a dessert demon. But more on that later.”
Finding a solid food source is a top priority in the red dust of the Australian outback. But one thorny little devil has developed an appetite for the dessert’s spicy buffet. Not all creatures can stomach one of nature’s most common prey animals–but this little armored lizard can sit back and let the snacks come to him in Life, Death, and Taxonomy.
Description
- Looks like a tiny, armored dinosaur that got lost in a cactus patch
- Covered in hard, spiky scales in a mix of yellow, red, and brown, blending into the desert like a grumpy chameleon
- Rough, almost sandpaper-like skin texture that screams “don’t touch me”
- Small, compact body compared to other lizards, like a pint-sized tank
- Has a weird “false head” on its neck to fool predators into biting the wrong end
- Short, stubby tail that doesn’t do much but sit there looking prickly
Measure Up
Welcome to the beloved Measure Up segment. The official listener’s favorite part of the show! The part of the show when we present the animal’s size and dimension in relatable terms through a quiz that’s fun for the whole family. It’s also the part of the show that’s introduced by you when you send in audio of yourself saying, singing, or chittering the words Measure Up into ldtaxonomy at gmail dot com.
Length of the Thorny Devil
Adults typically measure 15–20 cm (6–8 inches) from snout to tail tip. Females are generally slightly larger than males.
a) The length of a spinifex grass blade
A blade of spinifex grass (Triodia spp.), a dominant plant in the Thorny Devil’s desert habitat, measures about 15 cm (0.15 meters or 5.91 inches) long for a mature blade, per botanical records.
b) The length of a Pitjantjatjara spearhead
A traditional Pitjantjatjara spearhead, used by Indigenous people in central Australia, measures about 30 cm (0.3 meters or 11.81 inches) long, based on ethnographic data.
c) The length of a bilby’s tail
The tail of a greater bilby (Macrotis lagotis), a marsupial sharing the Thorny Devil’s desert habitat, measures about 20 cm (0.2 meters or 7.87 inches) long, per wildlife data.
Question: How many fit into each length comparison?
A) 2.1 spinifex grass blades go into the length of a Thorny Devil
B) 1.5 Thorny Devils go into the length of a Pitjantjatjara spearhead
C) 0.5 bilby tails go into the length of a Thorny Devil
Weight of the Thorny Devil
They weigh approximately 30–90 grams (1–3 ounces), with females often heavier, especially when gravid (carrying eggs).
a) The weight of an emu feather
A single emu feather (Dromaius novaehollandiae), from Australia’s outback, weighs about 5 grams (0.005 kg or 0.176 ounces), per wildlife estimates.
b) The weight of an Uluru rock sample
A small rock sample from Uluru, a cultural and geological landmark in central Australia, weighs about 500 grams (0.5 kg or 17.64 ounces) for a hand-sized piece, per geological records.
c) The weight of a desert quandong fruit
A desert quandong fruit (Santalum acuminatum), a bush food in the Thorny Devil’s range, weighs about 15 grams (0.015 kg or 0.529 ounces), per botanical data.
Question: How many fit into each weight comparison?
A) 17.0 emu feathers go into the weight of a Thorny Devil
B) 4.9 Thorny Devils go into the weight of an Uluru rock sample
C) 3.7 desert quandong fruits go into the weight of a Thorny Devil
Fast Facts
- Range: Found only in the arid deserts and scrublands of central and western Australia.
- Habitat: Lives in sandy or rocky deserts, often hiding among spinifex grass or burrowing slightly to stay cool.
- Mating Behavior: Males fight for females by head-bobbing and tail-lashing, with mating occurring in late winter to early spring.
- Hunting Behavior: Sits and waits for prey to pass by, using its sticky tongue to snatch them up.
- Lifespan: Can live up to 20 years in the wild if it avoids becoming a snack.
- Social Behavior: Mostly solitary, only mingling during mating season or when competing for prime ant trails.
- Sounds: Doesn’t vocalize much, but may hiss when threatened, sounding like a tiny, annoyed teakettle.
- Predators: Eaten by birds of prey, snakes, and occasionally goannas (monitor lizards).
- Interesting Fact: Its skin can absorb water like a sponge, channeling moisture from any part of its body to its mouth.
Major Fact
The Thorny Devil (Moloch horridus) is a highly specialized ant-eater, with its diet and feeding behaviors finely tuned to exploit ants as its primary food source.
Dietary Specificity
- Primary Prey: The thorny devil almost exclusively feeds on small black ants, particularly species of the genus Iridomyrmex (commonly known as Argentine or meat ants). Occasionally, it may consume other small ant species, but Iridomyrmex dominates its diet due to their abundance in its desert habitat.
- Quantity: A single thorny devil can consume 2,000–5,000 ants per day, depending on its size, activity level, and environmental conditions. This high volume is necessary because ants are small and provide limited energy per individual.
- Nutritional Adaptation: Ants are low in calories but rich in protein and certain nutrients. The thorny devil’s metabolism is adapted to process this low-energy, high-volume diet efficiently, with a slow metabolic rate suited to its desert lifestyle.
Feeding Behavior
- Foraging Strategy: Thorny devils locate ant trails, where ants move in organized lines to and from their nests. They position themselves near or over these trails, remaining stationary or moving slowly to avoid detection by predators.
- Tongue Mechanics: They use a short, sticky tongue to flick ants into their mouth one at a time with remarkable precision. This rapid, repetitive action allows them to consume hundreds of ants in a single feeding session, which can last hours.
- Selective Feeding: It targets smaller ants, avoiding larger insects or those with strong defenses (e.g., biting or stinging).
Anatomical and Physiological Adaptations
- Mouth and Jaw Structure: The thorny devil’s small mouth and specialized jaw are optimized for picking up tiny ants. Its teeth are minimal, as chewing is unnecessary for such small prey.
- Digestive System: Its digestive tract is adapted to process large quantities of chitin (the hard exoskeleton of ants), extracting nutrients efficiently. The stomach and intestines are relatively simple but effective for breaking down small, protein-rich prey.
- Energy Conservation: The thorny devil’s slow movements and low metabolic rate complement its ant-based diet, allowing it to survive on the limited energy provided by ants while minimizing water and energy loss in the desert.
Ecological Context
- Ant Abundance: The arid regions of Australia support dense populations of Iridomyrmex ants, which form extensive trails and colonies. This reliable food source makes ant specialization viable for the thorny devil, unlike broader diets required by other desert lizards.
- Niche Specialization: By focusing on ants, the thorny devil occupies a specific ecological niche, reducing competition with other insectivorous reptiles that target larger or more varied prey.
- Seasonal Feeding: Feeding activity peaks during warmer months (spring and summer, September–February), when ants are more active. In cooler months, the thorny devil may reduce feeding or enter a state of torpor to conserve energy.
Comparative Perspective
- Unlike generalist lizards (e.g., bearded dragons), which eat a variety of insects, plants, and small vertebrates, the thorny devil’s ant specialization is rare among reptiles. It shares this trait with a few other species, like the Texas horned lizard (Phrynosoma cornutum), which also primarily eats ants but supplements with other insects.
- The thorny devil’s reliance on ants is similar to the dietary specialization of anteaters or aardvarks in mammals, showcasing convergent evolution for exploiting abundant, small prey.
Challenges and Risks
- Dependence on Ant Populations: The thorny devil’s survival is tied to healthy ant populations. Environmental changes, like drought or habitat disruption, could reduce ant numbers, impacting its food supply.
- Energy Trade-Off: Consuming thousands of ants requires time and energy, leaving less time for other activities like mating or predator avoidance. Its slow lifestyle mitigates this but underscores the delicate balance of its specialization.
Fun Fact
- A thorny devil can eat ants at a rate of about 45 ants per minute during peak feeding, showcasing its efficiency as a specialized predator.
Ending
So stay prickly, be patient, and slurp up a line of bugsnax like the thorny devil here in LDT.