Ornate Horned Frog

Jan 1

Ceratophrys ornata

The ornate horned frog is also known as a "Pacman frog" and referred to as a “mouth with legs” — and it is, appropriately, quite a glutton. It'll eat any prey that fits in its enormous mouth, from insects to lizards to mice to birds to other frogs. It'll even attempt to consume prey larger than itself.

If there ever was a physical manifestation of gluttony, it would be the ornate horned frog. Its body is squat and rotund, its little limbs splay out ineffectually from its mass, and most of its head is a mouth — indeed, it's often referred to as simply "a mouth with legs." Its more formal name calls attention to the horn-like crests above each of its little bulging eyes (easily missed amidst its mouth-dominated head) as well as its ornate colouration; varying spots, streaks, and blotches of green, brown, yellow and red. These patterns might have looked pretty, if they weren't painted onto such an aggressively goofy frog. But the frog isn't here to look good, it's here to eat. And regardless, it spends most of its time buried beneath the ground or hidden under leaf litter, practically invisible.

Big Appetite, Little Effort

Strewn across the ground of grasslands and tropical forests, these frogs lay about like so many hidden cowpats. You needn't worry about stepping on one unless you happen to live in southeastern South America, since the species is only found in eastern Argentina, along Uruguay's coast and in southern Brazil. And the closer you are to some form of water, such as a ditch, the higher the concentration of frogs. To us larger animals, the horned frogs are just little ground gremlins; only some 15 centimetres (5.5 in) long, harmless (mostly, we'll get to that later) and somewhat comical. To smaller critters, these frogs are fatal booby traps, sprung via proximity sensors.

The ornate horned frog is a "sit-and-wait" predator, in that it sits motionless and hidden until something happens to wander too close, whereupon the frog bounds forward, its vast maw agape, ready to consume. "Something," in this case, means practically anything that the frog can feasibly fit in its enormous mouth. This includes invertebrates (like locusts and spiders), lizards, mice, birds, and even other frogs — perhaps especially other frogs, as one survey in Uruguay, which analysed the stomach contents of 34 of these frogs, found that 78.5% of their "stomach stuff" consisted of other anurans. But a glutton's appetite knows no bounds and the appetite of the ornate horned frog is voracious, with eyes often bigger than its stomach. But the real problem arises when its prospective meal is also bigger than its stomach. So insatiable is this "mouth with legs" that it'll occasionally attempt to swallow prey that's as big as itself or even larger — likely to no profitable outcome, and possibly some annoyed retribution from the chomped victim. One could call this frog's method of hunting lazy, the frog might call it "economical."¹

Born Wriggling and Screaming

The ornate horned frog is sedentary for most of its life, and it takes its dedication to inactivity even further during autumn and winter when it burrows down into the ground and creates a cocoon around itself to prevent water loss. It remains this way until spring, during which time pouring rains create scattered pools of water — nurseries for spawning new frogs.

Ornate horned frog tadpoles in different stages of development.

A single female can lay up to 2,000 gelatinous eggs in one of these pools, and since the pools are temporary, the young are on a timer. The eggs hatch after a few weeks into thousands of wriggling tadpoles. They develop quickly, beginning to grow in their lungs after only three days. These little lungs allow the tadpoles to do something that's never before been recorded in any other tadpole, or vertebrate larvae of any kind; they can scream. More accurately, they make brief, metallic-sounding alarm calls when distressed — able to do so both in and out of water — likely as a kind of warning system to the other nearby tadpoles. Or at least tadpoles of their own species. Other species of tadpole often end up as food — the horned frog is born rapacious, but seemingly not cannibalistic for its own kind. Under good conditions, the horned frog tadpoles will metamorphose in just two weeks, leave their shrinking pools, and find a hiding spot where they can feed to their stomachs' content.

Ravenous Roommates

Looks are very subjective, but it's fair to say this frog isn't especially handsome (a prince might have a hard time getting a kiss if he was turned into a mouthy horned frog). But at least a few people find the frog charming. Its disproportionate anatomy and empty-headed stare can be kind of cute. And so, for better or worse, it has found its way into people's homes as a pet. It is kept in terrariums with enough foliage for its hiding habit, misted regularly to remain moist, and fed abundantly — although not too abundantly, as heavy rodent-based diets can cause obesity — using a pair of forceps to avoid being bitten by its vomerine teeth (two rough bumps growing out of the frog's upper jaw bone). You can expect your hungry companion to be with you for around 6 years on average, but, if you're lucky, your frog friend can live for upwards of 16 years.

The pet trade is made up primarily of captive-bred specimens. This is for the best, since the wild population of ornate horned frogs was listed as 'near threatened' in 2004 by the IUCN and has remained so as of the last assessment in 2021, with numbers decreasing. Although a few wild frogs are still stolen for the pet trade and some are purposefully killed — unjustly persecuted under the assumption that they're venomous (they're not) — the major threats to the species are less personal and more depressing; habitat loss to agriculture and housing developments, as well as water and soil pollution from agriculture, industry and human settlements.

Pacman Frogs

The ornate frog (also known as the Argentine horned frog, after its locality) is just one of eight species of South American horned frogs in the genus Ceratophrys — collectively known as "Pacman frogs" for their round bodies and big mouths. None are bright yellow, however. Most, like the ornate frog, are painted in varying psychedelic patterns of green, orange, and brown splotches. The Amazonian horned frog is probably the most distinct of the group, with an especially spiky body that, when flattened and half buried in the soil, appears like a fusion of a whoopee cushion and a pincushion.² All eight Pacman frogs are united by cavernous mouths, that are at once off-putting and oddly endearing. One can imagine that, throughout the frogs' evolutionary history, their hunger escalated into gluttony, and their mouths expanded to keep pace with their voracious appetites.

An Amazonian horned frog (*Ceratophrys cornuta*).

A Venezuelan horned frog (*Ceratophrys calcarata*).

A Brazilian horned frog (*Ceratophrys aurita*).

A Pacific horned frog (*Ceratophrys stolzmanni*).

¹ The ornate horned frog is unlikely to have anything to say about anything. In other words, this frog is kind of stupid.

Now, I don't like throwing that term around, since intelligence is relative and it's silly to judge such a different creature as a frog using our human definition of intelligence. But if we were to rank animals based on what we consider "smart," this frog would fall on a pretty low tier. Frogs in general aren't the brightest. Unlike crafty crows or hoarding squirrels, frogs don't have to contend with complex social interactions or tasks that require great memory. They simply don't need those things to survive and thrive, so it would be a waste of their energy to evolve such brainy abilities.

Active hunters appear to be the smartest among frogs since they need brains capable of competently navigating three-dimensional environments, coordinating their own movements and making quick decisions, as well as detecting or tracking prey. Ambush predators, like the ornate horned frog, don't need to be very good at all of that. To acquire food, all they really have to do is react quickly to moving things in their proximity — maybe also judge what's feasibly edible and not, although the horned frog doesn't seem great at that.

² The tadpoles of the Amazonian horned frog are known to be particularly vicious. While the adult version lacks the vomerine teeth which have sent a few ornate frog owners to the hospital, the Amazonian tadpoles possess "highly keratinized mouthparts" — rows of teeth and a beak, which they use to facilitate their diet of, primarily, other tadpoles.

**Where Does It Live?**

⛰️ In grasslands near water, tropical forest floors, and roadside ditches.
📍 Argentina, Uruguay, and southern Brazil.

‘Near Threatened’ as of 28 January, 2021.

IUCN

Size // Small
Length // 11.5 cm (4.5) males and 16.5 cm (6.5 in) females
Weight // Up to 480 g (1 lb)
Activity: Diurnal ☀️
Lifestyle: Solitary 👤
Lifespan: 6 years (on average), up to 16 years (in captivity)
Diet: Carnivore
Favorite Food: Anything that lives and breathes
Class: Amphibia
Order: Anura
Family: Ceratophryidae
Genus: Ceratophrys
Species: C. ornata

The ornate horned frog is a 'sit-and-wait' ambush predator. It squats — hidden beneath soil or leaf litter — until a victim wanders too close. The frog then springs forward, its cavernous mouth open to engulf its prey.

It will eat anything from invertebrates (like locusts and spiders) to lizards, mice, birds, and even other frogs — with one study in Uruguay finding that 78.5% of the frog's stomach contents were made up of other anurans.

Sometimes, this frog's eyes are larger than its stomach (metaphorically, of course, since its actual eyes are quite small, crowned with its eponymous horn-like crests). It's been known to attempt swallowing prey as large as, or even larger, than its own body.

The ornate horned frog lazes about like a slimy whoopee cushion across grasslands and tropical forests, most often near water — at home in Argentina, as well as parts of Uruguay and southern Brazil.

During autumn and winter, the frog burrows down into the ground and creates a cocoon around itself to prevent water loss, emerging again with the spring rains.

Abundant rains create pools of water that become temporary nurseries for horned frog tadpoles. A single female can lay up to 2,000 eggs that, after a few weeks, hatch into thousands of young with a habit of voraciously eating the tadpoles of other frog species.

After only three days, tadpoles develop lungs which allow them to do something that's never before been recorded in any other tadpole, or vertebrate larvae of any kind; they can make brief, metallic-sounding alarm calls when distressed. These vocalisations likely serve to warn other nearby tadpoles of danger.

The ornate horned frog is a somewhat popular pet species — with most of the pet trade consisting of captive-bred frogs. It's important to feed the frog enough, but not too much — not too many rodents, or it tends to become obese — and to keep fingers away from its mouth, the roof of which has a pair of rough-textured teeth.

In the wild, this frog usually lives around 6 years but, with proper care in captivity, it can become as old as 16.