In the lush, dangerous ecosystem of the Amazon River, the Painted Jaguar serves as the primary predator. When common prey like deer, monkeys, frogs, and beetles become scarce, the Jaguar turns to his mother for guidance on alternative food sources. She suggests targeting the Stickly Prickly Hedgehog and the Slow and Solid Tortoise. Her instructions are specific: to eat the tortoise, one must "scoop him out of his shell," and to handle the hedgehog, one must be cautious of its defenses.
When the Painted Jaguar finally encounters the two friends, they employ clever deception to survive. As the Jaguar demands to know "which one of you is a hedgehog and which one of you is a tortoise," the pair engages in a masterclass of gaslighting. They offer contradictory advice, suggesting complex and nonsensical methods of capture, such as "scooping him out of the water" or "dropping him on his shell." This confusion makes the Jaguar feel that his "spots ache" and leaves him completely disoriented regarding his mother’s original instructions.
The Jaguar’s attempts to capture the pair fail miserably. When he reaches for the Stickly Prickly Hedgehog, he is met with a painful sting, leaving his "paw full of prickles." When he turns to the Slow and Solid Tortoise, he is tricked into throwing the creature into the river, allowing the tortoise to swim away to safety.
Realizing they need a more permanent solution, the friends begin a process of mutual education. The Tortoise teaches the Hedgehog how to swim, while the Hedgehog helps the Tortoise loosen his "back shell plates" to achieve a defensive curl. Through this practice, they undergo a physical metamorphosis: the Tortoise’s plates begin to "overlap," and the Hedgehog’s prickles start to "blend together." By mimicking each other's traits, they effectively disguise their true identities.
When the two friends return to confront the Painted Jaguar, they have become unrecognizable. They approach him with confidence, and when the Jaguar attempts to grab them, they "curled themselves up and rolled around" with such agility that the Jaguar’s "eyes turned cartwheels in his head."
Unable to identify these strange creatures, the Jaguar returns to his mother. He describes a creature that is "not exactly a hedgehog" and "not precisely a tortoise." His mother concludes that they shall call this new, hybrid-looking animal an "armadillo." Thus, the story concludes that the "swimming hedgehog with the prickly coat and the curling tortoise with the overlapping shell" gave rise to the armadillo, a testament to the power of cooperation and creative adaptation in the face of danger.