Armadillos, whose name translates from Spanish as “little armored ones,” are instantly recognizable by the bony plates that cover their bodies like a suit of armor. This unique feature often leads people to question their ability to navigate water. Despite the weight and density of their carapace, these New World mammals have developed surprising aquatic skills. The most widespread species, the Nine-banded Armadillo, frequently demonstrates an impressive capacity to cross streams and rivers.
Yes, Armadillos Are Swimmers
These mammals are capable and frequent water travelers, utilizing physical adaptations to traverse aquatic environments. The Nine-banded Armadillo, found across the Americas, regularly encounters water bodies in its habitat and has evolved two distinct mechanisms to overcome them. Their need to cross water has played a significant role in their successful expansion into new territories.
The choice of method depends mainly on the width and depth of the water obstacle. For narrow streams, the animal can simply sink and walk across the bottom, while for wider rivers, a surface-level swim is necessary. Water does not act as a barrier to their movement or foraging activities.
The Buoyancy Strategy: Floating Across
When confronting larger bodies of water, the armadillo employs a physiological tactic to achieve positive buoyancy. Since the weight of its armor naturally causes it to sink, the animal must actively compensate for this density. It accomplishes this by gulping air, which is then directed to inflate its stomach and intestines.
This inflated digestive tract acts as a makeshift flotation device, counteracting the weight of the bony plates. Once floating, the armadillo propels itself across the surface using a paddling motion, often with its snout held just above the water line. This strategy allows them to cross rivers too wide to manage by walking underwater, enabling successful long-distance travel and range expansion.
The Submerged Strategy: Walking Underwater
For smaller streams or shallow water, the armadillo sinks to the bottom and walks across the bed. To accomplish this, the animal must first expel the air from its lungs and digestive system to become negatively buoyant. The dense, hard shell that hinders floating now becomes an asset, helping to anchor the animal against the current.
The armadillo possesses the capacity to hold its breath, typically for four to six minutes, while navigating the riverbed. This breath-holding ability, combined with the anchoring effect of its armor, allows for an efficient underwater passage. The movement involves a steady, plodding gait along the substrate until the opposite bank is reached.
Why Armadillos Need to Cross Water
The ecological pressures driving these aquatic behaviors are linked to the armadillo’s survival. Crossing water allows these animals to expand their territory and reach new areas rich in food resources. They are insectivores that rely on finding insects and grubs.
Waterways also act as natural features that must be navigated when fleeing from predators like coyotes or bobcats. The ability to quickly enter a stream and use either the floating or submerged method provides a reliable escape route. This adaptation has been a significant factor in the Nine-banded Armadillo’s continuous northward migration and colonization of new regions over the last century.