Many cat owners have observed a small fold of skin on the outer edge of their feline companion’s ear. This distinct feature can resemble a small slit or pouch, leading to curiosity about its purpose. It is a common and normal characteristic, yet its exact function often remains a mystery.
Unveiling the Mysterious Ear Pocket
This ear pocket is formally known as the cutaneous marginal pouch, more commonly called Henry’s pocket. It appears as a small, vertical indentation or flap on the lower, outer edge of the cat’s triangular outer ear, the pinna. This fold of skin creates a small pouch near the base of the ear, close to the skull.
The pinna is composed of cartilage covered by skin and fur; the cutaneous marginal pouch extends from this structure. It is a soft, pliable area that can sometimes appear as a minor tear. Its tissue makeup is consistent with the rest of the outer ear.
The Pocket’s Crucial Purpose
While Henry’s pocket’s precise function is not definitively established, theories propose its role relates to a cat’s exceptional hearing. One hypothesis suggests it aids in detecting and amplifying high-frequency sounds. Cats perceive sounds up to 85 kHz, significantly higher than the human range of 20 kHz. This sensitivity benefits hunting small prey like rodents, which emit high-pitched vocalizations.
The pouch may help filter out lower-pitched background noises, allowing higher frequencies to be clearly received and amplified. This could prioritize sounds of potential prey. Another theory suggests the pocket contributes to the ear’s flexibility and movement. Cats have 32 muscles in each ear, enabling them to rotate their pinnae independently by up to 180 degrees to pinpoint sound sources. The pocket might facilitate this articulation, enhancing sound localization and allowing for more expressive ear movements.
Beyond the Feline Ear
The cutaneous marginal pouch is not exclusive to cats; similar structures are found in other mammals. This feature is present in some dog breeds, bats, weasels, and foxes, including the Fennec fox.
The widespread occurrence of this pouch across different species, particularly those with acute hearing, suggests it is a conserved evolutionary feature. While its prominence may vary, its presence in diverse animal groups indicates a potential, not fully understood, biological significance beyond felines.