Why do cats have little pockets on their ears?

The official name of this small pocket can be translated as cutaneous marginal pouch, but it's commonly referred to as Henry's Pocket. Cute, soft, and mysterious – just like our feline friends.

Now let’s delve into the topic of this eerie little pocket on a cat’s ears.

The mysterious little pocket on the cat’s ears

Cats have 32 muscles in each of their ears, which is almost twice as many as most dogs. This allows them to move their small ears independently from each other. This is a handy feature considering that cats’ ears are specifically designed for channeling sounds. That is, to detect prey or potential threats immediately. Our furry friends can perceive sound waves ranging from 48 Hz to 85 kHz, which researchers believe is one of the widest hearing ranges among mammals.

When we project this onto Henry’s Pocket, it’s not much of a surprise that it’s generally assumed to amplify high-pitched sounds. Specifically, it dampens the lower frequencies. It’s a bit like the pocket separates the two: delaying the lower sounds by bouncing in the pocket. This allows for amplification of the higher frequency sounds potentially produced by prey, whose chirping typically ranges between 22 and 70 kHz.

But who is Henry?

Well, the truth is, nobody knows exactly. Of course, there have been some theories to answer the question, and we’ll share one so your curiosity doesn’t nag at you too much.

Joseph Henry (1797-1878) was a respected American scientist during his time, serving as the first secretary of the Smithsonian Institution. According to britannica.com, his experiments with electricity, magnetism, and sound waves led to breakthroughs. He measured the propagation of sound, the force of gusts, and the heat of sunspots, and even assisted Samuel Morse in developing the telegraph. Consequently, it’s perhaps not so surprising that the “henry,” this elegant frist- and surname, eventually became the unit of inductance after Joseph Henry. Since sound travels in waves, and cat ears along with their associated little pockets aid in amplifying sound waves, some speculate that the pocket was named after Joseph Henry.

Do other animals have Henry’s Pockets?

It occurs in some dogs too, although it’s very rare. Typically, dogs with upward-pointing ears and short fur have this accessory, such as Chihuahuas or Boston Terriers. In the animal kingdom, wild cats, bats, and weasels also boast this feature. We can assume they possess this cute accessory for the same reason, but for sure, nobody knows yet.