Do Sharks Have Ears? Can They Hear?

If you hear someone say “shark,” what’s the first thing that comes to mind? Is it their razor-sharp teeth or their stoic dorsal fin? Is it how quickly they dart toward the faintest drop of blood? Do you ever wonder what makes them such capable and fast-acting predators in the deep blue sea? It’s not their hearing or sight – their sense of hearing!

With excellent vision, sharks’ eyes see well in almost any light, but their ears fill in the gaps with their incredible sense of hearing. While they don’t have an outer ear, they have a small hole on either side of their head that connects to their inner ear. Despite the lack of outward appearance, shark ears pick up sounds over 800 feet away, giving them a helpful defense from other predators and an easy advantage while hunting.

Sharks aren’t the only sea animals without an outer ear. Most fish only have inner ears. The fish with ears that have the closest structures to sharks are manta rays. The ability to hear is crucial to the health and survival of all sharks, but deep-sea species like the Australian ghost shark have nothing but their hearing to keep them directed toward their prey.

Let’s dive into the ear’s structure and what it means for their hearing.

What Does a Shark’s Ear Look Like?

To find a shark’s ear, look closely along the sides of its head for two small holes. Though they don’t look much, sharks don’t need an outer ear to pick up sounds like a human might. Their ear is entirely internal, only marked by these holes. The inner ear, which features a similar structure to a human ear, picks up all of the sound.

Within the inner ear, there are three canals, which all have a semicircular shape. These bones connect to the same place as the utriculus, sacculus, lagena, and macula neglecta. The first three of these organs are the home of sensory hair cells, which feel the vibrations of sound and do not come in contact with the outer environment. The macula neglecta, on the other hand, connects externally, though it also features the sensory hair cells. Comparatively, humans only have three inner ear bones – the stapes, malleus, and incus.

How Does a Shark Hear?

The layout of the shark’s inner ear directs all sound and balance that they need for survival. Imagine that a sound happens 500 feet away. The vibrations that the sound makes naturally move the water and the shark’s body, but their ear canals also sense the movement. As the vibrations gently pulsate through the water, the stereocilia – or tiny hair cells – also receive the stimulation. Even with small movements or struggles, the stereocilia need little movement and sound to react.

Once the brain interprets this movement, the shark instantly understands how close the noise source is, and they know exactly where to go to find out what caused it. Hearing a small or faraway sound seems difficult, but splashing, struggling, and other distinctive sounds are different from the typical background noise in the ocean, making them stand out from the shark.

While every shark is different, most hear sounds as low as 10Hz or as high as 800Hz. The noises they pick up most easily are low, like the sound of the lowest note on a piano. However, inconsistent noises (like the sound of struggling prey) are enough to attract their attention, telling them that viable prey is near. They sense exactly how far away their prey is by combining their hearing with other senses, which means that sharks never have to worry about their next meal.

How Else Can a Shark “Hear”?

Unlike similar fish, sharks have a sixth “sense” – electromagnetism. Discovered by Adrianus Kalmijn, the scientific community first understood the shark’s ability to sense electromagnetic fields with electro-sensory organs about 50 years ago. This sense gives sharks a greater advantage when locating prey, avoiding bigger threats, or finding a mate. Though they have clear hearing, they use this sense to detect the smallest nanoscopic currents among all of the other white noise in the ocean.

Scientists have different views of what this special ability means for the species. David Julius, Ph.D., a professor and chair of physiology at the University of California – San Francisco, stated that his studies indicated that the smallest changes elicited an “attack now” urge in sharks. Other experts explain that the ability works with the nervous system, controlling the communication between neurotransmitters and nerve cells.

To control this sense, a shark has electrical sensors throughout their body. The sensitivity of these organs is so high that this predator easily hears the heartbeat of any animal – including a human – while underwater. Though this extra sense is helpful, sharks still rely on their hearing to find their next meal.