In the animal kingdom, the ability to hear is essential to the animal’s survival, and deafness puts that animal at a greater risk to predators. While animals that are deaf can occur in any species, such as from a genetic issue or as a result of trauma, there are little to no species of animals where deafness is a biological trait. There are a few animals, however, that are considered deaf, as well as animals with no ears. Continue reading to learn more about deafness in the animal word.
3 Animals that are Considered Deaf
Scientific Name: Cephalopoda
Cephalopods, such as cuttlefishes, octopuses, and squids, are listed first because, at one time, they were thought to be completely deaf. In fact, an article published in the American Naturalist in 1985 discusses why they assume these creatures are deaf. However, in recent years, studies have shown that cephalopods can actually hear low-frequency sounds.
The confusion with whether or not cephalopods can hear started because, unlike other sea creatures, cephalopods don’t have the gas-filled chamber that lets them hear underwater. Since they are missing this chamber, it was thought that they couldn’t detect the pressure waves of the sound, according to BBC Earth News.
After years of back and forth as to whether or not they can hear, sensory philologists at the Taiwan National Academy of Science found that cephalopods use their statocyst, a sac-like organ, to register sounds.
Naked Mole Rat
Scientific Name: Heterocephalus glaber
These fascinating mammals are nearly deaf because of their outer hair cells, which cannot amplify sound. They have difficulty hearing quite sounds, and can only perceive sound between 0.5 to 4 kilohertz. Naked mole rats are also blind. So how do they go about their daily lives without the ability to see or hear very well?
Their colonies consist of hundreds of naked mole rats, and they use their large numbers to defend their underground tunnels, as well as help find food. An interesting fact about these unusual rats are that they can live up to 30 years.
Scientific Name: Cingulata
Armadillos have an interesting appearance with their armored shell covered in scales. Since their eyesight and hearing is lacking, they use their sense of smell to find food, including as spiders, earthworms, cockroaches, yellow jackets, snails, and scorpions.
While armadillos can provide many benefits, such as natural pest control, they are also considered an annoyance to many people. This is because their digging for food and underground burrows can cause structural damage to homes, as well as damaging gardens and lawns.
What Causes Deafness in Animals?
There are several causes of deafness in the animal community, including trauma and genetic mutations. Animals with white fur, for example, have a higher chance of being deaf than those with other colored fur.
A study conducted by the Feline Health Center at Cornell University found that up to 22 percent of cats with all white fur where born deaf. This amount increased to 40 percent when the cat is born with all white fur and one blue eye. It rises to an astonishing 85 percent if the feline is born with all white fur and two blue eyes.
The cause of the white fur varies and may be due to a breed trait or a genetic issue, such as piebaldism. Piebaldism is a gene mutation that causes an absence of melanin-creating cells. Melanin is a part of the DNA that determines color for skin, eyes, hair, and fur.
These melanin-creating cells also come from the same stem cells that are found inside the inner ear and allow us to hear. So when they are not present, the ability to hear goes right out the window. The piebald gene can occur in a wide array of animals, including cats, dogs, deer, snakes, horses, birds, and cows.
Can Animals be Born Deaf?
There are several animals that are born deaf but develop their hearing as they age. Puppies, for example, are born without the ability to hear, and their hearing doesn’t develop until they are about 3 weeks old. Kittens and squirrels are two other examples of an animal species that are born deaf, but will gain their hearing in the weeks after their birth. The reason for this is because their ear canals are closed when they are born, which prevents the from hearing.
3 types of animals with no ears
Some animal species are actually born without ears. You may think that this would put them in a disadvantage but, despite their lack of ears, they can still hear. Just in a different way than you or I.
Scientific Name: Serpentes
While snakes don’t have external ears, they do have inner ears which sense the vibrations of sound waves. They also do not have an eardrum. Instead, their inner ears connect to the jawbone. When they slither, their jawbone touches the ground, which allows them to sense the vibrations. Very few studies, however, have been conducted to determine whether or not snakes could sense sound vibrations in the air like they do with vibrations on the ground. And the studies that where done typically only looked at one type of snake. Because of this, it is still unclear as to whether or not snakes can sense vibrations in the air.
Scientific Name: Brachyura
While crabs can only “hear” frequencies that are close by and within the low to mid range, they can still hear. Crabs have a statocyst that they use to detect sounds. Their bodies are covered in external sensory hairs, which helps to detect movement and vibrations. Crabs also have the ability to walk in every direction, though they typically walk sideways. The average lifespan of these decapods is about 4 years, but the Japanese Spider Crab (Macrocheira kaempferi) can live up to 100 years.
Scientific Name: Testudines
Turtles don’t have external ears. They instead rely on their internal ears to help them hear. Unfortunately, their hearing on land isn’t as good as other animals, and their hearing improves once they are underwater. When on land, they depend on vibrations and air pressure changes to differentiate between pray and predator. In fact, even dessert turtles ,who don’t encounter many large bodies of water in their lifetime, hear better when under the water, according to a 2012 study.