Humans have five senses, first assigned by philosopher Aristotle: sight, hearing, smell, touch, and taste. But the list is much longer when it comes to senses across species. We’re not talking about paranormal abilities often associated with the term “sixth sense”; instead, these are extra senses humans don’t possess.
These senses include echolocation and magnetoreception, which we can observe and research across several species. A significant number of animals possess a sixth sense; here are six of the most unique abilities in the animal kingdom.
1. Spiders Have a Special Organ
Spiders possess unique organs, known as slit sensilla, which allow them to sense even the slightest mechanical strains to their exoskeleton. These mechanoreceptors provide the spider with information about the mechanical features in their internal and external environment, making it easy for them to judge characteristics such as the size and weight of creatures caught in their webs.
While these arachnids use a range of senses for prey detection, including chemical signals and vision, their mechanosensory system is advantageous as they await the web vibrations that signal approaching prey. And this sixth sense can also help a spider to differentiate between the movements of insects compared to other external elements such as a blade of grass or a gust of wind.
2. How Sea Turtles Navigate the World Using Earth’s Magnetic Map
Sea turtles can pinpoint their ocean location and find their way back to their eggs thanks to an impressive geomagnetic sense. In addition, leatherback turtles possess a pineal gland on the head, allowing them to sense the changing seasons from deep within the ocean.
A study published in Current Biology demonstrated the importance of geomagnetic signatures of nesting beaches in predicting the population structure of sea turtles. This evidence backs the hypothesis for geomagnetic imprinting in these sea creatures. A turtle’s sixth sense allows it to find its way back to its birth area, even decades later. The study suggests that they return to sites within a 50-mile radius of their birth zone thanks to the distinct magnetic signature.
3. Comb Jellyfish Have Receptors to Maintain Balance
Despite its name, the comb jellyfish is not related to jellyfish. What’s more, this ancient creature is at least 500 million years old. Composed of 95% water, the comb jellyfish has no bones or muscles, making it easy to float around in the water. Because of this structure, they have no stomach, lungs, intestines, arms, eyes, or central nervous system.
Still, the comb jelly manages to travel thousands of miles around the ocean, using a special group of receptors called statocysts, which aid in balance and allow the creature to orient itself and remain upright. To find food, the comb jelly uses its receptors to detect chemical changes in the water, which alerts it to the presence of something edible nearby. Their diet primarily consists of zooplankton, plankton, small fish, and crustaceans, but they will eat other comb jellies, if necessary, by biting chunks off them with special cilia in the mouth.
4. Dolphins Rely on Echolocation to Hunt
Dolphins have a fantastic sense of sight, possessing acute visual abilities in and out of the water via a double-slit pupil. Still, their sixth sense provides further assistance to help these intelligent animals find food.
Echolocation is a way of seeing by using sound. When dolphins echolocate, they make short, broad-spectrum pulses that emanate what sounds like clicking to humans. These clicks reflect from ocean objects into the dolphin’s acoustic window, which is sent to the brain for interpretation. This sixth sense helps the dolphin to determine whether approaching creatures are friends or foes, as well as assisting them in the hunt for their next meal.
5. Sharks Use Electroreception to Navigate the Oceans
When it comes to vision, sharks are almost blind; if you look at a shark, you’ll see how small its eyes are compared to the head. And this is why they rely on a sixth sense to help interpret the world around them.
Electroreception allows sharks to detect electrical fields in their environment via tubes termed “ampullae of Lorenzini.” This sense is unique to water-based animals as it requires salty H2O to be effective. In the same way that batteries exert charges, so does saltwater, thanks to the sodium and chlorine ions within it. In addition, fish and other organisms produce small electrical charges when their bodies contract.
Sharks possess around 1,500 ampullae of Lorenzini, the tiny pores that facilitate this fascinating ability, which trigger neurotransmitters to communicate messages to the brain. This sense is so refined that a shark could detect two AA batteries connected up to 1,000 miles away.
6. Bats Have Multiple Unique Adaptations
Bats don’t just have a sixth sense; these flying mammals have a sixth, seventh, and eighth sense. Famed for their echolocation powers, bats possess a larynx (voice box) capable of creating an ultrasonic buzz, which the bat can then emit from their nose or mouth. As the sound waves travel and come into contact with other objects, they bounce back to the bat, providing them with information about their surroundings.
In addition, bats have a geomagnetic sense similar to turtles, which they also use for migration; they can detect even the weakest magnetic fields. The final sense, which completes the bat’s trifecta of special abilities, is polarization vision. This skill enables a bat to sense the sun’s pattern even if it’s set or is obscured by clouds. While this is a relatively recent discovery, scientists think that bats probably use it in conjunction with their geomagnetic sense to help them navigate.
