The tongue is one of the most versatile organs in the animal kingdom, allowing animals to taste, manipulate food, clean themselves, aid in swallowing, and even communicate. But do all animals have tongues? The quick answer is that most, but not all, animals have some form of a tongue.
In this comprehensive guide, we will explore the intriguing question of whether all animals have tongues. We will examine the key functions of the tongue, compare tongue anatomy across different animal species, highlight some interesting tongueless animals, and recap the main points in a conclusion.
What Are the Main Functions of the Tongue?
The tongue, the muscular organ inside the mouth, performs several critical functions for animals. From tasting food to grooming and swallowing, the agile tongue assists in various day-to-day activities. Let’s explore five of the main functions that make the tongue such a vital body part.
Tasting
The tongue’s numerous taste buds allow animals to detect flavors in potential foods and drinks. Humans have about 10,000 taste buds, whereas cats have only 473. When substances enter the mouth, the taste buds send signals to the brain, helping the animal determine if the item is appetizing or unpalatable.
Manipulating Food
With its flexible muscles and rough surface, the tongue manipulates food inside the mouth, positioning it between the teeth for biting and chewing. Cats, giraffes, and lizards, for example, all use their tongues much like hands to grasp, pull, push, and reposition items.
The tongue also mixes food with saliva to create a bolus that can be swallowed easily.
Grooming
Like a natural hairbrush, the tongue helps certain animals groom themselves by licking fur or feathers to clean and fluff. Cats spend much of their waking hours self-grooming with their bristly tongues.
Anteaters have the longest tongues relative to their body size for accessing hard-to-reach ants and termites within narrow tunnels. Grooming distributes protective oils over the fur and removes dirt or parasites.
Swallowing
With a wave-like motion, the tongue helps move chewed food or liquid to the back of the mouth for swallowing. This peristalsis motion transports the bolus from the oral cavity down through the pharynx and esophagus via involuntary muscle contractions.
The tongue’s movements ease and regulate the swallowing process so animals don’t choke while eating.
Communication
Various animals utilize their tongues for nonverbal communication. Dogs pant with their tongues out to stay cool and indicate happiness or stress. Cattle and chameleons have prehensile tongues they can extend to grasp objects, a useful evolutionary trait.
Many species like snakes use their tongues to pick up scent particles from the air or ground to detect predators or prey. The tongue truly helps some animals express themselves.
Tongue Anatomy Across Species
Mammals
The tongues of most mammals contain similar structures and components. The top surface is covered in small bumps called papillae which contain the taste buds. Underneath lies a layer of muscles that allow the tongue to move freely in different directions.
The base of the tongue is anchored to the hyoid bone. Salivary glands underneath the tongue and in the mouth produce saliva to help moisten food. Mammals like humans, dogs, and cows all have these general tongue features.
However, the size, shape, texture, and agility of the tongue varies between species depending on diet. For example, giraffes have long tongues adapted for grabbing leaves from tall trees.
Birds
Birds have tongues with some similarities and differences compared to mammalian tongues. The top surface contains taste buds and the underside has muscles for movement. However, a bird’s tongue lacks salivary glands. Instead, saliva is secreted from glands in the mouth.
The tongue bones connect to the hyoid apparatus which is more complex and flexible in birds compared to mammals. This allows for a wide range of tongue motions. Bird tongues are adapted for different diets.
For example, nectar-eating hummingbirds have forked extensible tongues for accessing flower nectar whereas insect-eating woodpeckers have longer, spear-like tongues for grabbing prey.
Reptiles and Amphibians
As cold-blooded animals, reptiles and amphibians do not use their tongues for regulating body temperature like mammals. But their tongues still serve important functions like collecting chemicals from the environment to interpret stimuli.
The tongue anatomy in reptiles and amphibians shows greater diversity compared to mammals and birds. Snakes, for example, have a notched, forked tongue which aids in smelling. Some lizards like chameleons have projectile tongues for catching prey. Frogs use their sticky tongues to catch insects.
Salamanders have prehensile tongues for grabbing food. Despite the differences, all reptile and amphibian tongues contain sensory receptors to gather chemical information.
Fish
Fish tongues differ greatly from terrestrial vertebrates. Rather than a fleshy muscular organ, a fish tongue is a small rigid structure made of bone. It lacks taste buds and is not used for manipulating food. The fish tongue is connected to a bone called the basihyal.
Its main function is to help grasp and swallow food by retracting to pull the food into the esophagus. Some fish likeTetraodontiformes can project their tongues for feeding or defense. Fish tongues come in a variety of shapes like thin and splint-like in eels or wide and spoon-shaped in some catfish.
Overall fish tongues serve a limited role compared to other vertebrates.
Invertebrates
Invertebrates like insects, mollusks, and worms do not have fleshy muscular tongues like vertebrates. But some invertebrates have analogous structures that serve similar sensory functions. Insects have a mouthpart called the hypopharynx which helps move food and contains chemoreceptors for taste.
Butterfly and moth proboscis for drinking nectar are also tongue-like. Cephalopods like octopus and squid have radulae—rows of chitinous teeth—for grasping prey. Earthworms do not have specific tongue structures but their mouth cavities contain chemosensory cells for tasting chemicals in the soil when burrowing.
Tongueless Animals
Sea Stars and Urchins
Sea stars and sea urchins are examples of marine animals that do not have tongues. They use their tube feet located on the underside of their bodies to grasp and manipulate food, rather than using a tongue.
Sea stars extrude their stomach to externally digest prey such as bivalves, while sea urchins use their specialized mouthparts known as Aristotle’s lantern to scrape algae off rocks.
Crocodiles and Alligators
Crocodilians including crocodiles and alligators have tongues but they are attached to the floor of their mouths. According to wildlife experts, their tongues are immobile and permanently attached near their throat by a fold of skin and cannot move at all.
So while they technically have tongues, crocodilians cannot use them for tasting, manipulating food or cleaning themselves like other tongued animals can.
Some Birds
Most birds like parrots and hummingbirds have tongues, but some species lack tongues entirely. According to avian biologists, pigeons, ostriches, toucans and mynah birds have no tongues. They use their hardened beaks to manipulate and swallow food instead.
Interestingly, woodpeckers have extremely long tongues that wrap around their skull when retracted to facilitate capturing insects inside holes in tree bark.
Some Fish
Fish tongues differ greatly from terrestrial vertebrates. According to marine biologists at the American Museum of Natural History, over 50% of fish species lack tongues with cartilage and bone instead of muscles and flesh.
However, some fish like salmon and catfish have protrusible tongues with taste buds that help them identify food. The longest tongue relative to body length belongs to the humphead wrasse which uses it to swallow prey over twice its body length.
Some Insects and Spiders
Insects and spiders do not have tongues like mammals. According to entomologists, while butterflies have a long protruding mouthpart called a proboscis to drink nectar, most insects use their mandibles or appendages near their mouth to bite, manipulate and ingest food rather than a specialized tongue.
Similarly, spiders use their pedipalps and chelicerae to externally digest and suck liquids from prey caught in their webs or to chew food rather than having tongues in their mouths.
Conclusion
In summary, while the tongue is a multifunctional organ present in many animals, not every animal species has one. Mammals, birds, reptiles, amphibians, and most fish possess tongues. However, some invertebrates like sea stars lack tongues entirely.
There are also tongueless vertebrates like crocodilians, flamingos, some fish, and certain insects. So the answer is no, not all animals have tongues. But the amazing diversity of tongues across the animal kingdom allows species to taste, manipulate food, groom, swallow, and communicate in their own unique ways.
