Examples of animals that eat rocks include fish, chickens, crocodiles, crows, and ducks.
Eating rocks might seem strange to us, but it’s actually a pretty common behavior in the animal kingdom. You might be surprised to learn that there are creatures out there that use rocks to help them grind up their food, or even to digest their prey. Here are just a few examples of animals that include rocks in their diet.
Why Do Animals Eat Rocks?
A gastrolith is a term used to describe a piece of rock that has been consumed by an animal.
In animals without fully developed teeth that can chew food thoroughly enough for digestion, gastroliths are used as substitutes for molars, particularly in those with no complete set of teeth to do the job. The rocks tumbled around in the digestive tract as they eat, separating and crushing the flesh of birds, plants, or tiny fish caught by the animals.
Over time, the animals’ digestive juices softened the rocks and worn them down into pebbles. These pebbles are then excreted along with the other waste products. The whole process helped these animals to digest their food better and extract more nutrients from it.
Examples of Animals that Eat Rocks
1. Amphibians
| Scientific Name | Amphibia |
| Type of Animal | Reptile |
| Range | Worldwide |
Some amphibians, such as the green tree frog, eat small rocks to help them digest their food. The rocks grind up the insects that the frogs eat, making it easier for the amphibians to absorb the nutrients from their prey.
Interestingly, some frogs vomit up their stomach contents in order to escape predators. This ” projectile vomiting” is often effective because the frog can aim its stream of vomit at the predator, making it difficult for the animal to catch the amphibian.
2. Chickens
| Scientific Name | Gallus gallus domesticus |
| Type of Animal | Bird |
| Range | Worldwide |
Chickens are a common example of an animal that eats rocks. They use them to help grind up their food, and also as a source of essential minerals like calcium and phosphorous.
Related Article: Are Chickens Prey?
3. Crocodiles
| Scientific Name | Crocodylidae |
| Type of Animal | Reptile |
| Range | tropical regions of Africa, Asia, Australia, and the Americas |
Crocodiles are one of the best-known animals that eat rocks. They use gastroliths to help them grind up their prey, which includes small mammals, fish, and birds.
Crocodiles have been known to eat rocks for centuries. The ancient Egyptians even carved pictures of crocodiles eating rocks into their tombs. It wasn’t until recently, however, that scientists realized just how important rocks are to crocodiles’ diet.
4. Crows
| Scientific Name | Corvus |
| Type of Animal | Bird |
| Range | Worldwide |
You might not think of crows as rock-eaters, but it’s actually not uncommon for them to eat small stones. In fact, scientists believe that crows may do this to help them digest their food more thoroughly. The stones act like little grinding wheels in the bird’s digestive system, breaking down food particles so they can be easily absorbed.
Read Also: Are Crows Most Curious Animal in the World?
5. Ducks
| Scientific Name | Anatidae |
| Type of Animal | Bird |
| Range | Worldwide |
You might not think of ducks as rock-eaters, but some species of ducks actually consume small stones to help them grind up their food. These stones are called “grit,” and they reside in the gizzard—a muscular sac in the duck’s stomach that helps to break down food.
As the duck eats, the grit falls to the bottom of the gizzard where it is combined with food and other digestive juices. The gizzard then contracts and rubs the grit against the food, effectively grinding it up into smaller pieces. This makes it easier for the duck to digest its food and extract nutrients from it.
Related Article: How Much Does a Duck Cost?
6. Earthworms
| Scientific Name | Lumbricina |
| Type of Animal | Insect |
| Range | Worldwide |
Earthworms are a good example of an animal that eats rocks to help with digestion. They grind up the stones with their powerful muscles and teeth-like structures called grinders. The stones help to break down the tough plant fibers in the worms’ diet, making it easier for them to extract nutrients from their food.
7. Emus
| Scientific Name | Dromaius novaehollandiae |
| Type of Animal | Bird |
| Range | Australia |
Emus are large, flightless birds that live in Australia and New Guinea. These birds eat a variety of things, including insects, fruits, and seeds. But they also eat rocks! Emus swallow small pebbles and stones, which help to grind up their food in their gizzards.
8. Fish
| Scientific Name | Fish |
| Type of Animal | Fish |
| Range | Worldwide |
Some fish, such as the pufferfish and the loach, eat rocks to help grind up their food. The pufferfish is known for its odd diet of mainly hard objects, including gravel, coral, and seashells. It stores the rough objects in its stomach to help grind up the prey it eats.
9. Ostriches
| Scientific Name | Struthio |
| Type of Animal | Bird |
| Range | Africa |
These large African birds have a diet that is made up of mostly plant material, but they also eat small stones to help them digest their food. The stones help to grind up the food in their gizzard, which is an organ that helps to digest food.The bird’s gizzard is so strong that it can actually crack open the shells of nuts and seeds.
Related Article: Are Ostriches World’s Dumbest Animals?
10. Parrots
| Scientific Name | Psittaciformes |
| Type of Animal | Bird |
| Range | warm climates all over most of the world |
There are around 350 different species of parrot in the world, and they can be found in a variety of habitats, from rainforests to deserts. These birds are well known for their intelligence and their ability to mimic human speech. Parrots also have a unique digestive system that allows them to eat things that other animals can’t, like seeds, nuts, and fruits.
One of the things that helps parrots digest these hard foods is their diet of pebbles. Parrots will often eat small rocks to help grind up their food in their gizzard. The rocks help to wear down the seeds and nuts, making them easier to digest.
Related Article: Do Parrots Eat Flowers?
11. Penguins
| Scientific Name | Spheniscidae |
| Type of Animal | Bird |
| Range | below the equator |
You might not think of penguins as rock-eaters, but they actually consume quite a bit of stone each day. Penguins need lots of calcium to keep their bones strong, and they get this nutrient by eating small rocks. The stones also help penguins to grind up their food before swallowing it.
Related Article: 15 Birds that Look Like Penguins
12. Sea Lions
| Scientific Name | Otariinae |
| Type of Animal | Mammal |
| Range | on the coasts of Japan and Korea, western North America from southern Canada to mid-Mexico, and the Galápagos Islands |
Sea lions are another type of marine mammal that ingests rocks. Unlike walruses, however, sea lions don’t use them for grinding up food. Instead, they appear to eat small rocks and pebbles to help with their digestion.
13. Seals
| Scientific Name | Pinnipedia |
| Type of Animal | Mammal |
| Range | along most coasts and cold waters, but a majority of them live in the Arctic and Antarctic waters |
These marine mammals are known to eat rocks, which help them to grind up the hard shells of crabs and other prey.
14. Ship Worms
| Scientific Name | Teredinidae |
| Type of Animal | Insect |
| Range | Worldwide |
These strange creatures look more like plants than animals, but they actually have a soft, segmented body inside their hard shell. Shipworms bore into wood, using their powerful teeth to grind it up and extract the nutrients they need. They also consume the shells of mollusks, and some species of shipworm will even eat rocks.
15. Toothed Whales
| Scientific Name | Odontoceti |
| Type of Animal | Mammal |
| Range | South Atlantic, Indian, and South Pacific Ocean |
These marine mammals use stones to break down the tough material in their prey. The stones are stored in the animal’s cheek pouches and brought up to the mouth when it’s time to eat.
16. Turkeys
| Scientific Name | Meleagris |
| Type of Animal | Bird |
| Range | much of the eastern U.S., spanning from the Canadian border to northern Florida and westward to the Mississippi River |
One of the most common animals that eat rocks are turkeys. They use stones to help them grind up their food, and they often swallow them whole.
Related Article: Do Turkeys Imprints?
Conclusion
Though it’s not common, a variety of animals consume rocks to help them digest their food. The stones act as grinding wheels in the digestive system, breaking down food particles so they can be easily absorbed. This process helps the animals extract more nutrients from their prey, making them better able to survive.
Hi, I’m Garreth. Living in South Africa I’ve had the pleasure of seeing most of these animals up close and personal. When I was younger I always wanted to be a game ranger but unfortunately, life happens and now at least I get to write about them and tell you my experiences.