In science, a tail has a loose definition but overall, it means any part of an animal’s body that protrudes from the hind legs or the rearmost legs. In general, a tail serves a purpose. In this article, I will cover 10 animals that don’t have a tail, and why it is that they don’t need one.
Some animals that don’t have tails are:
- guinea pigs
Typically, a tail wasn’t required to give these animals a competitive edge, or other adaptations were made that no longer required a tail.
Each of these animals does not have a tail for specific reasons. Below, I will explain in detail the reasons why each of these animals doesn’t have a tail, and the main reasons why some animals have tails, and other animals don’t.
Starfish have a small body in the center of 5 legs. Starfish are predator animals that eat shellfish by prying them open with their suction cap feet. However, they are also a favorite snack of many other animals.
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A key feature of animals with a tail is some of them can drop their tail as a distraction, and the predator that is trying to eat it will instead eat the tail because it’s an easier snack and provides an instant reward.
Starfish move incredibly slowly, and if they dropped a tail they would still get eaten. Starfish rely on hiding and camouflage as a defense mechanism to avoid getting eaten. If a starfish is unlucky it will get found and eaten by:
- certain types of fish
- other starfish
Starfish are near the bottom of the food chain, much like plants that also can’t get away easily. So, if found by something that wants to eat them, they will most certainly get eaten.
Other than not needing a tail as a defense mechanism the other reason starfish don’t need a tail is due to the way that they move. A tail on a starfish would create drag and slow them down, without any additional benefits.
Apes are a type of monkey that doesn’t have a tail. Monkeys are a scientific term for the animals you’ll be familiar with such as lemurs and spider monkeys. Monkeys are overall smaller than apes, and live a large part of their life in trees.
Apes by contrast are larger and spend a lot of time in grasslands and on the forest floor.
Monkeys primarily use their tail for balance, and to cling to tree branches. Many monkeys can also hang from a tree by their tail. But, since apes spend most of their time on the ground they don’t need the advantage a tail could provide.
The tail of a monkey is not used as a defense mechanism. Their main form of defense is their agility.
They can typically outpace a predator in the trees such as a jaguar, or a snake. But, they also are herd animals and will look out for each other to avoid snakes like boa constrictors that can sneak up on them
There are very few proposed theories as to why apes don’t have tails. One of the advantages of a tail is it provides a lid over the anus to protect it from parasites.
However, many apes have large buttocks which stick out and provide cover for their anus. Therefore, unlike monkeys, apes don’t really have much need for a tail.
Octopuses are fascinating animals that swim but can also walk on the ocean floor. They have a beak-like mouth in the center of their 8 legs. The main predators of octopuses are:
- large fish
Octopuses don’t have a tail because it wouldn’t help them to catch prey. A regenerative tail like that of a gecko could be advantageous to an octopus to escape from predators. But, it appears octopuses rely on other defense mechanisms to avoid predators.
One main defense mechanism of an octopus is to squirt ink which clouds the water. This distracts and disorients a potential predator, so the octopus can swim away very fast to safety.
The other is that many species are also able to change color to match their surroundings, they have very flexible bodies which they can shape to look like rocks and perfectly blend into their surroundings when they spot a predator hanging about.
Some species such as the mimic octopus will also change their shape to look like other animals. The animals they mimic are those that their predators don’t want to eat or attack such as lionfish, or sea snakes.
Here’s a cool video of a mimic octopus changing its shape and color:
Octopus feed on sea shells and crabs. They can pry open sea shells with the suction cups on their arms. Interestingly, octopuses poop from a large hole at the top of their tentacles at the bottom of their head/bodies.
A tail would not do much to protect the anus because of the motion of water currents. There is also very little gravity underwater, so a tail would move and blow around and expose its anus if it did in fact have one. So, a tail to protect the anus would not be very effective.
The main reason an octopus doesn’t have a tail is they have other defense mechanisms, and it would ineffective to protect its anus.
The shape of their body allows them to swim and change direction with ease, so they don’t need a tail for extra balance. Their suction cup tentacles are also more than enough to cling to rocks and plants to keep their balance in strong currents.
As you may know, spiders are insects but are classified differently because they have 8 legs, instead of 6. All spiders lack a tail. Some spiders will go and hunt other insects without using a web. Whereas, others will build a web to catch insects that happen to wander or fly into it.
The main predators of spiders are:
- other spiders
If a spider is spotted by one of these predators it will quickly kill it by:
- breaking its body into pieces
- swallowing it whole
- paralyzing it with venom
A spider has no real need for a tail, and it would not provide any protection from predators, or help them to move around. Spiders are also small enough that most parasites are far too big to try to enter their anus.
Spiders for the most part are perfectly balanced on all 8 legs, and a tail wouldn’t provide any additional balance while walking and climbing. If a spider falls from a tree it will typically survive, because they tuck up into a ball and roll.
FUN FACT: Spiders use silk to keep them attached to things during high winds or take cover to avoid very windy conditions.
Some spiders have tail-like appendages on their thorax. Similar to extra small legs, which they use to produce and shape silk. These look somewhat like a tail but are not true tails.
Capybaras are native to South America. They are the world’s largest rodents and primarily live in:
- dry land
Unlike their close relatives the rat, they have no tail at all. This is because, unlike rats, capybaras don’t climb in trees. Rats will typically use their long tail to wrap around tree branches for stability.
A capybara primarily walks around on the ground or swims in bodies of water. They also have partially webbed feet which allow them to swim very well.
Male capybaras have an unusual penis that is located very close to their anus. It is retracted in the body and not visible. But, when they mark their territory or reproduce it extends outwards. If they did have a tail the direction that it extends would be in the way and make it more difficult for their penis to exit their body.
Capybaras are herd animals. A few of the herd are always on the lookout for predators while the others relax and feed. They have many natural predators such as jaguars and crocodiles.
When a predator is near a capybara’s primary defense is to run to the water, where it can hold its breath for around 5 minutes. They can also run very fast and are incredibly agile.
They can typically outmaneuver a predator. In the water, they rely on their senses to avoid crocodiles, and if they are lucky to sense one approaching they will make their way out of the water onto land where crocodiles are very slow.
FACT: Since capybaras are easily outmatched in a fight with their predators, a tail wouldn’t help them to defend themselves.
Koalas are a very slow-moving animal native to Australia. They live most of their life in trees, and interestingly, spend 90% of their life sleeping and the other 10% eating.
They are a marsupial, in the same family as kangaroos, and are distinct from other families of animals because their young spend the early part of their lives in their mother’s pouch.
Although koalas live in trees, they have no tails because they have very well-adapted hands. They have long curved claws that are perfectly suited to holding on to tree branches. Koalas, unlike some other tree dwellers, don’t move fast and primarily use their hands to hold on and not fall.
They can survive and thrive without needing to move fast and don’t have a tail because they have very few natural predators. A koala’s main risk is its young getting swooped up by a bird of prey, or a dingo catching them in the limited amount of time they spend on the ground. A tail would not help them when this happens.
#7: All Insects
All insects don’t have a tail. Insects are unique because their body is typically divided into three parts. A head, abdomen, and thorax. Some insects have what looks like a tail.
For example, stick insects have long thin bodies that extend beyond their rear legs. These can technically be called a tail. But, they aren’t a tail in the traditional sense, like those found on mammals such as horses, or monkeys.
However, although in appearance they can look like a tail, they are not a tail in the traditional sense. All insects have different defense mechanisms, and it would be too much to explain them individually.
Worms come in a range of different colors, sizes, and shapes. Although they can look reasonably different their body is always the same: one continuous noodle-like structure.
Worms, as you may know, spend the vast majority of their life on the ground. Here they can largely avoid predators. Worms move very slowly they could never escape if they are caught by animals like:
If worms had a droppable tail, it wouldn’t work well as a distraction because by the time a predator ate the tail, the worm would still be in the same area.
Therefore, they don’t need a tail as a distraction. Worms feed on soil and organic matter in the ground. As they feed, they poop what looks like fresh soil.
A tail would not serve much of a purpose to protect the anus because the whole worm is permanently covered in soil. Also, much like spiders, their body is far too small for parasites to enter through the anus.
It could serve the purpose of helping them probe into the soil, and make it easier to burrow if they were to travel backward. But, worms move in the direction of their head, where they consume organic matter and soil as they go. Therefore, a tail wouldn’t provide worms with any additional benefits.
#9: Fruit Bats
A fruit bat is a very large bat, that is also called a flying fox. That’s because it has an orange patch of fur around its neck and all along its body similar to a fox. Flying foxes look beautiful when they fly and grow very large about the size of a small household cat, but with very large black wings.
They are found throughout Australasia, Oceania, and South East Asia. As the name of this bat suggests it eats fruit. It also loves to hang upside down from branches from its feet where it can easily let go and fly to its next destination.
The natural predators of fruit bats are:
- large owls
If any of these predators were to attempt to catch a fruit bat a tail would not help it survive.
They are very adept flyers and although a tail could help them change direction, fruit bats have developed a lot of skills in flying without one. They are also completely featherless, so couldn’t have feathered tails. A tail on a fruit bat would serve no real purpose, or help them to feed or survive.
#10: Guinea Pigs
Guinea pigs are native to South America. They are tiny rat-sized animals, that are incredibly cute and are common pets the world over. The main predators of guinea pigs are birds of prey and weasels.
A guinea pig’s main form of defense is to run for cover and evade predators. They also are herd animals, and keep safe by alerting each other about a bird of prey overhead, or if they hear or see a weasel approaching. Mammals don’t have tails that can drop off and regrow, so guinea pigs couldn’t have a tail of this type.
Guinea pigs have very short legs, and their butt is very close to the ground. The shape of their body would make a tail impractical because it would bump and potentially drag along the ground.
If they had a long and thick tail it could help them with balance as they walk. However, because guinea pigs are agile and can run very fast, a tail would slow them down and make their main defense mechanism not as good.
Hyrax are unusual-looking small rodents and look like large rats. They are native to Africa. Their head is smaller in proportion to their body compared to a rat. Their natural predators are:
- birds of prey
- big cats (like leopards and jaguars)
Hyrax can also live in large herds of up to 80 individuals. This provides more pairs of eyes to spot an approaching predator, and ears to listen out for their approach.
Their main defense from predators is to run and hide in narrow cracks in rocks, or burrows that are too small for predators to get into.
They are very agile and fast and provided they notice their predators they can almost always get away. Like guinea pigs, they have very short legs, and their butt is very low to the ground.
Also, unlike rats, they don’t climb trees, so have no need for a tail to hold on to branches. A tail would also make it easier for predators to catch them before they can make it to the safety of a crack or burrow. A tail wouldn’t offer any real advantages to hyrax.
Does Every Mammal Have a Tail?
Mammals are a very large category of animals that are classified based on the distinct differences they have from:
But, here’s whether every mammal has a tail.
Not every mammal has a tail. Mammals without a tail don’t have one because it serves no use during their life cycle. Examples of mammals that don’t have a tail are:
- guinea pigs
- koala bears
Some mammals also have very small tails such as:
There is a range of reasons why this is, which varies from animal to animal. The current understanding is that evolution plays the biggest role in whether mammals have a tail, an animal only has a tail if it serves some purpose that helps it to survive or reproduce.
Why Do Some Animals Have a Tail But Others Don’t?
Not all animals have tails. For some animals, it’s obvious what they use their tail for. Whereas, for others and can seem a bit odd that they don’t have a tail. So, here are the reasons why some animals have a tail but others don’t.
In general, animals without a tail don’t have one because:
- Their body shape is too low to the ground and it would get in the way.
- They don’t need it to grab onto tree branches because they mostly live on the ground.
- Having a tail would make it easier for them to get caught by a predator.
The main functions of a tail in animals are:
- Keeping track of the herd
- swatting flies, bugs, and birds
- defense mechanism
- protect the anus from parasites
- a rudder for swimming
- to help them to swim
- to whip prey to immobilize them
If an animal doesn’t have a tail, it’s because its mode of life means they don’t need it for one of these purposes. Their body can also be a shape and size where they don’t require a tail for one of the above reasons.
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