How Do Cactus Protect Themselves?

The mighty old cactus is the King of deserts.

Pachycereus pringlei, known as the Mexican Giant Cardon, is the tallest cactus in the world, with a height of 63 ft. and 3 ft. 3 inches in diameter.

It is more than 300 years old and is still standing tall. A cactus has the potential to grow even taller in a span of 200 years, depending on how it adapts to the environment.

This begs the question ― How does a cactus survive that long?

From humans to animals and bacteria, a cactus has many enemies.

While human beings don’t set out to kill a cactus, their neglect does the job.

Despite all the threats, this succulent can survive in intense heat and without water.

How? Let’s talk about it:

Understanding a Cactus

What’s the first thought that comes to your mind when you see a cactus?

Do you experience wariness at the sight of the spines? Though cactuses are beautiful, especially when their flowers are blooming, most people still view them from a distance.

Ask a horticulturalist, and they will tell you how difficult it can be to conduct experiments when a cactus is involved.

So, what do you think those spines on a cactus do?

The Relation Between Cactus and Spines

You would be surprised how a cactus’s defense mechanism works. Its botanical barbarity, we tell you!

The answer is pretty simple, which you probably know. The spines help keep any living being away from harming the cactus.

Think of them as modified leaves, which make a cactus just a large stem with spines.

The sharp spines turn away most of the animals. However, a few are ready to get pricked to have their meal.

These animals include desert tortoises, bighorn sheep, pack rats, and wild pigs. In fact, the spines are a part of their diet.

Another surprising function of these spines is that they provide shade. It might sound a bit skeptical about how the tiny spines could offer the cactus any real protection but consider this:

A single spine offers a thin line shade. Combine more than 1,000 spines, and the cactus has got an umbrella.

The spines go one step further and also prevent water evaporation.

The Cholla cactus’s spines serve one more purpose ― they aid in propagation. The spines have an extension, which are tiny barbs on the tips. This makes the cactus very sensitive to any movement nearby.

As a result, if someone walks by, whether it’s a human or an animal, the segments jump out, attaching themselves to the skin.

Though they don’t actually “jump,” they do stick to the host. When the segment detaches and falls to the ground, it plants itself in the soil, growing a new Cholla cactus.

The Roles of Spines in the Survival of a Cactus

A cactus’s spines go beyond that, pricking animals and humans. They offer cactus protection in many forms.

Reduce Moisture Loss by Trapping Air

The spines help create a buffer, which traps air. This is necessary for controlling airflow, or else water will escape from the plant.

As a result, the cactus dries up fast, leading to a curved stem and spots that indicate the presence of bacteria. This also attracts rodents.

In the desert, the buffer is what helps a cactus survive. You don’t have to worry about this when you have a cactus planted in your backyard.

You simply need to make sure that it is not overwatered, or the plant will turn squishy.

Collect Water for Survival

The Atacama Desert, located in Arica, Chile, is the driest desert in the world.

The landscape is arid beyond imagination that NASA astrobiologists make the long journey to find out if the desert might reveal any clues about signs of survival on other planets.

The desert experiences frequent heavy fogs in the morning hours, which the locals call camanchaca. The heavy dew increases the survival rate of cactuses.

Once the fog settles, dew can be seen on the cactus spines. This dew liquefies into the water, which then flows on the ground.

The roots of a cactus absorb this water, which helps nourish it. As a result, the cactus is able to survive the harsh heat of the desert.

According to a study, cactuses have a hierarchical groove structure, which is unique in shape and helps the succulent collect water.

Offer Shade That Prevents Loss of Moisture

As said earlier, you might assume that the spines on a cactus don’t do much, but they are solely responsible for this plant’s survival.

In fact, when a cactus sprouts, the spines appear first before the stem. The thin radius of the spines plays a huge role in keeping a cactus healthy

The dense population of the spines covers a huge surface area. Therefore, the shade adds up and prevents the cactus from losing water. This plant might be a prick, but it has good intentions.

Protects from Predators

A desert is crawling with all types of insects and rodents who love munching on anything green. They are not picky because of the area they are in, which makes cactuses fair game.

This is where the spines come in. They prevent herbivores from getting too close, and those who dare try to munch on the plant get pricked.


A cactus has wide and shallow fibrous roots that are near the surface and help absorb rainwater quickly.

Though the desert is usually dry, it does experience a few rain spells. Some cactus roots grow up fast during this weather, at a speed of about 2 hours.

However, once the rainy season passes, the roots wither away.

Since there’s no more water to be absorbed, the roots die a slow death. So, you can say that the more frequent the rain, the faster a cactus will grow.

This is why cactuses only grow a couple of inches in 10 years.

Some cactuses have taproots along with fibrous roots. These roots grow underground, reaching deep, and get access to large concentrations of minerals that are tolerated quite well by animals, plants, and humans.

The taproots are also 3 to 4 times longer than the height of the cactus above ground. Since taproots absorb water that is present underground, cactuses having this plant phytotomy are stronger.

Deep-Layer Stomata

The stomata of cactuses are located deep inside the tissue rather than on the surface. The stomata wake up at night for photosynthetic adaptation.

This process is known as Crassulacean acid metabolism (CAM); when combined with the stomata, it reduces water loss significantly.

This is extremely important for a desert environment and ensures the plant doesn’t dry up and wither away.

Expandable and Thick Stem

The stem of a cactus is similar to that of a basic succulent.

However, the former’s is thicker, and that’s how it absorbs every drop of water and stores it in water-storage cells.

One of the unique features of a cactus’s stem is that it also expands so that more water can be stored.

Waxy Skin

The surface of a cactus, except for the stomata, is covered with a waxy layer. This layer helps prevent excess evaporation and retains moisture well.

Does a cactus have predators?

Though a cactus has prickly armor, it’s not immune to rodents and animals.

The former species gnaw on the cactus pad, and mammals such as humans and bears enjoy the plant’s fruits.

In some cases, the plant itself is also edible. It just needs to be unspiked.

How does a cactus defend itself against herbivores?

A cactus’s first line of defense is its impenetrable barrier, which is composed of a waxy cuticle and bark.

Both protect succulents from herbivores. There are a few other plants that protect themselves with the help of spines (modified leaves), thorns (modified branches), and hard shells that the

Do animals enjoy eating a cactus?

When it stops raining and the weather is extremely dry, animals have no choice but to eat cactus. The most common type they prefer is the prickly pear cactus.

Animals such as beetles, birds, squirrels, deers, pack rats, jackrabbits, antelopes, and javelinas will eat the cactus fruit.

The rodents distribute the seeds through feces, which is how a vast surface is covered so quickly with varying heights of cactuses.

Final Thoughts

Botanical barbarity is real. It’s not just a term coined to explain plants can be vicious too.

Like every other plant, a cactus also takes some extreme measures to protect itself.

Apart from the obvious spines, which make humans and even animals wary, the phytotomy of a plant also plays a vital role in survival.

From preserving water to the waxy layer that prevents loss of nutrients and maintaining a certain shape to avoid sunburn, the cactus goes the extra mile to stay standing and strong.

If you are planning to plant a cactus in your backyard, there are a few basic things you need to know about its maintenance.

In the desert, the succulent’s survival is based on rain.

At home, you need to create a watering schedule, surround the cactus with other plants so that pests leave it alone, and change the soil if the cactus is not growing.

As for how much and how often you need to water your cactus, the answer is two cups and once a week.