5 Interesting Facts About Jellyfish That Everyone Should Know

1. Jellyfish Are Older Than Dinosaurs

Jellyfish have been drifting through the oceans for over 500 million years, making them one of the oldest living creatures on Earth. They existed long before dinosaurs roamed the planet and have survived through multiple mass extinctions.

2. They Have No Brain, Heart, or Bones

Jellyfish are simple creatures with no brain, heart, or bones. Their bodies are made up of about 95% water, and they rely on a basic nerve net to sense changes in their environment and respond accordingly.

3. Some Jellyfish Are Immortal

The species *Turritopsis dohrnii*, also known as the “immortal jellyfish,” has the unique ability to revert its cells back to their earliest form after reaching maturity. This process can theoretically allow it to bypass death and start its life cycle anew, making it biologically immortal.

4. They Can Be Deadly

While many jellyfish stings are harmless, some species, like the box jellyfish, are among the most venomous creatures in the world. Their sting can cause severe pain, and in some cases, it can be fatal if not treated immediately.

5. Jellyfish Blooms Can Disrupt Ecosystems

Jellyfish can reproduce rapidly, leading to massive blooms that can disrupt local ecosystems. These blooms can clog fishing nets, damage marine life, and even cause problems for power plants by blocking water intake pipes.

FAQs About Jellyfish

What do jellyfish eat?  

Jellyfish primarily feed on small fish, plankton, and other tiny sea creatures. They use their tentacles to capture and paralyze their prey before bringing it to their mouth.

Are jellyfish dangerous to humans?  

Some jellyfish species can be dangerous to humans due to their venomous stings. While most stings cause only mild irritation, others can be life-threatening, especially those from species like the box jellyfish.

How do jellyfish move?

Jellyfish move by contracting and relaxing their bell-shaped body, propelling themselves through the water in a pulsating motion. They also rely on ocean currents to carry them over long distances.

Can jellyfish live in freshwater? 

Most jellyfish are marine animals, but some species can live in freshwater. For example, the freshwater jellyfish *Craspedacusta sowerbii* is found in lakes and rivers around the world.

How long do jellyfish live? 

The lifespan of a jellyfish varies by species. Some live for only a few hours, while others can survive for several years. The “immortal jellyfish” can theoretically live indefinitely under the right conditions.

Conclusion

Jellyfish are remarkable creatures that have thrived in the oceans for millions of years. Their simple yet effective biology, ability to disrupt ecosystems, and, in some cases, their potentially deadly sting make them both fascinating and important to understand. Whether you’re intrigued by their ancient lineage or their unique adaptations, jellyfish are certainly among the most interesting animals in the sea.