Jellyfish are fascinating creatures that have been around for more than 650 million years. They come in various shapes and sizes, with approximately 250 species worldwide. These ancient invertebrates have a long and mystical history and were once believed to possess magical powers.

Today, jellyfish continue to intrigue us with their unique biological characteristics, interesting behaviors, and variety of lifestyles.

The primary component of a jellyfish's body is water, making up over 95% of its body content. It is composed of two germ layers, with a mesocosmic layer in between. This layer is transparent and has a floating effect, allowing the jellyfish to move through the water in a fascinating way.

When in motion, jellyfish use the reflection of water spraying inside their bodies to propel themselves forward, resembling a round umbrella floating rapidly in the water.

Jellyfish have a special gland inside their umbrella that can produce carbon monoxide, allowing them to expand and contract their umbrella-like shape. This is useful when they encounter enemies or experience harsh weather conditions.

They can automatically release the gas and sink to the bottom, and when the sea is calm again, they can produce gas to make themselves expand and float.

Interestingly, jellyfish have a small ball with a hearing stone located in the middle of their tentacles, which serves as their "ear." Jellyfish reproduce by splitting, with one jellyfish splitting into several smaller jellyfish, which can then split again. They have an endless ability to reproduce, which makes them challenging to control in certain environments.

Jellyfish are passive feeders, mainly consuming tiny organisms in seawater, such as plankton and bacteria. They use their multiple tentacles to catch these tiny organisms, which they bring towards their mouth, located in the center of their umbrella.

Jellyfish are gregarious creatures and are often found in the tidal zone of the seafloor or in the deep sea. They can float or swim, and their tentacles can be used to feed and protect themselves. Their ability to continuously grow and divide makes them unique and challenging to study.

When jellyfish appear in groups at sea, they live closely together, resembling a deep floating on the surface of the sea. This is an awe-inspiring sight, with the azure surface dotted with many graceful umbrella-shaped bodies that shimmer in a faint light green or blue-violet hue.

Their slender tentacles stretch out in all directions, drifting along with them in beautiful colors and swimming postures.

Jellyfish play a significant role in the marine ecosystem as they serve as food for many marine animals, including sea turtles and certain fish species. However, some jellyfish populations have increased in recent years due to factors such as climate change and overfishing, leading to potential negative impacts on the ecosystem.

Some jellyfish species are also known to cause harm to humans through their stinging tentacles. It is important to understand the biology and behavior of jellyfish to better manage their populations and minimize their negative impacts on both the ecosystem and human activities such as fishing and tourism.

Jellyfish are ancient and captivating creature that continues to amaze us with their unique biology, behaviors, and lifestyles. As we learn more about them, we can better appreciate their role in the ecosystem and the importance of protecting them.