Jellyfish are 95% water.

Jellyfish are 95% water.

Fascinating, elegant, and mysterious to watch in the water, take a jellyfish out of the water, and it becomes a much less fascinating blob. This is because jellyfish are about 95 percent water. Lacking brains, blood, or even hearts, jellyfish are pretty simple critters.

Jellyfish are found all over the world, from surface waters to the deep sea. Scyphozoans (the "true jellyfish") are exclusively marine, but some hydrozoans with a similar appearance live in freshwater. Large, often colorful, jellyfish are common in coastal zones worldwide.

While most jellyfish live only about three to six months, some live longer and can survive for two to three years. After all, the immortal jellyfish never technically dies. Instead, it eventually settles on the seafloor and contributes to the birth of a younger jellyfish from its own DNA.