World Jellyfish Day is celebrated on November 3. Such an unusual holiday was initiated by a group of marine biologists who studied these creatures.

Jellyfish are invertebrate creatures that appeared on Earth more than 540 million years ago – much earlier than the first humans appeared. It is from this time that the oldest finds of fossilized remains of jellyfish date.

These unique creatures are 98% water. They have no bones, no brain, and no organs of vision, but they have 2 imperfect nervous systems. It is generally accepted that jellyfish have a transparent body, but among them there are bright representatives, and some glow in red or blue.

The sizes of these creatures vary from a centimeter to two meters. The Nomura jellyfish is considered the largest, weighing more than 200 kg.

Despite the fact that there are many jellyfish in the world, scientists are concerned that the deterioration of the ecological state of the ocean may lead to a sharp decrease in their number. Therefore, the purpose of the holiday is not only to attract attention to these interesting creatures, but also to preserve the environment as a whole.