Yes, as unusual as they look. Jellyfish are indeed very unique organisms – No Heart, No Brain, No Blood, No Problem. But don’t be fooled, some species of Jellyfish are one of the most deadly in the animal kingdom.
Jellyfish have No brain or central nervous system, but rather have a loose network of nerves, located in the epidermis, which is called a “nerve net”
The Box jellyfish venom is the most deadly in the animal kingdom. It has caused at least 5,568 recorded deaths since 1954. Each tentacle has about 500,000 sindasites which are harpoon shaped needles that inject venom into the victim
Jellyfish are composed of more than 90% water. Most of their umbrella mass is a gelatinous material (the jelly) called mesoglea, which is surrounded by two layers of cells forming the umbrella (top surface). The subumbrella (bottom surface) of the body is known as the bell
Jellyfish are not actually Fish (so what’s with the name???). Some people consider it non-appropriate. In fact, American public aquariums have popularized the use of the terms “Jellies” or “Sea Jellies” instead.
Jellyfish are “dioecious” – they are either male or female. In most cases, to reproduce, both males and females release sperm and eggs into the surrounding water, where the (unprotected) eggs are fertilized and mature into new organisms
Medusa (plural medusae) is another word for Jellyfish. Amazingly- Medusa is also the word for jellyfish in Greek, Finnish, Portuguese, Romanian, Hebrew, Serbian, Croatian, Spanish, French, Italian, Hungarian, Polish, Czech, Slovak, Russian and Bulgarian