Since jellyfish are not actually fish, some people consider the term jellyfish a misnomer, and American public aquariums have popularized use of the terms jellies or sea jellies instead.
Jellies first appeared about 650 million years ago and are found in every ocean, from the surface to the deep sea. Some are also found in fresh water.
A group of jellies is called a bloom or swarm.
Jellies do not have a brain or central nervous system, but rather have a loose network of nerves, located in the epidermis, which is called a “nerve net.”
Jellies are composed of more than 90% water. Most of their umbrella mass is a gelatinous material (the jelly), which is surrounded by two layers of cells which forms the umbrella (top surface). The subumbrella (bottom surface) of the body is known as the bell.
Jellies do not have a respiratory system since their skin is thin enough that the body is oxygenated by diffusion.
Jellies are dioecious; that is, 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.
Box jellies venom is the most deadly in the animal kingdon and 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.
The lion’s mane jelly is the largest known species of jelly. The Arctic Lion’s mane jelly is one of the longest known animals and the largest recorded specimen had a bell with a diameter of 7 feet 6 inches and the tentacles reached 120 feet. It was found washed up on the shore of Massachusetts Bay in 1870
Medusa (plural medusae) is another word for sea jellies. Medusa is also the word for sea jellies in: Greek, Finnish, Portuguese, Romanian, Hebrew, Serbian, Croatian, Spanish, French, Italian, Hungarian, Polish, Czech, Slovak, Russian and Bulgarian.
~ A sign seen on a restroom dryer:
Do not activate with wet hands.
~ In a grocery store:
Snickers, 5 for $1 (Limit 4)
~ At a motorway garage:
Please do not smoke near our petrol pumps. Your life may not be worth much, but our petrol is.
~ At an optometrist's office:
If you can't see, what you are looking for, you have come to the right place.