What are jellyfish?

It was another great weekend on the beach for my family and everyone had new and exciting Beach Chair Scientist questions. The best part about being a Beach Chair Scientist is clarifying misconceptions, so I am going to start with the question that seemed to garner the most discussion this weekend “What are jellyfish?”.

Jellyfish, contrary to their popular common name, are not fish at all! As a matter of fact, neither are starfish. Popular nicknames to avoid this misconception can be to call them jellies or seastars.

Jellies are basically giant plankton. Plankton is anything (living) that is free-floating. It can be a plant (known as phytoplankton) or an animal (known as zooplankton). Jellies are zooplankton. Floating is easy for them. They are over 90% percent water. People are approximately 70% water.  Jellies are in the family Cnidaria (the c is silent). Also in this group are sea anemones and coral.

What do jellies, sea anemones, and coral all have in common?

1. One giant cavity for all digestion
2. Stinging cells (known as nemotacysts)
3. Tentacles
4. Radial symmetry (no matter how you slice it, you will have 2 halves)

Jellies are essentially a giant mouth with intestines surrounded by a skeleton. They have a nerve-net surrounding their transparent skeleton. The nerve-net in some species extends towards the tentacles. Not all jellies have painful toxins in their tentacles.

What do you do if you are infected with a toxin tentacle?

1. Wash with soap and water
2. Apply alcohol, or meat tenderizer and Vaseline
3. Apply ice and contact a doctor

Image (c) pdphoto.org

Do you have another great question? Email info@beachchairscientist.com and just let me know.