Wednesday, October 26, 2011

What are jellyfish?

Jellyfish live very complicated lives and have a strange life cycle. I want to take the time to really explain what jellyfish are and how their life pans out. So I will start with the simplest stage of their life.

What is a jellyfish? 
Jellyfish are known as medusas. medusa refers specifically to the stage of a jellyfish's life that we all know and recognize; the jellyfish.

A jellyfish is a simple marine organism from the phylum Cnidaria. Cnidaria encompasses many corals, anemones, hydrozoans, cubozoans etc. True jellyfish are a class known as scyphozoans. Moon jellies, sea nettles, cannonball jellies (plus many many more) are scyphozoans.

There are other types of medusa, however scientifically, they aren't actual jellyfish. These medusa are all still cnidarians, they just aren't scyphozoans. I still generally refer to these medusa as jellyfish because they are very close and there is no use in getting caught in the little specialized names and classes. Examples of these include hydrozoans and cubozoans. Hydrozoans include jellies such as the crystal jellyfish or the cross jellyfish. cubozoans encompass jellyfish with four sides that form a cube shape as their bell. these are also known as box jellies. Some cubozoans are extremely toxic and others are not.

Jellyfish structure and makeup. 


There is an extreme diverse population of jellyfish in existence right now. Jellyfish within their class tend to be similar in body layout, however.

~Scyphozoans~

~Hydrozoans~


~Cubozoans~


So here are the three basic types of jellyfish. A lot of this information is not necessary to own a jellyfish. however I think it should shed some light on the first stage of the jellyfish. Part two will be on planula!

Credits to~

  • http://www.ucmp.berkeley.edu/cnidaria/images/CuboMorph1.jpg
  • http://www.esu.edu/~milewski/intro_biol_two/lab_9_porifera_cnidaria/images/hydrozoan_medusa_diagram.jpg
  • http://cronodon.com/files/Jellyfish_diagram_2.jpg

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