12 April, 2011

A-Z Blogging Challenge: J Stands For: Jellyfish

Jellyfish are members of the phylum Cnidaria (also known as Coelenterate), which is the same phylum as coral. They aren't actually fish--they are invertebrates. The term jellyfish can also refer to the phylum Ctenophora, of whose members are not closely related to Cnidaria but are also free-swimming planktonic carnivores.

Jellyfish do not have brains or eyes or bones, and nor do they have specialized digestive, respiratory, or circulatory systems like so many other animals.

Instead, they digest by absorbing nutrients in their gastrovascular cavity through the gastrodermal lining. They move by using their hydrostatic skeleton, in contractions and pulses. Jellyfish also have small sacs located at the rim of their bell-shape that sense in what direction the animal is traveling: they trigger nervous reactions when the jellyfish is heading too far in one direction. Humans have similar sacs in their ears.

They are more than 90% water. Most of their mass is the mesoglea, the jelly part, surrounded by two layers of epithelial cells. The epidermis is the external body surface, and the gastrodermis is the internal surface.

A jellyfish's "nerve net" is a network of nerves located in the epidermis. The nerve net is used to detect stimuli, such as the touch of another animal; impulses are sent through the nerve net, around a circular nerve ring, through the rhopalial lappet (rhopalium are "small sensory structures"), and then to other nerve cells throughout the body. Jellyfish also have ocelli, which are light-sensitive cells that can detect whether the animal  is swimming up or down.




Have you ever seen--or been stung by--a jellyfish?

Also, as some of you may have noticed, I changed the layout of my blog from a three-column to a two-column and adjusted some of the fonts/colors. What do you think?

-----The Golden Eagle
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Siv Maria said...

Interesting and beautiful but they do burn bad if encountered. Best thing to do is to pee or have someone pee on the burn. I know sounds weird but it does work...lol, I am living proof...æshhhhhhhh. Love your post, always do.

the writing pad said...

Your posts are always so interesting - thanks for this one on the humble Jelly Fish!
All best

Simon Kewin said...

Fascinating creatures - thanks!

Pk Hrezo said...

Wow, look at the size of that thing! Amazing! I think jellies are beautiful, but they do hurt. I've been stung by them many times. THankfully, it doesn't last long.

Happy J Day! :)

L.G.Smith said...

They're not fish at all. They're aliens. Gotta be. :)

Tiger85 said...

I have only seen them in a tank at a zoo and an aquarium. I did know someone that was in Florida and had a jellyfish swim up his shorts and sting him. I didn't know all this about jellyfish. Thanks for sharing. =)

Poetry, Quotes and Book Reviews.

Elena Solodow said...

One summer, the beach my family always goes to was flooded with jellyfish. The currents changed or something and they came inland. It was disgusting to swim in!

Anonymous said...

Jelly fish are so cool!:D

Old Kitty said...

I will never forget getting stung by stinging jelly fish when I was like 6 years old on my day out at the beach - boy that was painful!!

I think they're absolutely wonderful creatures though, so diverse and amazing!!!

ps. some of your pics didn't show up but that's ok cos I got to see most of them!! Yay! Take care

Michael Di Gesu said...

graceful and beautiful, but I stay clear of them....

JRandSue said...

Outstanding photography,beautiful Images.

Hilary Melton-Butcher said...

Hi .. we chose the same subject - I'm surprised at that .. but your post is more exotic and your pics are wonderful .. Siv wrote about peeing on any stings over on my blog too!

Great post .. different facts etc .. thank goodness! Cheers Hilary

Ann said...

I did not know that the sacs Jellyfish have in their belly are similar to the sacs in Human ears. I have learned something interesting today. Yay for A-Z!

The Writing Goddess said...

I picked Jellyfish, too - but as they relate to writing and music. Writing in Flow

Don't know if it's just me, but a couple of your pics aren't showing up. (sad face.) I'm happy to living somewhere I can go see them on a regular basis.

Michelle Merrill said...

I really love your thirst for knowledge! Thanks so much for sharing. The pictures are great. I haven't ever touched a jellyfish but I've seen them on the beach.

Sofia said...

That's awesome!

I personally like the three-column look better, it feels more clean and less crowded to me.


Josh Hoyt said...

Great pictures. I have a salt water tank and have loved the amazing animals that come from the sea. I think that jelly fish are amazing crustaceans.

Sofia said...

Oh! I realized I forgot to put this in my last comment-- when swimming in the mediteranian (sp?) a few years ago, my mom got stung by a jellyfish. That was in the Cinque Terre, on the coast of Italy. I've seen tons of jellyfish where I live, since I live on the coast. Sailing and going to the beach are where I've seen them, along with the aquarium. :D


Ricky said...

Excellent post. One of them appeared close to me in the sea a few years ago. I got out of there pretty quickly.

Jerri said...

Luckily never stung. They are beautiful.

klahanie said...

Fascinating and most interesting info on the Jellyfish. I thank you for sharing this along with the wonderful photos.
And thus the 'alphabet challenge' continues. Have fun and cause I already know the alphabet, I know that the next letter will be 'K'.
Oh, before I go, I thought in America, a Jellyfish would be called a 'Jellofish'. Sorry, that was lousy, but what the heck, you've received a comment from me, yes, shy and humble me :)
Take care and enjoy.

The Words Crafter said...

There are so many kinds of jellyfish! The kids in my class love looking at the picture I bring them.

I went swimming once in part of the Chesapeake Bay. The first time I ever saw any sort of jelly. Fortunately, I didn't get stung!

Alex J. Cavanaugh said...

They are an incredible creation of nature!

Alleged Author said...

The Moon Jellyfish have always been my favorite. At the aquarium in Chicago, they have a huge tank full of them. I often used to sit and watch them.

Jemi Fraser said...

Jellyfish are extraordinarily cool! Always look so ethereal & other worldly :)

kmckendry said...

These are beautiful pictures you found.

Trisha said...

Living in Australia, and in an area right between an ocean and a river, yes, I have seen plenty of jellyfish ;) Stepped on a few too, by accident!

Cindy said...

Jellyfish are neat :) I've only been stung once, and it was kind of wierd... there had been a storm and there were a bunch of long tentacles of jellyfish in the surf but we never saw and of the "body" of the jellyfish.

Anonymous said...

They are quite beautiful. Makes me think of the movie Finding Nemo. :)

Cally Jackson said...

Amazing images! I've been stung by a blue bottle when I was a child. I've also seen some very silly boys (in their 30's no less) whip each other with blue bottles, causing welts all over them. Silly, silly boys!

Edith F. said...

My family and I found a dead jellyfish while walking on a Pacific beach many years ago. It was like a blob of clear... well... jelly. I hadn't realized before how much of their form they get from the buoyancy of water.


Carol Riggs said...

Those are gorgeous photos! How weird--no brains, eyes, or bones! I think your blog looks great, nicely simplified. :)

The Golden Eagle said...

Siv: LOL. I'll have to keep that in mind--really. :P

I'm glad you enjoyed the post! :)

Karla: You're so welcome! Thanks.

Simon: They are!

You're welcome! :)

Pk: They're aptly called giant jellyfish; apparently it's a problem in Japan.

I've never been stung--and hopefully won't be!

Thanks! :D

L.G.: LOL. They do seem like aliens.

Tiger85: I'm not sure if I've ever seen them--I think I might have at, as you said, a zoo, but I'm not sure. I know my mom's been stung by them.

Ow, ow, ow! That sounds painful.

You're welcome!

Elena: It sounds disgusting . . . imagine swimming among those jelly-ish bodies. Eurgh.

Shaynie: Aren't they? :)

Old Kitty: It must have been!

Jellyfish are surprising animals, seeing as they're brainless and practically body-less, too. :P

I'll have to do something about that. Other people have commented that they can't see the images.

Michael: I've never swum in the ocean . . . but if I ever do, I'll certainly be doing my best to stay away from jellyfish!

John: I'm glad you liked the images!

The Golden Eagle said...

Hilary: It's always interesting to get another perspective on a subject! :)

I'll remember that advice, should I ever get stung.

Thank you! And same facts or no--jellyfish are such interesting creatures!

Ann: I hadn't known it either, until I read it in the Wikipedia article. It's fascinating, isn't it?

Yay for A-Z indeed! :)

The Writing Goddess: Writing and music? I'll definitely have to check out your post! It sounds great.

I must figure out a way to make sure the pictures appear . . . I don't know why my blog won't finish loading.

How cool that you get to see them so often!

Michelle: Thanks! :)

You're welcome--I love writing these science posts.

I've never touched one either, which I count as a good thing!

Sofie: Glad you like the new look! I thought it was getting a bit crowded, too--that's partly why I changed it. I also wanted a wider space for posts that could accommodate larger videos/images.

Ouch, that sounds painful!

Cool. I don't live anywhere near the coast, so I've never seen a jellyfish in its (semi)natural habitat.

Josh: A tank? Awesome! Those are so interesting to see.

I agree!

Ricky: Thank you!

I know I would have run for the shore! :P

Jerri: Especially some kinds of jellyfish. Moon, Mediterranean . . .

The Golden Eagle said...

Gary: You're very welcome! :)

Yup, the next letter is "K" . . .

LOL. I suppose it would make sense in some ways for it to be jellofish, wouldn't it?

Thank you so much for your comment!

The Words Crafter: For such simple animals, they're amazing complex!

I've been to the Chesapeake . . . but all I saw were dead horseshoe crabs and a few shells. :P

Alex: They are!

Alleged: They're a beautiful kind of jellyfish, especially the way they have the white 4-circle mark at the center of their bell.

Jemi: Like aliens, as L.G. said. :D

Kmckendry: I'm glad you enjoyed the images! :)

Trisha: Ouch! I wouldn't want to step on one of them.

Cindy: Wow.

I suppose the body would be the most vulnerable part--since it's so thin and flat, compared to the legs.

Niki: I've never seen Finding Nemo--at least not in its entirety. I stopped watching halfway once because I just didn't like it. :P

Cally: They used blue bottles as whips . . . ? Good grief. I wouldn't want to be on the receiving end of that. LOL.

Edith: It's amazing they way they're mostly water!

Carol: No consciousness, either, I supposed--no sense of where they're going or what they're doing except for nervous impulses.

Thank you!

Tomara Armstrong said...

I remember traveling to Galveston (TX) as a kid and not being able to swim because the jellyfish. Apparently, they have days when thousands of them are on the coast. They were all out in the water and many washed up on the beaches.

It was pretty cool. I am not a big fan of swimming in the ocean (ever since Jaws).

The Golden Eagle said...

It sounds like an intriguing phenomenon! Thousands of them all at one time? Wow.

I've never seen Jaws--after hearing so much about it, I'm thinking that's a good thing. LOL.

The Golden Eagle said...

Sofie: Oops . . . I just realized I read your comment wrong! For some reason I thought you said "two-column", not "three-column". Sorry about that.