What Exactly Is a Jellyfish Anyway?
Posted by Greg on September 26, 2011
Ever run (or swim) into a jellyfish? I have. When we lived in Virginia we would occasionally get a bumper crop of them in the Chesapeake Bay and along Virginia Beach. I found out why these particular jellyfish are called sea nettles, because they feel just like the stinging nettle grass we had along the lagoons and waterways around Lake Monona, Wisconsin when I was a kid. They can interfere with an enjoyable swim or, more recently, an attempt to swim the straits between Cuba and Florida. Actually, that was a Portuguese Man-of-War, which turns out not to be a jellyfish at all.
So, from the National Park Service: “Jellyfish are related to other creatures, such as sea anemones, corals, and hydroids. All of these creatures use stinging cells for feeding and defense. With no brain to guide their actions, jellyfish must depend on currents to carry them to where food may be. Spring and summer winds and currents can sometimes cause many jellyfish to wash onto the beach at the National Seashore.” (Padre Island)
Here are a few examples of sea jellies and jelly-like organisms:
Moon Jelly: “Moon jellies are clear, fragile swimmers that propel themselves through the water by moving their bell in a waving motion. Four horseshoe-shaped markings in the center of its bell are its distinguishing characteristics.”
Cabbagehead Jellyfish: “The Cabbagehead jellyfish moves along like a bulky, milky-colored bell. Unlike the Moon jelly, the Cabbagehead jelly’s bell lacks long tentacles, but has short oral arms that extend below the bell.”
Sea Nettle: “Like the land plant which shares its name, the Sea nettle packs a powerful sting. Several long tentacles dangle from the edge of its bell, and four long arms are suspended from the center of the bell.”
Comb Jelly: “Comb jellies, lacking stinging cells and having a complex digestive system, are not true jellies.”
Portuguese Man-of-War: “The Portuguese man-of-war is sometimes referred to as the “blue jellyfish,” but it is actually not a true jelly. Instead, it is a colony of hundreds of animals that live and work together as a single unit. Each type of animal forms a different part of the body with one of four specialized jobs.”
These excerpts come from “Sea Jellies and Jelly-like Organisms“, a National Park Service brochure. It has quite a bit of fascinating information on what we layman would call a jellyfish, but might not be (i.e. the Portuguese Man-of-War). And, by the way, the photos are awesome.
However bothersome they may be when you’re swimming with them, jellyfish can be fascinating and beautiful to view in the safety of an aquarium. We have seen some beauties in the aquarium here at the Albuquerque Biopark. Mesmerizing. Watching jellyfish in an aquarium tank is like watching a lava lamp!
This entry was posted on September 26, 2011 at 6:34 AM and is filed under Beach and Coastal Wildlife, Monday Miscellaneous. Tagged: Blue Button jellyfish, by-the-wind sailor jelly, cabbagehead jellyfish, Chesapeake Bay jellyfish, comb jelly, moon jellyfish, Padre Island jellyfish, Portuguese Man-of-War, Sea Nettle Jellyfish, What is a jellyfish?. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.
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