Jellyfish range from less than an inch to up to 7 feet in diameter, and the largest jellyfish have tentacles over 100 feet long. The jellyfish exist in every single major oceanic area of the world, residing in shallow coastal areas to over 12,000 feet deep. They're everywhere!
They don't have a brain:
That's right. Jellyfish don't have brains. They aren't predators attacking us intentionally; the big bad jellyfish isn't going to come after you. What they have is an elementary nervous system that gives them basic responses to stimuli such as light and odor, enough to just feed and exist. The jellyfish radial symmetry allows them a 360 degree sensory system, so you won't be sneaking up behind it!
How do they even eat?:
Jellyfish have a mouth at the base where tentacles are. The tentacles capture prey and push it into the mouth. Jellyfish have a simple digestive cavity, stomach, and intestine, exiting food from the anus. The jellyfish are part of the phylum Cnidaria, having similar relations to others of the same animal grouping such as sea anemones, sea whips, and coral. ¹
They're coming at me!?:
Jellyfish have very limited control over horizontal movement. The ocean current, tides, and wind provide the horizontal movement. So if you see a jellyfish, it's not going to come up to you and sting you, you probably have to run into it. Jellyfish are able to make vertical movements, bobbing up and down. This is because of their sensitivity to light, going deeper while the sun is high, and closer to the surface at other times. ¹
How do they sting?:
Not all jellyfish are venomous to humans. The sting comes from the tentacles of the jellyfish which is embedded with nematocysts. Nematocysts are activated on contact and inject toxin into its prey, generally paralyzing it. Most of the jellyfish species off the southeastern coast only inflict mild stings. However, the majority of stings occur in tropical and warm waters. ¹
Types of Jellyfish:
There are several types of jellyfish, some harmless, some venomous. If you're out there, you might want to look at the different types and recognize which one you should avoid.
This Jellyfish Species List gives a list of all the species with a detailed description and image. Try looking up what types of jellyfish is local to the vacation area, and then looking it up. ²
---------------------------------------------------------------------------
Resources:
¹ Jellyfish by the South Carolina Department of Natural Resources
² Jellyfish Species by Nathan Dickerson
No comments:
Post a Comment