If you were a sea turtle, what would your favorite sandwich be? Peanut butter and jellyfish! Each of the seven kinds of sea turtles eats jellyfish at some time in their life and the 7-foot- long Leatherback mainly eats jellies.
Jellyfish are not fish at all, but rather are invertebrate in the group of animals called Cnidarians. This group also includes corals and anemones. Their name comes from the Roman word for nettle, a plant that can sting. The most venomous jellyfish is the Box Jelly of Australia. Other jellies don't sting at all. Instead they capture their prey with sticky tentacles.
Fossils of jellyfish date back 500 million years, making them the oldest know multi-organ animal, which is pretty good for an animal without a backbone and made mostly of water. You might think that jellies are only found in the ocean, however freshwater jellyfish can be found worldwide and in all but six of the 50 states. Jellies have even been seen in small lakes and ponds in most of the counties of Pennsylvania. Dr. Terry Peard of Millersville University is an expert who studies freshwater jellies.
At Carnegie Science Center we have upside down jellies, named because they keep their tentacles facing up toward the light, in our Mangrove tank. This action keeps the algae living there so healthy it produces extra sugars, which the jellyfish can then use as food. Because of this, their sting is fairly mild (I know from experience!); as they don't have to rely on killing small animals to eat.
If you are interested in seeing jellies, come to Carnegie Science Center or search our local ponds and lakes. You could go to an Asian grocery store and buy tasty, pickled jellyfish to eat. You might even try some with peanut butter, like a sea turtle would, if they ate sandwiches.