Thursday, August 19, 2010

Freshwater Jellies: They Didn't Escape From The Tennessee Aquarium

Tennessee Aquarium visitors are mesmerized by the gorgeous jellyfish species on display in the Ocean Journey building. Jellies: Living Art is a joint exhibition with the Hunter Museum of American Art. Six species of jellies are showcased alongside the stunning works of four artists whose studio glass was inspired by nature. These pulsing animals are saltwater creatures. But did you know there are some FRESHWATER jellies right here in Chattanooga?

Senior aquarist Sharyl Crossley takes care of the jellies at the Tennessee Aquarium. She had a fun adventure recently, snorkeling just north of Chattanooga in search of freshwater jellies.
Her pictures of these delicate beauties remind us that there is a surprisingly diverse community of life in our lakes and streams.

Here's what our resident jellyfish expert has to say about these little-known native creatures.
Crossley: "The scientific name for this species is Craspedacusta sowerbyi. The family that these jellies belong to is Oliniidae. Commonly they are usually referred to just as freshwater jellyfish, but an alternate name that I have also seen is peach blossom jellyfish. They are in the Cnidarian phylum (Class Hydrozoan – like the Aquarium's umbrella jellies.)
"Should people be afraid of being stung by these local jellies?"
Crossley: "They do possess stinging cells, however their stingers are quite small and typically do not bother humans. They feed on small freshwater plankton (i.e. daphnia and copepods).

"Where can freshwater jellyfish be found?"
Crossley:"These jellies are pretty common, but because of their small size (an adult is about the diameter of a dime), clear bodies, and short life span – you usually have to be in the right place at the right time and be observant to spot them. Their normal habitats include calm streams/rivers, lakes, ponds, and flooded rock quarries. They have a global distribution and been found in almost every state in the U.S., as well as across Europe, Asia, Africa, Australia, Canada, and Central America. They are believed to have originated in China.
"When can peach blossom jellyfish be seen here?"
Crossley:"They seem to prefer warm water and are therefore only found during the summer months here in Tennessee. I usually start getting phone calls from local fisherman that spot them in mid July until September. The medusa seem to be short lived (2-4weeks maybe) so I would guess freshwater jellies in our area produce more than one bloom of medusa each summer. In tropical areas, where the weather stays warm year round, these jellies can probably be found intermittently through out the year.”

"Will we be able to see peach blossom jellies at the Aquarium?"
Crossley: "I have collected some in the past to try to start a culture, but without much success. I would like to try again, but haven’t had time to create a suitable holding system for them. According to literature on this species, the biggest hurdle to culturing freshwater jellies may be that the majority of freshwater jelly populations found in the United States are either all male or all female - making sexual reproduction (typical method used to start jellyfish cultures in captivity) almost impossible. A culture could be started using asexual methods, but that would require finding the polyps in the wild. The polyps are typically solitary and quite small, so looking for them is like looking for a needle in a haystack…in a field of haystacks.”
Well, at least we got to see these pictures. (Taken by senior aquarist Matt Hamilton on the same snorkeling trip.) Thanks Sharyl and Matt for sharing them and giving us some great information on these interesting animals.

No comments: