RE: NANFA-- JellyFish

Nick Zarlinga (njz_at_clevelandmetroparks.com)
Wed, 2 Oct 2002 09:01:38 -0700

Casper, the freshwater jelly (Craspedacusta sowerbyi) are really neat
critters. There isn't a bunch of stuff known about them because unlike most
jellies, they spend most of their life in the hydra stage and only a few
weeks (as others have indicated) in the medusa (or "jellyfish") stage. They
are relatively difficult to keep in captivity and the way that most public
aquariums keep jellies is in a bare tank that has rounded corners. There
are two "standard" ways to design a jelly tank: either a Kriesel tank or a
cylinder tank. This is not to say that they can not be kept in other
systems, it is just that since jellies are planktonic, no obstructions is
the best way of keeping them. In both systems, the object is to keep the
animal moving in the current and most importantly to keep it away from and
intakes into the filter (a jet of water blows past the intake screen to keep
the jelly from being sucked onto the screen). A Kriesel tank is basically a
cylinder tank (or an oval shaped tank) that is on its side. It is usually
less than 18 inches from front to back. Also, for other jellies
especially, air lifts are a big no no. Air usually gets trapped under the
bell and can pose serious problems. I do believe that the fw jelly is the
only species found in freshwater, and finding the polyp stage is virtually
impossible. Medusa's usually bloom late in the summer and not every
year-there can be long periods of time when there are no medusa's around.
There have been aquariums that have worked with fw jellies but because they
are so short lived in the "jellyfish" stage, it is very difficult to keep an
exhibit going year round. Check out
http://microscopy-uk.org.uk/mag/artnov99/fwjelly.html for more information.

Nick Zarlinga
Aquarium Biologist
Cleveland Metroparks Zoo
216.661.6500 ext 4485

-----Original Message-----
From: owner-nanfa_at_aquaria.net On Behalf
Of Prizma_at_aol.com
Sent: Tuesday, October 01, 2002 2:48 PM
To: nanfa_at_aquaria.net
Subject: NANFA-- JellyFish

Mark Otnes and i were snorkling a nc mountain lake sunday and witnessed 10's
of thousands of pulsating jellyfish. translucent, varying in size from a
dime
to a quarter. they were found at the conjuntion / outflow of a rushing clear
cold mountain stream... 58 degrees and mixing of the much warmer lake's
greenish water. where the waters mixed it created a odd funhouse glass
effect
on your vision from the temperature difference. very unusual. this is my
third time to witness these freshwater jellyfish. all 3 times have been on
mountain top manmade lakes. the second time was at the ohio meet. the first
in a lake on lookout mountain while canoeing.
does anyone know information about these? how did they get into manmade
lakes
that use to be mountain streams? odd. but very enchanting, very mezmerizing.
i brought about 1/2 dozen home in a pop bottle but they were dead this
morning. :( i was hoping to introduce them to my cement pond and further
observation. i know jellyfish are extremely difficult to keep and require
circular flow aquaria, no corners.
any knowledge or experience out there?
casper

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/"Unless stated otherwise, comments made on this list do not necessarily
/ reflect the beliefs or goals of the North American Native Fishes
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/ This is the discussion list of the North American Native Fishes Association
/ nanfa_at_aquaria.net. To subscribe, unsubscribe, or get help, send the word
/ subscribe, unsubscribe, or help in the body (not subject) of an email to
/ nanfa-request_at_aquaria.net. For a digest version, send the command to
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/ For more information about NANFA, visit our web page, http://www.nanfa.org