Traditional culture method of Clytia hemisphaerica.


  • 5 liter glass beaker
  • Artificial or natural sea water (see more detail in Sea Water page)
  • Motors (5~6 rpm, 12 or 24 volt)
    • Motor mount: to fix the motor on the beaker.
  • Power supply (AC adaptor)
  • Pedal (about 5 cm x 10 cm plastic plate)

    • It is recommeded to use disposable materials for making pedals so that you can change to new pedals if it is highly contaminated with algae. We make them with transparent plastic casing of “Grainer Bio-One EasyLaod micropipette tips” and disposable “pastette”.
    • Soft silicone tubes to connect the pedal to motor

  • Dish (φ10 cm x 5 cm)
  • Glass pipte (φ 10~12 mm) to transfer medusae

Setting up

Common tank set up
A tank consist of a 5 liter beaker, slow speed motor, a plastic plate (pedal) connected to the motor with a silicone tube.
Put hot water in the beaker and leave it one to two overnights to get rid of remaining chemicals for manufacturing when you use it for the first time. The motor and the pedal are to make constant water current, which is necessary to keep medusae swimming all the time and critical for them to alive. It is recommended to use low-voltage motor (12 or 24 volts) with gears to reduce the rotation speed to 5~6 rpm. Motor should have power cable and appropriate (hopefully water-resistant) connector to power supply. Each tank should have fixed volume of sea water to check evaporation easily. For example, 3.5 liter of sea water is put into 5 liter tank in Villefranche laboratory. Put motors on top of the beaker and connect pedals to motor so that pedals mix sea water slowly and continuously. Adjust the hight of the pedal by changing the length of silicone tube. We normally adjust it to come to near the surface of sea water.

Configuration for Jellyfish (Medusae)

Only and most importent point for jellyfish is the density. You can grow a few to several hundreds of baby medusae (up to a few mm in diameter) in a tank. For bigger baby jellyfish (4~5 mm) the number drops to 100~200. 80/tank is maximum for young (but immature) jellyfishes with diameter up to 10 mm. For adult jellyfish, it is highly recommended not to exceed 40 in a tank and 30/tank is ideal. This number is determined so that all jellyfish can catch food without making the sea water dirty at least 3~4 days. Jellyfish growth seems to be affected directly by the density. This is because jellyfishes don't grow even we feed enough and change sea water often, if there are too many in a tank.To transfere meduse to the tank, use a glass pipette for large medusae or plastic pipette (similar to pastour pipette) for smaller medusae. Medusae - especially adult - are fragile and it is not recommeded to add water to a beaker which contains medusae already, despite they are strong enough to resist the pipetting.

Configuration for Colony

Transplanting a colony to a new beaker

Colony is sessile form of Clytia and normally stay on solid materials such as inner wall of the glass beakers. You can easily split colonies as a cut of polyp, which then attach to its new habitat. Cut existing polyps at the bottom of the vertical stolon using scissors and wash in a glass dish by pipetting to get rid of algae and protozoans as much as possible.
Add 500~1000 ml of sea water in a new beaker and put 5~10 polyps (numbers depend on strain) in it. Try to disperse polyps in the tank. Then leave the tank at least 1 nights (for healty strain) or up to 3 days (weak strain like Z4C2). Don’t touch the beaker while you wait them to attach to the glass.

Once They attached…

Once they attach to the beaker, set up temporary culture system. The polyp cuts attach very weakly to the glass therefore there is no need to add sea water. Set up the motor and pedal so that only several millimeter of the pedal is immersed to sea water. Feed on them artemia. Try to reduce artemia as little as possible because the sea water can’t be changed when the polyp is newly attached. It is also recommended to flash artemia directly nearby the polyp using a Pasteur pipette. Polyp will be stably adhered to the glass within one week. Then you can wash or change sea water like as the existing polyp colonies.