Daphnia, commonly know as Water Fleas are micro-crustaceans. Daphnia are a text book species ideal for investigations into physiology as their bodies are transparent meaning students can clearly see their internal organs. Daphnia reproduce both sexually and asexually producing a clutch of eggs each time they moult. Daphnia are filter feeders meaning students can watch the movement of food through the gut. Other investigations include looking into the effect of caffeine or temperature on heart rate.
Once you receive your Daphnia decant into a clean tank/jar and keep out of direct sunlight at around 21°C (room temperature) Daphnia can survive like this for 3 to 4 days without further care. If you intend to keep them for longer, transfer into a clean tank (ensure no detergent residue remains) filled with rain water or tap water treated with a dechlorinator and feed with a pinch of dissolved yeast every 1-3 days (depending on number of Daphnia). The yeast encourages bacterial & algal growth which the Daphnia then feed on. Avoid overfeeding - the Daphnia should clear the water within 8 hours, if they don't, reduce the about of yeast fed. Every week or 2 change about 1/3 of their water but do not clear the debris from the bottom of the tank as it may contain eggs.
During the winter we have to be careful not to over deplete our tanks, consequently there may be delays in sending as we try to spread orders out.
250g gives around 150 Daphnia, 500g around 300.