Waterfleas (Dapnia) is an often used basic live food in aquaria.
They are up to half a centimeter big an have a jerky movement
through the water hence the name waterflea.
Daphnia eat free floating algae (phytoplancton) and bacteria.
They are eaten themselves by most of the freshwater fish ,salamanders,
hydra and
waterinsects.
Reproduction
Daphnia reproduce most often by by parthenogenicity, and bearing,
on average, ten live young per individual during summertime.
During this time the entire race is made up of females . At the end
of the summer, and when food become scarce males develop, and
the females produce eggs that must be fertilised
a hunter for Daphnia glassworm
The body of the glassworm is totaly transparant.
feeding
During the time that the waterflea goes down it feeds
on the algae.Movements of its short thoracic legs aid in
filter feeding.
waterfleas and fishes
Waterfleas are easy targets for fishes. But waterfleas change there behaevior if
fishes are a problem. If waterfleas smells fishes, they hide themselves
between waterplants. But in the abscence of fishes they spread through the water.
They are attracted to light, in the dark they sink to the bottom.
Cultivating Daphnia's
Best way to start is placing a transparant bucket outside the house.
add a very small of fertilizer.
Wait two weeks and until the water gets green, then add some daphnia.
Thats enugh for a daphnia reproduction explosion.
They eat the all algae in the water wich gets transparant again.
more and faster daphnia's
Take a transparant basket, this will improve the growth of algae.
Snails will reduced the amount of algae on the transparant side of the basket.
Keep the water circulating by using an air pomp, producing big bubbels,
(so dont use oxygenblocks).
A small amount of a fertilizer (like Miracle grow) will improve algae growth.
Yeast can be given as a food for the daphnia.
Problems
Its rare when a daphnia culture doesn't grow as it should. The most important
reason for this is the growth of the hydra
Mosquito's (culex pipiens) will use youre basket for reproducing, and you can give
those mosquitolarvae to youre fishes. Raising Daphnia in this way has
some big disadvantages: The amount of daphnia is big , but the water
gets polluted and acid. You have to start over the cycle again.
Daphnia anatomy
The first antennae are small, but the second pair is large and designed for swimming by powerful, jerky strokes.
Waterpollution
Daphnia are extremely sensitiv for metal-ions. For these purpose they are used as
indicators for polution. On the other hand , there is very little sensitivity for
changes in temperature.
Temperature
Although waterfleas are not very sensitive for temperature changes,
they stop growing ar 30C.
Other tiny watercritters
cyclops and diaptomus live, eat and are hunted in the same place as daphnia:
Daphnia and Copepods have a different strategy
Although they eat the same stuf (They filter) free flaoting algae,
have the same size, live on the same place and are eaten by the same animals,
they have a different survival strategy:
Daphnia: r-strategie: a short live, (three months) with a very fast
development, lots of eggs and offspring
Copepods: K-strategie: slow development, more advanced, less eggs
female daphnias with egg's, foto made by webcam
An improved Daphnia Factory
To produced daphnia in a predictable way one need two aquaria:
a large one , filled with green water, and a small one, containing
the daphnia.
The green water is pumped up by an airbubble lift into the second
aquarium were the algae feed the waterfleas. The water leaves
through an outflow filter, to prevent the daphnia form entering
the first tank, otherwise they would reduplicate explosively.
The greatest disadvantage of this two-tank approach is the
filter that get easely obstipated by algae and need to
be cleaned montly. Daphnia produced this way are very cheap,
clean and without pollution or parasites.
You need a airbubble lift, as an electrical pump wood kill the
algae by its propellor. An airbubble lift is a tube in which air
is pumped at the underside of the tube. The airbubble produces
a flow of water to the upperside of the tube. The airpump is the
same (membrame)pump as used in aquaria,
Commercial daphnia
Daphnia is produced in the last stage of a wastewater treament plant.
The daphnia that grow here are abundant and cheap. But these Daphnia
are polluted with heavy metals. Another way to collectyed is by boat
on a lake, but these Daphnia carry parasites like the Leeches.
