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Two hydra's with some developing buds , soon the will separate
and start there own live.

The Hydra fusca on the snailhouse of Wandering snail or
Lymnaea peregra. Both foto's are made by Jaap Cost budde

-1 two red watermites
-2 Cristella mucedo, a a bryozoan.
-3 Hydra
-4 Piscicola, a leech.
-5 Branchipus schaefferi, a fairy shrimp
-6 Plumatella, a bryozoan.
-7 Apus, a arthropod
-8 Planorbis planorbis, a snail
-9 Stickelback
-1 Duckweed
-2 Frogbite

The freshwater green hydra in a bottle
A photo made by Jaap Costo Budde

Green hydra

The the freshwater polyp Hydra viridissima
or Green Hydra lives in symbiosis with algae of
the Chlorella group (zoochlorella), unicellular
green algae, who can hardly survive outside the
body of hydra viridens. They provide the polyp
with food and the green color to help the polyp to
camouflage itself, in exchange for nutrients
and protection. When the Hydra reproduces, it
transfers Chlorella cells to its eggs,
ensuring its offspring start life with the
algae already on board. The Hydra viridens or green
hydra is the most often seen freshwater polyp.
This green hydra is hermaphroditic, meaning that
male and female organs (gonads) are located
on the same animal.


    A polyp living in small waters like ponds. Its catches
    its prey by using its tiny stinging cells located in the
    tentacles. After paralyzing its prey the tentacles bring
    the prey to the mouth and ingeste it.Hydra is a solitary
    freshwater invertebrate animals belonging to the order of

    the duckweed jungle

    The hydra is the biggest killer in the duckweed jungle.
    It's tentakels are hanging down from the roots of the
    duckweed. There it waits until it can catch its pray,
    mostly water flees ,diaptomus and cyclops .
    Even small fish and newts and tadpoles can be
    catched by polyps.But of course the polyps are eaten
    themselves to,mostly by the stickelbacks and snails.

    At the top :Hydra fusca.
    In the midden: Hydra grisea with buds.
    right onder it: this hydra but contracted.
    Left at the bottom: Cordylophora Lacustris.
    Right at the bottom: the green Hydra Viridissima.

    Anatomy of an green hydra:
    The outermost layer is called ectoderm
    and contains the nettle cells, with the
    highest density on the tentacles.
    The covering of the gastrovascular
    space is called ectoderm, also containing
    the reproductive organs.
    The layer in between house the
    zoochlorelles, algae that lives in symbiose
    with the green hydra.

    the control of Hydra

    Green hydra can easely become an pest in youre
    aquarium: its ugly, it clouds the windows, it feeds
    on the live food.
    Green hydra appear in aquaria
    were living food is used, especially waterflea's and
    artemia. It doesn't help to clean the windows
    of the aquarium, hydra's regenerate completely.
    Have a look at these alternativs:

    1. Don't feed the fish with living food: this will give
    a quick result but the hydra's have laid eggs.
    2. Change youre living food , change daphnia or artemia
    in bloodworms.
    3. heat the water of the aquarium up to 42 degrees Celsius
    of course you first have to evacuate the fish. This is called
    the "Vienna method"
    4. Some fish love hydra, they eat them: black molly,
    labyrinth fish, swordfish.
    5. Stickelback and the great Pond snail re great natural
    hydra hunters.
    6. Flubendazol (Flubenol 5% / 2g per 100 l water) is very effective, but kills youre snail as well.
    it resolves very slowly in the water.

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