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weisswasser
Crustaforum-Team
Age: 29
Joined: 23 Jan 2006
Posts: 59
Location: Sasbachwalden
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Reproduction of fresh water shrimps
The reproduction of the fresh water shrimp starts with the so called "ovum stain" which is produced by female shrimps. It's the ovaries in which the eggs are produced and depending on color as well as the type of shrimp it is recognizable as a dark, yellow, green, or other discoloration in the neck (carapax/abdomen). As soon as the eggs are sufficiently developed (after about 4 weeks), the female shrimp will shed its skin and at the same time surrenders pheromones to the water.
Attracted by the pheromones, the sexually mature males will flutteringly swim through the water to look out for the mating female. This behaviour is also termed as "mate-swimming".
As soon as the male shrimps have reached the female, the proper mating act, which seems to be more of a wild scrimmage, beginns. The males now overrun the female and each prospect is endeavored to take in the most favourable position. Not very amused about this hoydenish attack the female shrimp tries to get rid of the males by flipping around and furiosly whaming her tail. Soon after a while, the situation quitens down and the winner will copulate the female by sliding along side. With his first two pairs of pleopodens (which make up the copluation organ) he now attaches a slipcovered sperm package (spermatophore) on to her genital opening located right between the striding legs.
After copulation the male usually backs away from the fresh skinned female which will now look out for a safe place to hide and after some time passed by it will press the eggs through its genital opening. Thereby some scent will be released which helps dissolving the colloidal slipcover of the sperm package thus fertilizing the eggs.
Using the striding legs and by means of sticky secretion, the eggs will be fixed into a special spawn pouch near the swimming legs. From now on the female shrimp practices breeding care. Rythmic fanning of the swimming legs provides the clutch of eggs with sufficient oxygen.
The gestation of all dwarf shrimps depends on the water temperature as well as the type of shrimp. Usually it takes about 3-4weeks.
Until hatching this procedure is alike to all kinds of dwarf shrimp.
Because of the different states of development, we distinguish between two types of reproduction:
Specialized type of reproduction:
Depending upon the kind, 20 to 40 fully developed shrimplets will hatch and instantly be independent. In a well running tank they will find enough food to grow but can be fed with finest food at the same time too.
The juveniles will be sexually mature after 4 to 6 month and about 1,5cm of size.
Primitive type of reproduction:
The female shrimp carries up to a thousand of tiny eggs, from which afloat larvae will hatch. These larvae pass through different stages of development until they give up their plankton being and start to actively nourish.
The larvae of some species though (like caridina japonica and atyopsis) need brackish- or even saltwater to develop. In their natural environment they will be released into the sea as plankton and return back into fresh water after metamorphosing into a fully completed shrimp.
written by Lidija – german version: http://www.garnelenforum.de/ftopic1026.html
translated by Claudine ~ weisswasser |
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Kind regards,
Claudine |
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