Dutch: kikkervisjes
Every spring I collect frogspawn from the pond. It is a real pleasure
to watch the development or metamorfosis into a frog or toad
Frogspawn can be found in the shallow sections of a pond.
There are four stages in the development:
Frogspawn stage
First Week
The embryos turn around in their eggs, which can clearly be seen
through the transparent shell. The yoke (he transparant jelly) is slowly
used up and a hole appears in the shell through which the new tadpole
can escape. Eggs that don’t develop become opaque or grey.
A symbiosis with the algae
First Week
Algae grow in the wall of the eggs. When the aid of sunligh the
spawn rises because if the production of oxygen. When it is dark the
spawn sinks back to the bottom. This is actually a form of symbiosis between
the algae and the spawn with advantages for both the spawn and the algae.
By rising to the surface there is less chance that the frogs-spawn will get
eaten by a salamander or fish
The algae are also food for the tadpoles. The advantage for the algae
is that they get nutridients from the tadpole.
Almost all the other creatures in a pond eat frogspawn, like
sticklebacks, salamanders, fresh waterlobster ,waterinsects eat frogspawn.
Various stages of frog embryos: Left and to the front still
completely rolled up. To the right you can distinguish the head
,body and tail. On the wall of the egg you can see the first
algae colonies, which will later cover the whole egg supplying
oxygen and nourishment. Edible frog and brown frogs search
for shallow water, which smells of algae so that they are sure
of food for their tadpoles.
When the tadpoles come out of there eggs
they lie on top of the spawn and stay there for a little
before they sart swimming. In this stage they are very
vulnerable and breathe with heire gills.
tadpolestadium first month
Mainly a head with a tail :you can see there external gills.
They get most of their oxygen through their gills and a little through
their mouths. The tadpoles like to eat the algae on the waterplants.
Tadpoles have the tendency to conceal themselves in duckweed.
They feed then on the plankton algae, which floats just below
the surface. This is called neuston. If you want to keep a tadpole
put a big pot of water outside in the sun for a little while and the
algae forms automatically. You can feed them with boiled lettuce,
they'll love it! The tadpoles are eaten
by almost all of the other pond predators like salamanders,
freshwater lobster, shrimps and waterinsects, fish etc.
As a defence to discourage mainly larger fish some sorts are poisonous.
Problems raising tadpoles:
The biggest problems are the result of overpopulation:
- The water gets cloudy or msty , ths is due by bacterial growth.
Often because there are dead frogfishes. Chance the water.
- The tadpoles stop there development, no legs appear,
they stay small: this happen when there is a lack of food.
Give fishfood or waterplants.
- Floating on the surface: there is shortness of oxygen in
water , or the water is to acid: change the water or the
temperature s too high.
Solution: bring the most of youre tadpoles back to the pond.
Add waterplants: they produce oxygen, filter the bacteria out
and are food for the frogfish. change the water. a low
temperature is better for almost everything.
Remember that in the nature 99.7% of the tadpoles never make it.
Four legs and a tail
First month This is a difficult stage because the tadpoles are changing.
The gills disappear and they have to come to the surface to breath.
Also their eating habits change : they start eating other small water animals,
cadavers and sometimes floating fish food. When their front legs appear
they stop feeding and digest their own tail.
Artifial feeding: Give red mosquito larvae
otherwise cannibalism creeps in.
Eventually the tail disappears to a small point.
