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Fertilization does not occur only at the terrestrial level.
Even sea creatures, being living organisms, must reproduce.
To do so they developed their own methods of reproduction, sometimes similar to humans ones,
that allow them to survive in different environments.
A key example of the types of marine reproduction is that of spawning,
used by many aquatic species.
The two types of sea urchins, the Paracentrotus Lividus and the Arbacia lixula,
can easily represent this type of reproduction.
The male sea urchin, the Arbacia, releases male gametes in the form of *** in the marine environment.
These meet the female gametes of the female sea urchin, the Paracentrotus, in the form of eggs,
with which fecundation occurs.
Wanting to see how can born a new sea urchin, it is necessary first of all get him to release the gametes.
In the period of their maximum ripeness, will be enough to shake the hedgehog.
Otherwise you can give injections of chloride of potassium to the sides of the oral hole,
for the maximum of 1 ml, which stimulates the contraction of the muscles of the ***.
The *** appear to be whitish, eggs will be pink-orange.
You will need to divide them properly.
After obtaining the gametes, you need to place the female ones on a slide in the cockpit and add next to them
a drop of *** previously collected. The phenomenon of fecundation can be observed by
an optical microscope, even with a low zoom: cells fertilized will be surrounded by a kind of halo.
In these images, we note the division by mitosis of the first fertilized cell and the start of the segmentation phase.