Asexual reproduction in brown or green hydras is usually done by budding. Side shoots, at various stages of growth, are commonly seen attached to the mother hydra and soon stand out.
This multiplication process, in which no genetic variability occurs, is conducive to stable environments and favorable times of the year, when hydras are well fed.
Hydra is hermaphrodite. Some testes and only one ovary are formed, especially at unfavorable times of the year, from undifferentiated cells in the body.
The only egg produced is taken from the ovary. The sperm are released into the water and go looking for the egg. Fertilization occurs in the body of the hydra. The zygote formed is surrounded by a thick chitinous layer (of consistency similar to the insects' chitin skeleton) and, after some developmental time, the embryo, enclosed by the protective shell, detaches from the hydra's body and remains within the shell during all time unfavorable.
With the arrival of the favorable season, the bark breaks and a small hydra emerges that grows to adulthood. There is no larva. The development is straightforward.