Movement
The water in which they live provides the
medium of transport. The medium passes
through definite body channels and may be
propelled by cilia, flagella, or muscular activity.
Respiration
There is not structural specialization,
but rather a process of diffusion between
the cells which lay at the surface of the
water and the cells of the cnidaria.
Protection
There are two layers to the skin of the
cnidaria, the ectoderm and the endoderm.
Support
The skeleton is an outer layer of tough, transparent
perisarc. It supports and protects the cnidaria.
Circulation
Circulation occurs through the movement
of fluid between two tissue layers
(ectoderm and endoderm)
which circulate the food to each cell.
Reproduction
Reproduction is sophisticated.
The two generations are the hydroid and
the medusa. The hydroid reproduces
asexually; its offspring is the medusa.
The medusa reproduces sexaually;
its offspring is the hydroid.
Pinegreenwoods Montessori
Montessori Zoology
