Their purpose is reproduction.
Pond water contains a variety of plant and animal life. While some are visible to the plain eye, others require a microscope to observe them. For example, there's bacteria, protozoa, hydras, algae, and arthropods. You will have the opportunity to see a number of microorganisms from both the plant and animal kingdom.
This property allows fish living in lakes and ponds to survive the winter. The ice that freezes on the surface insulates the water below so it stays warmer! In general, it is extremely unusual for the solid phase of a substance to be less dense than its liquid phase, but lucky for aquatic life it is!
The answer is <span>motor neuron. Hope this helps!</span>