Question

Who is microscopic animal breathe through its body surface?

Answer 1

because while breathing through body surface include diffusion process and so is slow and also smaller level oranganism don't need much or instant energy

Answer 2

Microscopic organisms breathe by the process of diffusion as they do not have any respiratory organ. So, they breathe by their general body surface. ... If an animal is small enough, it does not need any specialized structures for breathing — oxygen enters from outside and CO2 dissipate to outside by osmosis.