The roundworm body cavity is pseudocoelomic, whereas the planarian body cavity is acoelomic.
the most important to the survival of the ecosystem is sunlight
Answer:
Are you referring to symbiotic relationships between organism? If so, the answer would be parasitism.
One organism, a parasite, takes advantage of another organism at the expense of the host organism.
Ex. A tick bites a dog for blood to use as food. The dog gets an uncomfortable bug bite and the dog might catch a tick borne disease.
Biosphere. Bio means life, and Biosphere means ALL life on earth.
