Benthos describe organisms that live on or in the ocean floor.
Answer:
Porifera—gastrovascular cavity, coelomate.
Explanation:
Sponges do not contain digestive system but obtain nutrients through the diffusion process. Porifera is the most commonly asymmetrical in nature but can also have radial symmetry. Porifera has no coelom.
Lacking a true digestive system, they depend on the intracellular digestive processes of their choanocytes for their energy intake. Gas exchange, circulation, and excretion occur by diffusion between the water and the cells.
Algae live in bodies of water and damp places and are commonly found in both aquatic and terrestrial environments. Terrestrial algae mostly live in moist, tropical areas. They prefer wet places, because they do not have vascular tissues and the other necessary adaptations to survive on land.