Porifera is the phylum of which simple animals?

• A. Sponges
• B. Jellyfish
• C. Worms
• D. Sea urchins

Answer: (A)

Porifera refers to the simplest animals, which are sponges. They are multicellular but lack true tissues and organs, with porous bodies that attach to surfaces in water. Water flows through their pores, and specialized cells called choanocytes capture food particles, making them filter feeders. They don’t have nervous or digestive systems, and their support comes from spicules or spongin fibers. This basic body plan—no true tissues, a porous, sessile design, and filter feeding—defines sponges as Porifera. Jellyfish are cnidarians with tissues and radial symmetry, worms are from other phyla with more developed organ systems, and sea urchins are echinoderms with an internal skeleton, so sponges are the correct match.