Q.94. Which ONE of the following phyla have choanocytes?
(A) Ctenophora
(B) Nematoda
(C) Cnidaria
(D) Porifera

Choanocytes, also known as collar cells, are specialized flagellated cells unique to the phylum Porifera, enabling water flow and food capture in sponges. The correct answer to the question “Which ONE of the following phyla have choanocytes?” is (D) Porifera.​

Correct Answer: Porifera

Porifera, commonly called sponges, feature choanocytes lining their inner chambers. These cells have a flagellum surrounded by a microvilli collar that creates water currents for filter feeding and nutrient uptake.​
No other phylum in the options possesses these characteristic cells, making Porifera the exclusive match.​

Option Breakdown

(A) Ctenophora

Ctenophora, or comb jellies, use colloblasts on their tentacles for prey capture, not choanocytes. These adhesive cells differ structurally and functionally from sponge collar cells.​
They lack a porous body plan and rely on ciliary combs for locomotion.​

(B) Nematoda

Nematoda, roundworms, have a pseudocoelom and complete gut but no choanocytes or filter-feeding cells. Their body is covered by a tough cuticle, adapted for parasitic or free-living lifestyles.​
Excretory systems involve renette glands, unrelated to collar cells.

(C) Cnidaria

Cnidaria, including jellyfish and corals, possess cnidocytes with nematocysts for stinging, not choanocytes. These explosive cells handle defense and prey capture, contrasting Porifera’s passive filtration.​
Their diploblastic body lacks the complex canal system of sponges.