Which of the following statements about cnidarians is incorrect?
Cnidarians have an incomplete digestive system with a single opening serving as both mouth and anus.
Ref: NCERT Class 11 Biology Chapter 4: Animal Kingdom Phylum Porifera and Cnidaria
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Cnidarians are best described as
Sponge aquiferous system illustrates increasing complexity and filtration efficiency from simplest asconoid with thin wall single central spongocoel entirely lined by choanocytes to syconoid where wall folded into radial canals increasing choanocyte surface to most derived leuconoid where choanocytes restricted to numerous small spherical chambers interconnected by network of incurrent canals bringing water from ostia and excurrent canals draining to osculum through thick mesohyl. Leuconoid maximizes choanocyte surface to volume ratio enables larger body size generates powerful unidirectional flow enhancing filtering capacity. Present in majority Demospongiae Hexactinellida and most freshwater sponges representing pinnacle poriferan filter-feeding adaptation for benthic ecosystems.
Ref: NCERT Class 11 Biology, Chapter 4: Cnidaria diploblastic radial symmetry; Campbell Chapter 33