alleryWhich of the following phyla is characterised by radial symmetry, diploblastic organisation and the presence of cnidoblasts?
ACoelenterata
BPorifera
CCtenophora
DPlatyhelminthes
Answer & Solution
Correct answer: A. Coelenterata
1. Radial symmetry appears in Coelenterata, Ctenophora and Echinodermata.
2. Diploblastic organisation with ectoderm + endoderm is exclusive to Coelenterata and Ctenophora.
3. Cnidoblasts (cnidocytes containing nematocysts) are diagnostic of Coelenterata (Cnidaria) alone.
4. Ctenophores use ciliated comb plates and lack cnidoblasts.
_Source: syllabus Biology, Ch 4 "Animal Kingdom", §4.2.2_
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