Phylum Ctenophora: The Comb Jellies
Phylum Ctenophora, placed right after the cnidarians and just before the flatworms, is a short lesson packed with examinable facts. The comb jellies or sea walnuts are exclusively marine, radially symmetrical, diploblastic animals with a tissue level of organisation.
In this quiz you will test your grip on the decisive characters of the phylum:
- Eight external rows of ciliated comb plates that drive locomotion
- Digestion that is both extracellular and intracellular
- Well-marked bioluminescence
- Sexes not separate, reproduction only by sexual means
- External fertilisation with indirect development
- Classic examples: Pleurobrachia and Ctenoplana
Work through the fifteen questions carefully and read each explanation — every one of them is a comparison point against Cnidaria and Platyhelminthes.
Q1. Ctenophores are commonly known by which of the following popular names?
The lesson states that ctenophores are commonly known as sea walnuts or comb jellies.
Q2. Which statement correctly describes the habitat of ctenophores?
Ctenophores are exclusively marine organisms, as stated in the lesson.
Q3. The symmetry of ctenophores is best described as:
Ctenophores are radially symmetrical, unlike the bilaterally symmetrical flatworms studied next.
Q4. With respect to germ layers and organisation, ctenophores are:
The lesson describes ctenophores as diploblastic organisms with tissue level of organisation.
Q5. How many external rows of ciliated comb plates are present on the body of a ctenophore?
The body of a ctenophore bears eight external rows of ciliated comb plates.
Q6. The eight rows of ciliated comb plates in ctenophores are chiefly responsible for:
The lesson clearly states that the comb plates help in locomotion.
Q7. The mode of digestion in ctenophores is:
Digestion in ctenophores is both extracellular and intracellular.
Q8. The property of a living organism to emit light, well-marked in ctenophores, is called:
Bioluminescence, the property of a living organism to emit light, is well-marked in ctenophores.
Q9. Which of the following is true about the sexes in ctenophores?
The lesson states that sexes are not separate in ctenophores.
Q10. Reproduction in ctenophores takes place:
According to the lesson, reproduction in ctenophores takes place only by sexual means.
Q11. Fertilisation and development in ctenophores are characterised by:
The lesson states that fertilisation is external with indirect development in ctenophores.
Q12. Which pair of examples is given in the lesson for Phylum Ctenophora?
The examples cited for Ctenophora are Pleurobrachia and Ctenoplana; Taenia, Fasciola and Planaria belong to Platyhelminthes.
Q13. In the course sequence of the animal kingdom, Phylum Ctenophora is placed:
Ctenophora is conventionally placed directly after Phylum Coelenterata and directly before Phylum Platyhelminthes.
Q14. Which combination of features applies to ctenophores but NOT to the flatworms described in the lesson?
Ctenophores are radially symmetrical with tissue level of organisation, whereas flatworms are bilaterally symmetrical, triploblastic and acoelomate with organ level of organisation.
Q15. A student observes a translucent, gelatinous marine animal drifting in seawater and notes eight rows of beating ciliated plates along its body. Which conclusion is best supported by the lesson?
Eight external rows of ciliated comb plates that aid locomotion are a defining feature of ctenophores; ctenophores lack the stinging cells that define Cnidaria.