Phylum Echinodermata: The Spiny-Bodied Marine Animals
Echinoderms are among the most distinctive groups in the animal kingdom. Their name means “spiny-bodied,” and it comes from the calcareous ossicles that form their internal skeleton. This quiz tests the defining features of the phylum: an exclusively marine habitat, radial symmetry in adults with bilateral symmetry in larvae, a triploblastic and coelomate body plan, a complete digestive tract, and the remarkable water vascular system that handles locomotion, food capture and respiration.
What you should know before starting
- Echinoderms are all marine and show organ-system level organisation.
- Adults are radially symmetrical; larvae are bilaterally symmetrical.
- The mouth lies on the ventral side and the anus on the dorsal side.
- An excretory system is absent.
- Fertilisation is usually external and development is indirect with a free-swimming larva.
Work through the fifteen questions carefully — each explanation reinforces the exact wording examiners look for.
Q1. The name Echinodermata literally means:
Echinodermata is derived from Greek roots meaning "spiny bodied," referring to the spines produced by the calcareous ossicles.
Q2. The endoskeleton of echinoderms is made up of:
The echinoderm endoskeleton consists of calcareous ossicles, small plates and spicules of calcium carbonate lying beneath the skin.
Q3. Regarding habitat, echinoderms are:
Every member of the phylum is marine; no freshwater or terrestrial echinoderms exist.
Q4. The symmetry of an adult echinoderm is:
Adult echinoderms are radially symmetrical, which is unusual among the triploblastic animals.
Q5. The symmetry of an echinoderm larva is:
Echinoderm larvae are bilaterally symmetrical, and this bilateral symmetry gives way to radial symmetry in the adult.
Q6. In terms of body plan, echinoderms are:
Echinoderms are triploblastic and coelomate animals with organ-system level of organisation.
Q7. The level of organisation seen in echinoderms is:
Echinoderms show organ-system level of organisation, placing them alongside molluscs and chordates.
Q8. In echinoderms, the mouth and anus are positioned respectively on the:
The digestive system is complete, with the mouth on the lower (ventral) side and the anus on the upper (dorsal) side.
Q9. The most distinctive feature of echinoderms is the:
The water vascular system is the most distinctive feature of the phylum and serves locomotion, food capture and transport, and respiration.
Q10. The water vascular system of echinoderms helps in all of the following EXCEPT:
The water vascular system aids locomotion, food capture and transport, and respiration. An excretory system is absent in echinoderms.
Q11. Which system is absent in echinoderms?
An excretory system is absent in echinoderms, a notable feature of the phylum.
Q12. The digestive system of echinoderms is:
The digestive system is complete, with a ventral mouth and a dorsal anus.
Q13. Regarding sexes and fertilisation in echinoderms:
Sexes are separate, reproduction is sexual, and fertilisation is usually external.
Q14. Development in echinoderms is:
Development is indirect, passing through a free-swimming larval stage.
Q15. Which of the following is NOT an example of Phylum Echinodermata?
Balanoglossus is a hemichordate. The echinoderm examples are Asterias, Echinus, Antedon, Cucumaria and Ophiura.