Question

The locomotory organs of Echinodermata are
(a) Tube feet
(b) Muscular feet
(c) jointed legs
(d) parapodia

Answer 1

Hint: Locomotory organs in all classes of Echinoderms have suckers except in organisms belonging to Crinoidea. Locomotion is due to the presence of a water vascular system.

Complete answer:
Echinoderms are marine organisms that are radially symmetrical. The body wall is thick and they contain an endoskeleton of mesodermal origin. The most distinctive feature of echinoderms is the presence of a water vascular system that helps in locomotion, food collection, and prey capture. They contain locomotory structures called tube feet.

Additional Information:
- Echinoderms are deuterostomes with radial bodies. They are non-chordate enterocoelomates.
- All the organisms in Echinodermata are marine. They are radially symmetrical but their larvae are bilaterally symmetrical.
- Body wall is thick and the body surface is spiny which possesses a mesodermal skeleton made up of calcareous ossicles that support the spine. Because of this feature, they are named as Echinodermata
- In some organisms spines are modified into pedicellariae
- Echinodermata is subdivided into 2 subphyla namely PelMetazoa and Eleutheroza
- Pelmetazoa has one class called Crinoidea that includes the most primitive and oldest forms. Tube feet do not bear suckers examples: ptilocrinus, bathycrinus and neomata
- Eleutherozoa is divided into four classes namely Asteroidea, Ophiuroidea, Echinoidea, Holothuroidea.
- Asteroidea contains sea stars or starfishes. Tube bears suckers in these organisms. Pedicellariae are two jawed and are useful for food capture. Examples; Asterias, Astropecten
- Organisms in Ophiuroidea move by the serpentine lashing of arms. Examples: brittle stars, serpent stars
- In Echinoidea, arms are absent and tube feet bear suckers. Examples: sea urchins sand dollars
- In Holothuroidea, arms, spines, and pedicellariae are absent. Examples: Holothuria
So, the correct answer is ‘Tube feet’

Note: An open type of circulatory system is seen in Echinoderms. They respire through papulae or dermal branchiae. They are diecious but they do not exhibit sexual dimorphism. They show sexual reproduction and development is indirect with free-swimming symmetrical larvae.