Question

Characters of a phylum are given below. Read those carefully and answer the questions
a. Spines of calcium carbonate are present on the body.
b. These animals are exclusively marine.
c. They perform the locomotion with the help of tube feet.
d. Their skeleton is made up of calcareous plates or spicules.
   i. Animals of which phylum show the above characters?
   ii. Give an example from that phylum.
   iii. These animals can be classified with the help of which criteria of a new system of animal classification?

Answer 1

Hint: Spines on the body is a key characteristic of Phylum Echinodermata. Here, ‘Echino’ means spines and ‘dermata’ refers to skin or body surface. So in that case animals belonging to phylum Echinodermata show the characters which are mentioned above.

Complete answer:
The characteristic that is mentioned in the question is of Phylum Echinodermata. Members of Phylum Echinodermata are also known as spiny skinned organisms. Starfish, Brittle star, Sea urchins, Sea cucumbers, Sea lilies, etc. are a few examples of echinoderms.
- The key distinguishing characteristics that are used to identify the echinoderms according to the new system of animal classification are as follows:
- Pentamerous radial symmetry.
- Presence of a unique water vascular system.
- Presence of tube feet for locomotion.

Let's see other important characteristics of Echinoderms:
- They are exclusively marine.
- They are triploblastic, and eucoelomate.
- It exhibits the organ system grade of body organization.
- Their body is without a head and is unsegmented.
- They show star-like, elongated, or spherical body shapes.
- The whole body surface is covered with calcareous spines.
- Endoskeleton is also made up of calcareous spicules.
- Their nervous system comprises a nerve ring and radial nerve cords.
- Respiration occurs using tube feet and gills.
- Echinoderms show external fertilization.
- Echinoderms have great power of regeneration.

Note: Many phyla include marine animals. Then, other than echinoderm, calcareous spicules are present in sponges (Phylum Porifera) also. But remember, tube feet for locomotion along with calcareous spines over the body surface are distinguishing features of Echinoderms.