Question

Give the special feature of phylum Echinodermata. What are the similarities between phylum Echinodermata and phylum Chordata?

Answer 1

Hint: Phylum Echinodermata consist of only marine organisms like sea cucumbers, sand dollars, sea stars etc. No terrestrial or freshwater organisms have been found in Echinoderms till now.

Complete Solution:
Special features of phylum Echinodermata are as follows-
1. They are exclusively marine organisms.
2. Their body appearance is star like.
3. They are triploblastic, i.e., they possess three germ layers.
4. They exhibit Organ level of organization.
5. Their skeleton is made of calcium carbonate.
6. They are spiny skinned organisms.
7. Circulatory systems in these organisms are open type.
8. Respiration occurs through gills or cloacal respiratory tree.
9. Nervous system is simple and radial in them.
10. Excretory system is absent in those organisms.
11. Unsegmented body with mouth on the ventral side and anus on the dorsal side.
12. Tube feet help them in locomotion.
13. Asexual reproduction is through regeneration and sexual reproduction is through gametic fusion. External fertilization occurs.
14. Power of regeneration is very high in those organisms.
15. Development is indirect.
Some of the similarities between phylum Echinodermata and phylum Chordata are-
1. They both exhibit radial symmetry.
2. They both are a closely related group of organisms.
3. They both have true body cavities or coelom.
4. Sexual reproduction is the main form of reproduction in both organisms.
5. They both exhibit bilateral symmetry.
6. Presence of blastospores is common in both of them. In a developing organism, the first formed cavity is known as a blastopore. Later on, this blastopore converts to anus or tail.
7. Indeterminate cleavage is common in both of them. Indeterminate means that if during development cells break apart, they can still develop into two individuals.

Note:
Phylum Echinodermata consist of some special features like exclusively marine, star like appearance, triploblastic origin, open circulatory system, external fertilization, respiration through gills, etc.
There are some common characteristics in echinoderms and chordates like radial symmetry, presence of coelom, sexual reproduction is common in both of them, bilateral symmetry, presence of blastopore and indeterminate cleavage.