Question

How do Annelid animals differ from Arthropods? Explain.

Answer 1

Annelids:

1. Phylum Annelida is a cultivated species belonging to the kingdom Animalia.
2. Annelids are found in both aquatic and terrestrial environments.
3. These are bilaterally symmetrical invertebrates.
4. They have a segmented body.a
5. It distinguishes them from any other organism.
6. The Annelids are coelomate, and they are triploblastic.
7. They show organ system level organization.
8. They respire through their body surface.
9. Their excretory organs are nephridia.
10. Their body contains hemoglobin, which gives them a red color.
11. Regeneration is a common characteristic of the Annelids.
12. Setae help them in movement.
13. Most Annelids are hermaphrodites, i.e., male and female organs are present in the same body.
14. They reproduce both sexually and asexually.

Arthropods:

1. Arthropoda is the largest phylum with about nine lakh species.
2. They may be aquatic, terrestrial, or even parasitic.
3. They have jointed appendages, and their exoskeleton is made of chitin.
4. This species contains several large classes and includes the class Insecta.
5. It represents a significant portion of the animal species in the world.
6. They possess the ability to survive in every habitat.
7. They possess an organ system level of organization.
8. The body has a head, thorax, and abdomen.
9. Their body has jointed appendages that help in locomotion.
10. The coelomic cavity is filled with blood.
11. They have an open circulatory system.
12. The head bears a pair of compound eyes.
13. The exoskeleton is made of chitin.
14. The terrestrial Arthropods excrete through Malpighian tubules.
15. The aquatic ones excrete through green glands or coaxal glands.
16. They are unisexual, and fertilization is either external or internal.
17. They respire through the trachea.

The difference between annelids and Arthropods are tabulated below:

Annelids	Arthropods
1. Metameric segmentation is seen, head to tail of the body is segmented.	1. Incomplete metameric segmentation, segmentation is not found in the body.
2. Annelids have a closed circulatory system.	2. Arthropods have an open circulatory system.
3. The body is divided into several identical segments.	3. The body is divided into only few specialized segments.
4. Annelids don't have appendages.	4. Arthropods have jointed appendages.
5. They are referred to as segmented worms.	5. They are termed animals with jointed legs.
6. The coelom is the true body cavity they possess.	6. Presence of body cavity containing blood known as ‘hemocoel'.
7. Breathing takes place through the skin.	7. Breathing takes place through the trachea, gill, book lungs, etc.
8. Most annelids are hermaphrodites.	8. Arthropods have separate sexes.
9. Example – Nereis, Earthworm	9. Example – Housefly, crab