Question

Which is not the characteristic feature of arthropods
(a) Jointed appendages
(b) Moulting
(c) Unsegmented body
(d) Auriculated skeleton

Answer 1

Hint: The body of arthropods is divided into head, neck, and thorax. The word arthros means joint and podium mean foot. The body is covered by a chitinous skeleton for protection.

Complete answer:
The arthropods are divided into head, thorax, and abdomen. The body of arthropods is covered by protection called a chitinous exoskeleton that prevents water loss. This chitinous exoskeleton is shed off periodically by a process called molting or ecdysis. They have jointed appendages.
So, the correct answer is ‘Unsegmented body’.

Additional information:
- Arthropoda is the largest phylum in the Animalia kingdom.
- In the word arthropods, arthos mean joints and podium, mean foot
- Two- thirds of the named species in the world are called arthropods i.e, 80% of animal species.
- They are triploblastic, bilaterally symmetrical, metamerically segmented, schizocoelomate animals.
- Chitinous exoskeleton is covered on the body of arthropods which prevents the water loss.
- This protection layer periodically sheds off by a process called molting or ecdysis.
- Growth of the body in arthropods is due to the molting process.
- Arthropods have jointed appendages
- Muscles are striated and they help in rapid locomotion.
- The body cavity of these organisms is filled with hemolymph which is formed by the fusion of embryonic blastocoel and some coelomic spaces, so it is called hemocoel.
- Gills, book gills, book lungs, or trachea are the respiratory organs in arthropods
- They have an open type of circulatory system and the heart is dorsal in position.
- Haemocyanin is the respiratory pigment that is present in the hemolymph.

Note:
- In the process of evolution, striated muscles are first seen in arthropods.
- The respiratory pigment, hemocyanin contains copper.
- Examples of arthropods: Periplaneta, Palaemon, cancer, aranea, etc.