Question

Which of the following features is not present in the Phylum-Arthropoda?
A) Chitinous exoskeleton
B) Metameric segmentation
C) Parapodia
D) Jointed appendages

Answer 1

Hint: The term ‘Arthropod’ is made up of two Greek words “arthron” meaning joint and “pous” meaning foot.Hence, the term Arthropod refers to a proposed grouping of Arthropods and the phylum Onychophora.Along with insects, arachnids, myriapods and crustaceans, these invertebrates constitute the phylum Euarthropoda.The term Arthropoda as originally proposed refers to a proposed grouping of Arthropods and the phylum Onychophora.

Complete answer:
> We know that Arthropods are invertebrates meaning they don’t possess or develop a vertebral column.This means they are vulnerable to injuries.Thus, in order to compensate for this, they produce a hard exoskeleton which is made of chitin.This covers and protects their bodies like a suit of armour.Hence, this option is not correct.
> Metameric segmentation is seen when organs and tissues are repeated at intervals along the body of an animal, thus dividing the body into a linear series of similar parts or segments (metameres).This is evident in Arthropods.Hence, this option is wrong.
> Appendages are kind of outgrowths that protrude from an organism's body.These can be modified for feeding, sensing the environment, walking, swimming, defending against predators, and capturing prey.> Whereas jointed appendages allow to have much greater flexibility and range of movement.Thus, this option is also not correct.
> As we have seen that arthropods have a chitinous exoskeleton, metameric segmentation and jointed appendages.But, the Parapodia is mostly used for locomotion and respiration.In the case of Arthropods, both processes are being carried out by their appendages.Consequently, Arthropods don’t have parapodia.
> Thus, the correct answer is Parapodia which is not present in the Phylum-Arthropoda.

Hence the correct answer is option ‘C’.

Note: Arthropods are invertebrates.The invertebrates are bilaterally symmetrical and have metameric segmentation on their bodies.They are characterized by their chitinous exoskeleton paired with jointed appendages on each of their segments.