Question

Differentiate between Arthropoda and Mollusca.

Answer 1

Hint: Arthropods and molluscs are both invertebrates. Arthropods are organisms having exoskeleton and segmented bodies with paired appendages. On the other hand, the molluscs have shells surrounding their soft bodies.

Complete answer: Arthropods and molluscs show great diversity in invertebrates. These phyla have the highest diversity as compared to any phyla of the animal kingdom. Both arthropods and molluscs show bilateral symmetry, which means that their bodies are divided into two equal halves.

Differences between arthropods and molluscs:

Arthropoda	Mollusca
Arthropods are animals having a segmented body with paired appendages or legs.	Molluscs are animals having soft bodies usually covered in mucus.
The arthropods have exoskeleton covers on their body. This is generally made of chitin.	Molluscs have their soft bodies covered and protected by hard shells.
The Arthropoda is the largest phylum of the kingdom Animalia.	The Mollusca is the second largest or diverse phylum in the animal kingdom.
Spiders, scorpions, shrimps, mites, crabs, lobsters, insects, etc. are examples of arthropods.	Snails, clams, squids, etc. are examples of molluscs.
Arthropods have wings to fly with jointed legs usually to their abdominal segments.	Molluscs have a muscular foot that helps in locomotion.
In arthropods, the exoskeleton is made up of chitin.	The shells in the molluscs are made of calcareous substances secreted by mantles.
Most of the arthropods have closed circulatory systems.	Molluscs have open circulatory systems.

Note: The presence of exoskeleton in arthropods gives them their characteristic property of moulting. Moulting refers to the shedding of the previous exoskeleton cover and the appearance of a new exoskeleton. The exoskeleton is hard and thus restricts the growth of arthropods. For this reason, the arthropods moult their exoskeleton regularly.