What is the Difference Between Crustaceans and Molluscs (Mollusks)?

Crustaceans and mollusks are both types of shellfish, but they have distinct differences in their structure and biology. Here are the main differences between the two:

Crustaceans:

• Aquatic animals with jointed legs, a hard shell, and no backbone.
• Examples include crab, crayfish, lobster, prawns, and shrimp.
• Their body is segmented into the abdomen and cephalothorax.
• They have a chitinous exoskeleton.
• They have biramous appendages.
• Most crustaceans are free-living aquatic organisms, while some are terrestrial.

Mollusks (Molluscs):

• Soft-bodied invertebrates covered in a calcareous shell.
• Examples include clams, mussels, oysters, scallops, octopus, snail, and squid.
• They have soft, unsegmented bodies.
• They have a muscular foot and a visceral hump.
• They do not have biramous appendages.
• They can live in both land and sea environments.

In summary, crustaceans have a hard shell and jointed legs, while mollusks have a soft body and a calcareous shell. Crustaceans are segmented, while mollusks are unsegmented. Crustaceans have biramous appendages, while mollusks do not.

Comparative Table: Crustaceans vs Molluscs (Mollusks)

Crustaceans and mollusks are two distinct groups of invertebrate animals that belong to the phylum Arthropoda and the phylum Mollusca, respectively. Here is a table summarizing their main differences:

Crustaceans are characterized by their segmented bodies, chitinous exoskeletons, and biramous appendages. On the other hand, mollusks have soft, unsegmented bodies, calcareous shells, and no biramous appendages. They also possess a muscular foot and a visceral hump, which are absent in crustaceans.