Question

What distinguishes an insect from a crustacean? A. Number of eye B. Arrangement of nerve chord C. Number of appendages D. Presence of exoskeleton

Answer 1

Hint: Crustacean belongs to a large and diverse group of arthropods. Most of the crustaceans are free-living and many of them are terrestrial and are parasitic in nature. The body of the crustacean is divided into segments. Insects have a chitinous exoskeleton and have a three-part body. They are the most diverse group on earth.

Complete answer:Crustacean is chiefly aquatic arthropod of the class crustacea. They have the body covered with a hard shell or crust. Examples are Crabs, lobsters, crayfish, shrimps, etc. Insects such as ants, flies, wasps, etc have tri-segmented bodies such as head, neck, abdomen. But on the other hand crustaceans such as crabs, shrimps, lobsters, and crayfish have only two body segments which are head and thorax. These two segments fuse together and form the cephalothorax and abdomen. Insects have three pairs of legs and attached to their thoracic region whereas crustaceans have more than three pairs of legs [usually five pairs]. So, variations are present between many species. The distinguishing feature between an insect and crustacean is the number of appendages’.
Types-
-Crabs are built for both defense and attack.
-Lobsters are covered in heavy outer shells called exoskeletons.
-Prawns and shrimps have thin bodies.
-Woodlice live on land, unlike many crustaceans.
-Smaller aquatic crustaceans eat microscopic organisms, like algae while their larger counterparts enjoy diets of snails and the larvae and eggs of other marine life.
-Large lobsters and crabs survive on fish and other crustaceans.
So the correct answer is C ‘number of appendages’.

Note: The crustaceans are some of the most important marine life to humans –crabs, lobsters, and shrimp are widely fished and consumed around the world these are also very important to other marine life; they serve as prey for marine animals such as whales and fish.