Use the following Classes of Arthropoda to answer the question below I. Crustacea II. Insecta III. Arachinda…

Analyze the question: It asks which of the four arthropod classes has members that live mainly in water (an aquatic habitat).

Explain the concept: Arthropoda is divided into classes based on body structure and habitat:

• Crustacea (crabs, prawns, shrimps, lobsters, crayfish, water fleas): mostly aquatic. They breathe with gills, and they have two pairs of antennae.
• Insecta (cockroach, grasshopper, housefly, butterfly): mainly terrestrial, with some aerial. They have 3 pairs of legs and breathe with tracheae.
• Arachnida (spiders, scorpions, ticks, mites): mainly terrestrial. They have 4 pairs of legs and no antennae.
• Chilopoda (centipedes): terrestrial. They live under stones and logs and have one pair of legs per body segment.

Step-by-step solution:

1. Check each class for its typical habitat.
2. Insecta, Arachnida and Chilopoda are all mainly land dwellers.
3. Only Crustacea has members that live mainly in water (fresh and marine), such as crabs, prawns and Daphnia.

Answer: Crustacea (I), which is option A.

Tip: Think "Crustacea = Crab, Crayfish, and water." Crabs and prawns are the seafood you know, so Crustacea is the aquatic class. Remember that "mainly" matters here: a few insects, like water beetles, live in water, but most insects are terrestrial.