Which respiratory structure is typical for aquatic crustaceans?

• A. Gills
• B. Lungs
• C. Tracheae
• D. Skin

Answer: (A)

Aquatic crustaceans typically rely on gills to extract oxygen from water. Gills are specialized, highly branched membranes with a large surface area and thin diffusion barriers that maximize gas exchange. Water passes over these moist surfaces, driven by the animal’s movement or by specialized pumping, so oxygen in the water diffuses into the blood while carbon dioxide diffuses out. This setup is ideal for living in an aquatic environment where oxygen is dissolved in water but not freely available as air. In contrast, lungs require air, tracheae are insect-like air tubes, and skin respiration is generally insufficient for most crustaceans, making gills the standard respiratory structure.