▶️ Answer/Explanation
Fish are ectothermic, meaning they do not maintain a constant body temperature. Their eggs are typically laid in water and are covered in a jelly-like substance for protection and hydration. Unlike mammals, fish do not have external ears (pinnae), though they can detect vibrations. Finally, most fish possess scales that cover their skin for protection and streamlining. Row (D) correctly identifies all these biological traits.
✅ Answer: (D)
✅ Answer: (D)
▶️ Answer/Explanation
Arthropods are invertebrates characterized by having an exoskeleton, a segmented body, and paired jointed appendages. The phylum Arthropoda is primarily divided into four main groups: insects, arachnids, crustaceans, and myriapods.
Option (B) is correct because all three groups listed—arachnids (spiders, scorpions), crustaceans (crabs, lobsters), and myriapods (centipedes, millipedes)—are true arthropods. The other options are incorrect because they include vertebrates: amphibians (A), fish (C), and reptiles (D), which possess internal backbones and do not belong to the arthropod phylum.
✅ Answer: (B)
▶️ Answer/Explanation
To identify the crustacean, we look at the anatomical features of these arthropods. Animal A is an insect (bee/fly) with $3$ pairs of legs and wings. Animal B is an arachnid (spider) characterized by $4$ pairs of legs. Animal C is a myriapod (centipede) with many body segments and pairs of legs. Animal D is a crab, which is a classic example of a crustacean. Crustaceans typically have two pairs of antennae and a hard exoskeleton, often with $5$ or more pairs of legs including pincers.
✅ Answer: (D)
✅ Answer: (D)