To which phylum does a spider belong?

To which phylum does a spider belong?

• A. Chordata
• B. Mollusca
• C. Arthropoda
• D. Echinodermata

Answer: (C)

Classification by shared body structure defines arthropods; spiders fall into this group because they have an external exoskeleton, a segmented body, and jointed appendages. These features—especially the jointed limbs and chitinous exoskeleton that spiders molt—set arthropods apart from other major phyla. Chordata includes animals with a notochord and dorsal nerve cord at some stage (like vertebrates); Mollusca comprises creatures such as snails and clams that typically have a muscular foot and mantle rather than jointed legs; Echinodermata includes starfish and sea urchins with radial symmetry and a water vascular system rather than an external skeleton with jointed limbs. Within Arthropoda, spiders are further classified in the subphylum Chelicerata and class Arachnida, which explains their eight legs and distinctive mouthparts.

Classification by shared body structure defines arthropods; spiders fall into this group because they have an external exoskeleton, a segmented body, and jointed appendages. These features—especially the jointed limbs and chitinous exoskeleton that spiders molt—set arthropods apart from other major phyla. Chordata includes animals with a notochord and dorsal nerve cord at some stage (like vertebrates); Mollusca comprises creatures such as snails and clams that typically have a muscular foot and mantle rather than jointed legs; Echinodermata includes starfish and sea urchins with radial symmetry and a water vascular system rather than an external skeleton with jointed limbs. Within Arthropoda, spiders are further classified in the subphylum Chelicerata and class Arachnida, which explains their eight legs and distinctive mouthparts.