Arthropods are bilaterally symmetrical invertebrates with segmented bodies, jointed appendages, and a rigid external skeleton made primarily of chitin, often strengthened with calcium salts. This exoskeleton must be shed periodically through moulting to allow growth. They are the most diverse and abundant animals on Earth, representing over 80% of all known species and occupying almost … Continue reading "Phylum Arthropoda — Arthropods"

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