The video introduces invertebrates, animals without a backbone, which make up 95% of the animal kingdom. It explains the classification of invertebrates into groups such as insects, arachnids, and mollusks. Insects like the Titan beetle have an exoskeleton for support. Arachnids include spiders and scorpions, while mollusks include slugs and squid. The video highlights the diversity of invertebrates, making them the most varied group of organisms on Earth.

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