Final answer:
Jellyfish, earthworms, grasshoppers, and humans are all classified as invertebrates, which are animals without a vertebral column. They belong to different phyla: Cnidaria (jellyfish), Annelida (earthworms), and Arthropoda (grasshoppers).
Step-by-step explanation:
Jellyfish, earthworms, grasshoppers, and humans are all classified in the same broad group known as invertebrates. This classification includes animals without a vertebral column or spine. While these organisms drastically differ in appearance and habitat, they share the characteristic of lacking a backbone. For example, jellyfish, belonging to the phylum Cnidaria, are marine invertebrates known for their stinging cells. Earthworms, in the phylum Annelida, are segmented worms crucial for soil aeration and can be found in terrestrial environments. Grasshoppers fall under the incredibly diverse phylum Arthropoda, which includes all insects, spiders, and crustaceans with jointed appendages and an exoskeleton. Lastly, while humans have a vertebral column, they are still part of the overarching category of animals distinguished by having eukaryotic cells without cell walls and being multicellular.