Read the text. Invertebrates make up the majority of Earth's living things, but there are many different
groups, or phyla, of invertebrates. Jellyfish and sea anemone, for example, are both part
of the phylum Cnidaria. Cnidaria comes from a Greek word that means "nettle," a
stinging type of plant. Cnidarians are known for the tentacles that surround their mouths,
which they use to sting and capture prey. All species that belong in the Cnidaria phyla
live exclusively in the ocean.
Another phylum of invertebrates found only in oceans is the Echinodermata, a term that
comes from Greek words meaning "spiny" and "skin." Echinoderms, members of this
phylum, have stiff bodies and often have stiff, sharp spines covering their skins. Unlike a
cnidarian's wavy tentacles, these spines are used for protection, not to capture prey.