Educational worksheet for sorting animals into vertebrates and invertebrates.

Final Answer:
Vertebrates: manatee, starfish, dolphin, seahorse, blue whale, hammerhead shark
Invertebrates: jellyfish, squid, snail, octopus

Wait — I made a mistake. Starfish is an invertebrate (it’s an echinoderm, no backbone), and the rest need to be checked.

Let me carefully reclassify each animal using biological facts:

- manatee: mammal → has backbone → vertebrate
- starfish: echinoderm, no backbone → invertebrate
- jellyfish: cnidarian, no backbone → invertebrate
- dolphin: mammal → vertebrate
- seahorse: fish → vertebrate
- snail: mollusk → invertebrate
- blue whale: mammal → vertebrate
- squid: mollusk → invertebrate
- hammerhead shark: fish → vertebrate
- octopus: mollusk → invertebrate

So correct grouping:
- Vertebrates: manatee, dolphin, seahorse, blue whale, hammerhead shark
- Invertebrates: starfish, jellyfish, snail, squid, octopus

Now I’ll double-check with a reliable source.