We are still classifying the Sea-Monkey on the Phylum level, the 4th level down on the left. Sea-Monkeys are in the major classification of arthropods. The Arthropod major phylum is typically subdivided into five subphyla, of which one is extinct called trilobites. So, that leaves four as shown in the picture. The four phyla in the picture are 2) Chelicerates that include scorpions, 3) Myriapods that include millipedes and centipedes, 4) Crustaceans that include crabs, and 5) Hexapods that include. Look at the picture on the right. Which animal is the most similar to the Sea-Monkey? If you picked Crustacean, then you are correct. Sea-Monkeys are Arthropod-Crustacean.