Pay special attention to Echinoderms (starfish) and Chordates.
Does it have two layers (diploblastic) or three (triploblastic)?
Before diving into specific animals, you need to understand the "rules" of life. Focus on:
Start with Porifera (sponges) and move through Cnidarians, Platyhelminthes (flatworms), Mollusks, Annelids, and the massive group of Arthropods (insects/spiders).
How they manage waste (ammonia vs. urea vs. uric acid).
Is it radial (like a jellyfish), bilateral (like us), or asymmetrical (like a sponge)?
Learn the hierarchy (Kingdom, Phylum, Class, etc.). Modern zoology relies heavily on Cladistics —grouping animals by shared ancestry rather than just looking alike. 2. The Architectural Plan: Body Design Animals are often categorized by their "build":