They all have a head, thorax. and abdomen. The thorax has three pairs of legs and often one pair of wings. Most flowering plants are pollinated by insects. Fleas are parasites on warmed-blooded vertebrates. Usually their body is covered with scales and coated with slime.
Jawless fish have a long tube like body and a sucker mouth, no jaw, and no fins.
Cartilage fish have a skeleton of cartilage and a jaw. Cartilage fish such as sharks have fins. The eggs are immediately fertilized by the male. Reptiles, amphibians, and fish are cold-blooded vertebrates. They do not produce their own food as plants do.