Why are star fish called if they not fish?

* They lack key fish features: Fish have gills for breathing underwater, scales, fins for swimming, and a streamlined body shape. Starfish have none of these.

* They are echinoderms: Starfish belong to the phylum Echinodermata, which also includes sea urchins, sea cucumbers, and brittle stars. Echinoderms have radial symmetry (their bodies are arranged around a central point), a hard, spiny outer skeleton, and a water vascular system for movement.

* They don't have a backbone: Fish are vertebrates, meaning they have a backbone. Starfish are invertebrates, meaning they lack a backbone.

So, the name "starfish" is a bit of a misnomer. They are actually more closely related to sea urchins and sea cucumbers than to fish. However, the name has stuck because of their star-like appearance and marine habitat.