Starfish, or sea stars, are marine invertebrates with a central disc and multiple arms—usually five, but some species can have up to 40. Their bodies are covered in skin that can be smooth or spiny, with vibrant colors and patterns varying among species. Starfish can range in size from a few centimeters to over a meter in diameter.

These creatures move using tube feet located on the underside of their arms, part of a unique water vascular system. They are known for their diverse diet, which includes mollusks, small fish, and detritus. Starfish have an intriguing feeding method where they extend their stomachs outside their bodies to digest food.

Starfish inhabit various marine environments, from shallow tide pools and coral reefs to deep-sea floors, and can adapt to different water conditions. They reproduce both sexually and asexually, with many species capable of regenerating lost arms, and in some cases, an arm can grow into a new individual.