What are the suction cup things on bottom of starfishes legs?

Here's why they're important:

* Movement: Tube feet are the primary means of locomotion for starfish. They work by hydraulic pressure, filling with water and extending outwards. The suction cup at the end of each tube foot then adheres to the surface, allowing the starfish to move slowly but powerfully.

* Feeding: Tube feet help starfish capture and manipulate their food. They can use the suction to pry open shells of bivalves like clams and mussels.

* Sensory: Tube feet are also sensitive to touch and chemicals, helping the starfish find food and navigate.

So, while they may look like simple suction cups, tube feet are incredibly complex and essential to the starfish's survival!