Sea Star External Anatomy

Echinoderm

Spines

calcerous projections for protection and support

Pedicellariae

pincer-like structures believed to kill small organisms that might settle on body surface

keep epidermis free of parasites and algae

Dermal Branchiae

gas exchange and scretion through simple diffusion

Mouth

external opening to cardiac stomach

Anus

regulates egestion of undigested food from body

Madreporite

porous entrance to water vascular system that serves as both pressure regulator and simple filter

Ambulacral Grooves

radiate from mouth to tip of each arm and house tube feet

Tube Feet

locomotion and prey capture