The common starfish (Wildlife Trusts) serves as an iconic coastal species across Britain and Ireland, drawing families and explorers to low-tide rockpools in search of its distinctive orange, five-armed form. Despite its familiar appearance, this widespread echinoderm operates without a brain or blood, relying instead on sea water to transport essential oxygen and nutrients throughout its body.
Anatomy and Hydraulics of the Common Starfish
The common starfish lacks centralized nervous processing and circulatory fluids entirely. The species draws in ambient sea water to power its internal vascular network. This circulates oxygen and food while driving thousands of microscopic tube feet located on the underside of its arms.
Did you know? The common starfish possesses two separate stomachs, allowing it to consume prey much larger than its own mouth opening.
Predatory Mechanics and Ancient Feeding Habits
Despite its slow-moving nature, the common starfish acts as a formidable predator, specifically targeting bivalve molluscs such as mussels. The hunt begins when the starfish wraps its arms tightly around a target and utilizes its thousands of tube feet to pry open the bivalve’s paired shells. Once a gap is achieved, the predator forces one of its stomachs through its mouth and into the shell to digest the mussel before retracting the organ back inside.
This specialized, external digestion method dates back more than 450 million years.
Conservation and Habitat Pressures in Intertidal Zones
Common starfish are found on the lowest parts of the shore.
Frequently Asked Questions
Do common starfish have eyes?
Can a starfish regenerate a lost arm?
What do starfish eat besides mussels?
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