The name "starfish" is actually a misnomer, causing many scientists to want to have the name of the species changed. A starfish is not a fish at all, but rather an animal closely related to both the sea urchin and sand dollar. Starfish, or sea stars, live in salt water and consume food through their arms.
The first step to understand a starfish's movement is understanding its skeletal system. While the starfish's internal organs are protected by the skeleton, it does not have joints like other animals. Instead, it uses its water vascular system to inch along the ocean floor, searching for food and other prey.
When a starfish moves, it moves simply, inching forward. A starfish does not have blood inside of it, but rather relies on water to pump the nutrients from its food through its body. It is this system that aids him in his movement, allowing his muscles to contract and extend, using the tubes underneath his arms to grab a hold of objects around him.
Moving Around Underwater
Starfish do not have eyes, but they are able to see. Each arm has an eyespot, which helps the starfish locate both shapes and light. The starfish can use this to detect predators and to move toward prey. This also helps the starfish know which way he is moving so that he does not run into danger.
Why Starfish Move
Starfish move relatively slowly, which makes them an easy target for prey. However, they do move when hunger strikes them, and they can use their arms to pry open clams and oysters. Their stomachs will emerge from their bodies and then eat its food before retracting back. Although starfish can be easy prey for other animals, they can create a new starfish if at least one of its arms was left. As most of its vital organs are in its arms, this makes it easy for it to then grow into a new animal.
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