Jan 23 2009
Movement without Eyes Nor Ears
How does a starfish navigate? Inquiring minds want to know. By sense of touch? The above was photographed in the Bahamas in roughly 15 feet of water.
This blurb from Wikipedia is somewhat educational:
Sea stars do not rely on a jointed, movable skeleton for support and locomotion (although they are protected by their skeleton), but instead possess a hydraulic water vascular system that aids in locomotion. The water vascular system has many projections called tube feet on the ventral face of the sea star’s arms which function in locomotion and aid with feeding. Sea stars usually hunt for shelled animals such as oysters and clams. They have two stomachs. One stomach is used for digestion, and the other stomach can be extended outward to engulf and digest prey. This feature allows the sea star to hunt prey that is much larger than its mouth would otherwise allow.
But how do they navigate?
Aha!
On the end of each arm or ray there is a microscopic eye which allows the sea star to see, although it only allows it to see light and dark, which is useful to see movement.
Thanks Wikipedia! I guess I should amend my title to “Without Obvious Eyes.”
