Feeding: They eat almost anything that moves slower than they do – which is a lot of sea creatures. Sea stars are successful scavengers and predators. Some attack mollusks, like mussels and oysters, which don't move, and some feed on dead fish or other carrion.
Internal Transport: Water enters the water vascular system through a sieve plate and passes into radial canals within each arm. Official pathways are aboral madreporite---stone canal--ring canal--5 radial canals--numerous am pull bearing tube feet.
Response:A starfish has a primitive nervous system that interconnects sensory receptors that detect injurious stimuli with muscle cells that cause movements enabling the starfish to move away from the nociceptive stimuli. Starfish have no brain so there is no pain.
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Respiration:Starfish breathe through their feet. Their feet are made of thin tissue that gases can easily move through. Starfish’s tubed feet and tiny bumps all over their bodies transport the oxygen from the seawater to their tissues. They move carbon dioxide from their tissues to the seawater.
Excretion:The process of execretion, like many other of the Echinoderm's processes use it's water vascular system. This unique system includes a series of internal canals connected to external body parts called tube feet, this allows Echinoderm's to use thier water vascular system for excretion and other processes (i.e. respiration, movement etc.)
Movement:By moving water from the vascular system into the tiny feet, the sea star can make a foot move by expanding it. This is how sea stars move around. Muscles within the feet are used to retract them. Each ray of a sea star has a light sensitive organ called an eyespot. |
Reproduction:Starfish commonly reproduce by free-spawning: releasing their gametes into the water where they hopefully are fertilized by gametes from the opposite sex. To increase their chances of fertilization, starfish probably gather in groups when they are ready to spawn, use environmental signals to coordinate timing,and may use chemical signals to indicate their readiness to each other.