Asterozoa
echinoderm subphylum
Quick Summary
Asterozoa is a subphylum of echinoderms that includes starfishes (Asteroidea) and brittle stars (Ophiuroidea). These marine invertebrates are characterized by a radial symmetry, typically with five arms that grow in a single plane from a central body. They possess a mouth at the center and have tube feet, which are part of their water-vascular system. Asterozoa have existed from the Lower Ordovician period, approximately 500 million years ago, to the present day.12
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