Starfish Fossils
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Starfish belong to the phylum Echinodermata, and the class Astroidea.
Starfish, and their close relatives the brittle stars, have been around for a very long time, since the early Ordovician Period about 450 million years ago. They are a member of the Order Echinodermata,which means spiny skin. This group has been Thriving in th earth's oceans since the Cambrian Period. Today it is the largest phylum of marine invertebrates with about 7000 spcies. Other members of this group are seaurchins, sand dollars, crinoids, blastoids, and sea cucumbers. Some major traits all of these animals in common are: a five part radial symetry, and a water based vascular system.
Starfish, and their close relatives the brittle stars, have been around for a very long time, since the early Ordovician Period about 450 million years ago. They are a member of the Order Echinodermata,which means spiny skin. This group has been Thriving in th earth's oceans since the Cambrian Period. Today it is the largest phylum of marine invertebrates with about 7000 spcies. Other members of this group are seaurchins, sand dollars, crinoids, blastoids, and sea cucumbers. Some major traits all of these animals in common are: a five part radial symetry, and a water based vascular system.
Starfish Fact File
- Starfish belong to the Phylum Echinodermata and the class Astroidea.
- Starfish can have as many as 20 arms but most have 5 arms.
- Starfish move using hundreds of small suckers on their under or ventral side.
- Some starfish can grow new arms if one is lost.
- While starfish have the obvious 5 part symetry of echinoderms, they are bilaterally symetrical as larva.
