List of animal phyla
At least 21 phyla are exclusively aquatic, with several others in quasi-aquatic habitats on land. None are entirely terrestrial. This is testimony to the importance of water for life, and to the sea in particular. It is fairly certain that all phyla originated in the sea or, at any rate, in water. Most made their first showing in the Cambrian, or in the Ediacaran. Most of the soft-bodied phyla have left few fossils.