A shallow groove along the digital midline of each arm is called an ambulacral groove in the phylum Echinodermata. These grooves arise from each side of the five corners of their mouth. For example, sea star (Asterias vulgaris).
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A shallow groove along the digital midline of each arm is called an ambulacral groove in the phylum Echinodermata. These grooves arise from each side of the five corners of their mouth. For example, sea star (Asterias vulgaris).