Manta rays are large rays belonging to the genus Mobula. The larger species, M. birostris, reaches 7 m (23 ft) in width, while the smaller, M. alfredi, reaches 5.5 m (18 ft). Both have triangular pectoral fins, horn-shaped cephalic fins and large, forward-facing mouths. They are classified among the Myliobatiformes and are placed in the family Myliobatidae. They have the largest brain-to-body ratio of all fish, and can pass the mirror test.