The Eagle Ray Family – Myliobatidae
The Cownose Ray, Rhinoptera bonasus, a representative of the Eagle Ray or Myliobatidae Family.
The Eagle Ray or Myliobatidae Family is a relatively small family of moderate to large size fish with strongly depressed bodies flattened into diamond-shaped discs. Some systematists divide the family into three sub-families, Mobulidae, while others treat them as three separate families. In this website, I have elected to treat them as three separate families. The Myliobatidae Family includes twenty global species that have been placed in four genera. Of these, one species is found in the Atlantic, three in the Pacific, and one in both oceans. They are known as águilas marinas in Mexico.
The Eagle Rays are gray to dark brown on their dorsal side and off-white on their ventral side; some have dark margins on their discs. Their head, trunk, and pectoral fins form a disc that is wider than it is long and can reach up to 2.5 meters (8 feet 2 inches) in width. Their head is elevated from the disc and their eyes and spiracles are on the sides. Their mouth is straight to slightly arched with teeth that are flattened plates arranged like pavement stones in one to seven series. They have a whip-like tail that is much longer than their disc. They have a small dorsal fin at the base of their tail and most have a poisonous serrated spine immediately behind their dorsal fin. They do not have a caudal fin and their pectoral fins are either very small or absent. Many have skin denticles on their dorsal surface.
The Eagle Rays are found in tropical and temperate global waters over the continental and insular shelves. They are active swimmers capable of traveling long distances by flapping their pectoral fins. They can be found at all depths of the water column and normally travel in groups near the bottom. They consume benthic crustaceans and hard shell mollusks. Reproduction is ovoviviparous without a placenta and via lipid histotrophy whereby developing embryos are supplied with protein and lipid-enriched uterine milk by their mothers. Litters of two to six pups are born live as miniature adults. They are generally too rare to be of interest to most. They date to the Upper Cretaceous Period, one hundred million years ago.
There are eight members of the Eagle Ray or Myliobatidae Family, one from the Atlantic and six from the Pacific, currently presented in this website:
Bat Ray, Myliobatis californica
Cownose Ray, Rhinoptera bonasus
Golden Cownose Ray, Rhinoptera steindachneri
Longnose Eagle Ray, Myliobatis longirostris
Pygmy Devil Ray, Mobula munkiana
Rough Eagle Ray, Pteromylaeus asperimus
Smoothtail Mobula, Mobula thurstoni
Spotted Eagle Ray, Aetobatus narinari