Cownose Ray - Rhinoptera bonasus
Diagnostic characters: Batoids of moderate to large size, disc width up to 2 m; disc rhomboid or lozenge- shaped, distinctly broader than long. Anterior part of head distinctly elevated from disc; anterior section of pectoral fin separated from remainder of fin and forming fleshy subrostral lobe, lobe extends slightly in front of head and is deeply incised medially. Eyes and spiracles on sides of head. Mouth nearly transverse; fleshy papillae absent on floor of mouth; teeth consist of flattened plates arranged like pavement stones in 6 to 9 series, forming dental plate in each jaw; those of medial column largest. Anterior lobe of nostrils posteriorly expanded into broad nasal curtain, with posterior margin fringed. Pectoral fins falciform, originating on dorsal side of head posterior to orbits. One small dorsal fin located between medial margins of pelvic fins; caudal fin absent; tail distinct from trunk, very slender, and circular in cross-section; longer than disc width; armed with 1 (rarely more) long, serrated, poisonous spine(s), located immediately posterior to dorsal fin. Skin entirely smooth on dorsal and ventral sides, or roughened with denticles on dorsal surface and on midline of body. Colour: dorsal surface greenish brown, brown, bronze, or grey; ventral surface whitish, border of disc often dark like dorsal surface; tail dark.
Size: Maximum size 91 cm disc width; females mature at 78 cm disc width; neonates about 37 cm disc width at birth.
Habitat, biology, and fisheries: Benthic to epipelagic along the continental and insular shelves. Litters from 1 to 2 young (Jones et al, 2015; Smith and Merriner, 1986; McDowell and Fisher, 2013; Fisher, 2010). Feeds primarily on hard-shelled molluscs and crustaceans. Occasionally they are observed at the surface and leaping out of the water but generally
swim near the bottom in small groups.Dorsal surface uniform brown; ventral surface white to yellowish. Tooth plates with relatively long teeth compared to Rhinoptera brasiliensis. Cownose rays are not directly targeted by fisheries but they are frequently caught in tropical waters and are processed fresh or salted for human consumption. Several Chesapeake Bay restaurants are now serving Cownose ray on menu with the slogan "Eat a ray, save the bay".
Distribution: Recorded from southern New England to northern Argentina, including the Gulf of Mexico, and Cuba.
Jones, C. M. and Driggers III, W. B. 2015. Clarification on the Fecundity of Rhinoptera bonasus (Mitchill). Southeastern Naturalist, 14(1), N16-N20.
Smith, J. W. and Merriner, J. V. 1986. Observations on the reproductive biology of the cownose ray, Rhinoptera bonasus, in Chesapeake Bay. Fishery Bulletin, 84(4), 871-877.
McDowell, J. R. and Fisher, R. A. 2013. Discrimination of Cownose Ray, Rhinoptera bonasus, stocks based on microsatellite DNA markers. Virginia Institute of Marine Science, College of William and Mary.
Fisher, R. A. 2010. Life history, trophic ecology, and prey handling by cownose ray, Rhinoptera bonasus, from Chesapeake Bay. NOAA final report (NA07NMF4570324) Grant No. 713031 (No. 2010-20). VIMS Marine Resource Report.