Natural History of Sharks, Skates, and Rays Phylogeny of Batoidea MARE 394 Dr. Turner Summer 2009

Zoogeographic Patterns Superorder Batoidea – electric rays, sawfishes, guitarfishes, skates, & stingrays Range for polar to tropical seas 4 Orders 3 Suborders 4 Superfamilies 13 Families 6 Subfamilies 79 Genera 500 Species

Superorder Batoidea Orders: Torpediniformes – electric rays Pristiformes – sawfishes Rajiformes – true rays Mylobatiformes – eagle rays

Order Torpediniformes Family Torpedinidae – (electric rays) Family Narcinidae – (electric rays) Torpedo ray Torpedo nobiliana Numbfish Narcine maculata

Torpedinidae Family Torpedinidae – (electric rays) Torpedo ray Torpedo nobiliana Bottom dwelling, shallow coastal waters to 1,000 m Slow moving, propelling themselves along with their tails Feed on invertebrates and small fish Prey below the sand using electricity to stun and capture

Narcinidae Family Narcinidae – (electric rays) Slow-swimming bottom-dwellers that feed on small fishes and invertebrates off the bottom Generate a moderate shock if disturbed and contact is made with the electric organs Electrical discharges of narcinids have been measured at 8-37 volts, much less than the electric rays of the genus Torpedo Numbfish Narcine maculata

Order Pristiformes Family Pristidae – (sawfishes) Common sawfish Pristis pristis Although they are similar in appearance, sawsharks are distinct from sawfish. Sawfish have a much larger maximum size, lack barbels, have evenly sized rather than alternating sawteeth, and have gill slits on their undersurface rather than on the side of the head

Rhinobatos rhinobatos Order Rajiformes Family Rhinobatidae – (guitarfishes) Family Rajidae – (skates) Common guitarfish Rhinobatos rhinobatos Big Skate Raja binoculata

Rhinobatos rhinobatos Rhinobatidae Family Rhinobatidae – (guitarfishes) Common guitarfish Rhinobatos rhinobatos To 225 kg (500 lb) to 3 m (9.8 ft) in length, Ovoviviparous Bottom feeders, preferring small crustaceans Teeth are small and numerous, arranged in 65 or 70 rows Body form intermediate between those of sharks and rays Tail has a typical ray-like form, head has a triangular shape

Rajidae Family Rajidae – (skates) Benthic rays occurring in all oceans, from Arctic to Antarctic waters and from shallow coastal shelfs to abyssal regions Tail slender, 2 reduced dorsal fins and a reduced caudal fin Skin prickly in most species, the prickles often in a row along midline of dorsal Disc quadrangular to rhomboidal Five pairs of ventral gill slits Oviparous Big Skate Raja binoculata

Pteroplatytrygon violacea Order Mylobatiformes Family Platyrhinidae – (thornback ray) Family Zanobatidae – (pan rays) Family Hexatrygonidae – (longsnout stingray) Family Urolophidae – (round rays) Family Urotrygonidae – (smalleyed round ray) Family Dasyatidae – (stingrays) Family Potamotrygonidae – (river rays) Family Gymnuridae – (butterfly rays) Family Myliobatidae – (eagle rays) Spotted eagle ray Aetobatus narinari Pelagic stingray Pteroplatytrygon violacea        

Platyrhinidae Family Platyrhinidae – (thornback ray) To 1 m (3.3 ft) from 4.5 to 8.75 lb (2 to 3.98 kg) In sexually mature fish some of the spines are thickened with button-like bases (known as bucklers) Usually found on mud, sand or gravel 10-60m Feed on small crustaceans, amphipods shrimps, crabs, and small fish. Thornback ray Raja clavata

Zanobatus schoenleinii Zanobatidae Family Zanobatidae – (pan rays) Occurs in shallow coastal waters to moderate depth, over sandy and sandy-muddy bottoms Feeds on mollusks and other benthic invertebrates Ovoviviparous Striped panray Zanobatus schoenleinii

Hexatrygonidae Family Hexatrygonidae – (sixgill stingray) Snout translucent, depressed, produced and may act as an electroreceptive organ Large spiracles with external flaplike valve and well behind eyes Two serrate spines in tail; Length of disc greater than width Feeding habits unknown 6 Gill openings Sixgill stingray Hexatrygon bickelli

Urolophidae Family Urolophidae – (round rays) Well-developed caudal fin; tail moderately long; Anterior margin of pectorals continuous along side of head One or more long poisonous spines on tail Feed benthic invertebrates, copepods, amphipods, mysids Oviparous Round ray Rajella fyllae

Urotrygonidae Family Urotrygonidae – (American round stingrays) Disc width less than 1.3 times disc length Tail slender as long as the disc; No dorsal fin Distinct poisonous spines; Previously in Urolophidae Smalleyed round stingray Urotrygon microphthalmum

Pteroplatytrygon violacea Dasyatidae Family Dasyatidae – (stingrays) Chiefly marine; also in brackish and freshwater Side of head continuous with the anterior margin of pectoral fin Tail long and whip-like. venomous spine on tail, which can cause excruciating pain to humans Largest species to about 4m Ovoviviparous Pelagic stingray Pteroplatytrygon violacea        

Potamotrygonidae Family Potamotrygonidae – (river rays) Potamotrygonids are much maligned and feared because of their venomous caudal stings, but pose little or no threat if not stepped on or directly interfered with. The Potamotrygonidae is the only living chondrichthyan family restricted to freshwater habitats. Raspy river stingray Potamotrygon scobina 

Twin-spot butterfly ray Gymnuridae Family Gymnuridae – (butterfly rays) Atlantic, Indic and Pacific Oceans Marine, rarely in estuaries Outer anterior margin of pectorals continuous along side of head Dorsal fin and tail spines present or absent Disc extremely broad Tail short Twin-spot butterfly ray Gymnura bimaculata

Myliobatidae Family Myliobatidae – (eagle rays) Head elevated above disc Jaws powerful with large platelike crushing teeth Pectoral fins reduced or absent opposite the eyes Some known for their leaping ability high into the air Viviparous Spotted eagle ray Aetobatus narinari