Post on 02-Jan-2016
description
Natural History of Sharks, Skates, and Rays
Phylogeny of Batoidea
MARE 380Dr. Turner
Zoogeographic PatternsSuperorder Batoidea – electric rays, sawfishes, guitarfishes, skates, & stingrays
Range for polar to tropical seas
4 Orders3 Suborders4 Superfamilies13 Families6 Subfamilies79 Genera500 Species
Superorder BatoideaOrders: Torpediniformes – electric raysPristiformes – sawfishesRajiformes – true raysMylobatiformes – eagle rays
Order TorpediniformesFamily Torpedinidae – (electric rays)
Family Narcinidae – (electric rays)
Torpedo rayTorpedo nobiliana
NumbfishNarcine maculata
TorpedinidaeFamily Torpedinidae – (electric rays)
Torpedo rayTorpedo 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
NarcinidaeFamily Narcinidae – (electric rays)
NumbfishNarcine maculata
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
Order PristiformesFamily Pristidae – (sawfishes)
Common sawfishPristis 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
Order RajiformesFamily Rhinobatidae – (guitarfishes)
Family Rajidae – (skates)
Common guitarfishRhinobatos rhinobatos
Big SkateRaja binoculata
RhinobatidaeFamily Rhinobatidae – (guitarfishes)
Common guitarfishRhinobatos 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
RajidaeFamily Rajidae – (skates)
Big SkateRaja binoculata
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
Order MylobatiformesFamily 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)
Pelagic stingrayPteroplatytrygon violacea
Spotted eagle rayAetobatus narinari
PlatyrhinidaeFamily 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
ZanobatidaeFamily Zanobatidae – (pan rays)
Striped panray Zanobatus schoenleinii
Occurs in shallow coastal waters to moderate depth, over sandy and sandy-muddy bottoms
Feeds on mollusks and other benthic invertebrates
Ovoviviparous
HexatrygonidaeFamily 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 stingrayHexatrygon bickelli
UrolophidaeFamily 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 rayRajella fyllae
UrotrygonidaeFamily 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 stingrayUrotrygon microphthalmum
DasyatidaeFamily Dasyatidae – (stingrays)
Pelagic stingrayPteroplatytrygon violacea
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
PotamotrygonidaeFamily 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 stingrayPotamotrygon scobina
GymnuridaeFamily 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
MyliobatidaeFamily Myliobatidae – (eagle rays)
Spotted eagle rayAetobatus narinari
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