Natural History of Sharks, Skates, and Rays

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Natural History of Sharks, Skates, and
Rays Phylogeny of Batoidea MARE 380 Dr. Turner
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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
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Superorder Batoidea
Orders Torpediniformes electric
rays Pristiformes sawfishes Rajiformes true
rays Mylobatiformes eagle rays
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Order Torpediniformes
Family Torpedinidae (electric rays) Family
Narcinidae (electric rays)
Torpedo ray Torpedo nobiliana
Numbfish Narcine maculata
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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
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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
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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
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Order Rajiformes
Family Rhinobatidae (guitarfishes) Family
Rajidae (skates)
Common guitarfish Rhinobatos rhinobatos
Big Skate Raja binoculata
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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
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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
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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    
   
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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
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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 Ovovi
viparous
Striped panray Zanobatus schoenleinii
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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
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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
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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
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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    
   
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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 
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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
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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