Transcript Slide 1

Lancelets
Amphioxiformes: Branchiostomatidae
* branchio = gill (G)
* stom = mouth (G)
Hagfishes
Myxiniformes: Myxinidae
myxin = slime (G)
Lampreys
Petromyzontiformes: Petromyzontidae
petra = stone (L) + myzo = to suckle (G) + odontos = teeth (G)
Elasmo-sources
Bulleted lists and cladogram that follow ref:
Martin, R. Aidan. 2003.
ReefQuest Centre for Shark Research Home.
World Wide Web Publication,
www.elasmo-research.org/index.html
Chimaeras
Chimaeriformes: Chimaeridae
• Gill cover over the four gills, leaving a single opening on each side of the head
• palatoquadrate (upper jaw) is usually fused to the cranium
• no spiracle opening behind the eye
• branchial (gill) basket mostly beneath the neurocranium (posterior part of the
cranium that encases the brain)
• teeth relatively few (one pair in the lower jaw and two pairs in the upper),
occurring as mineralized grinding plates
• tooth plate replacement is slow
• no cloaca, but with separate anal and urogenital openings
• skin in adults 'naked' (without dermal denticles)
• no stomach or ribs
• males - in addition to the pelvic claspers - have an accessory clasping organ on
the head
Chimaeras
Chimaeriformes: Chimaeridae
* single gill opening rather than multiple
Carpet Sharks
Orectolobiformes
•two, spineless dorsal fins
•a very short, transverse mouth that is well anterior to the eyes
•specialized nostrils, with prominent barbels and nasoral grooves connecting the
nostrils to the mouth corners in most forms
•spiracles small to very large, located below the eye
•most with small gill slits, with the fourth overlapping the fifth and behind origin of
the pectoral fin
•most species have a caudal fin with an upper lobe that is more-or-less in line with
the main body axis (not tilted upward, as in most other sharks) and a poorlydeveloped lower lobe; the order's scientific name translates roughly to "stretched-out
lobe", in reference to the tail type characteristic of the group
•13 genera in 8 families
Note: Whale Sharks, the only fully pelagic orectolobid,
are exceptions to many of these rules.
Carpet Sharks
Orectolobiformes: Ginglymostomatidae – Nurse Sharks
ginglymo = hinge (G) stom = mouth (G)
Carpet Sharks
Orectolobiformes: Stegostomatidae – Zebra Sharks
Stegos = roof, house, from; stegein = to cover (G) stoma = mouth (G)
Carpet Sharks
Orectolobiformes: Rhincodontidae – Whale Sharks
rhyngchos = snout, muzzle (G) + odous, odontos = tooth, teeth (G)
Requiem Sharks
Carchariniformes
•two dorsal fins (except in the scyliorhinid Pentanchus profundicolus,
which has only one), without spines
•anal fin present
•five gill slits, with the last one to three over the pectoral fin base
•eyes with nictitating fold or membrane (moveable lower eyelid)
•intestinal valve of spiral or scroll type
•found in virtually every marine habitat, many species occur in estuarine
areas and a few make use of freshwater habitats as well; they range from
coastal areas to the open ocean, in temperate to tropical zones of the
Atlantic, Pacific, and Indian oceans
•at least 49 genera in 9 families (possibly as many as 60 genera in 14
families)
Requiem Sharks
Carchariniformes: Scyliorhinidae – Cat Sharks
skylla = a shark (G) + rhinos = nose (G)
Requiem Sharks
Carchariniformes: Triakidae – Hound Sharks
Triakis = thrice (G)
Requiem Sharks
Carchariniformes: Carcharinidae – Requiem Sharks, Tiger Sharks, Reef Sharks
karcharos = cutting, sharp, also a kind of shark (G) + rhinos = nose (G)
Requiem Sharks
Carchariniformes: Sphyrnidae – Hammerhead Sharks
sphyr = hammer (G)
Mackerel Sharks
Lamniformes
•two dorsal fins, without spines
•anal fin present
•five pairs of gill slits, either entirely in front of the pectoral fin base or with the
last two above the pectoral base
•spiracles usually present, small and behind eyes
•eyes without nictitating membrane
•mouth subterminal, jaws extending well behind the eyes
•upper teeth well differentiated along the jaws forming the so-called "lamnoid
dental pattern" which features enlarged anterior teeth, slightly to much smaller
intermediate teeth, large lateral teeth, followed by much smaller posterior teeth
•intestinal valve of ring type
•exclusively marine, in coastal to open-ocean environments; they inhabit cold
temperate to tropical zones of the Atlantic, Pacific, and Indian Oceans
•10 genera in 8 families
Mackerel Sharks
Lamniformes: Lamnidae – Mackerel Sharks
lamna = shark (G)
Mackerel Sharks
Lamniformes: Cetorhinidae – Basking Shark
cetus = whale, marine monster (L) + rhinos = nose (G)
Mackerel Sharks
Lamniformes: Odontaspididae – Sand Tiger Shark
odont = teeth (G) aspid = viper (G)
Dogfish Sharks
Squaliformes
•five pairs of gill slits
•two dorsal fins, often with a spine along the leading edge; the first
dorsal originates in front of pelvic fin origins
•lack of an anal fin
•many species are bioluminescent to some degree
•ovoviviparous
•exclusively marine; most species are strongly bottom oriented,
although many mesopelagic forms undertake nightly vertical
migrations; a successful and widely distributed group, dogfishes
inhabit coastal and oceanic waters, mostly in cool temperate to deep
tropical waters in both hemispheres, but ranging from the Antarctic to
the Arctic
•22 genera in 6 families
Dogfish Sharks
Squaliformes: Squalidae – Dogfishes
squaleo, squalidus = with rough skin (L)
Dogfish Sharks
(Squaliformes: Somniosidae) – Sleeper Sharks
Now Squaliformes: Dalatiidae
dalos, -ou = torch (G)
Skates & Rays (Batoids)
Rajiformes: Pristidae now Pristiformes:Pristidae
•snout saw-like with equal-sized, strongly-embedded teeth
along margin; nasal barbels absent
•body shark-like
•two distinct dorsal fins and a caudal fin
•ovoviviparous
•mostly marine, although the largetooth sawfish (Pristis
microdon) ascends some rivers in Australia and New Guinea
•2 genera (Pristis and Anoxypristis) in the family Pristidae
prist = sawed (G)
Skates & Rays
Rajiformes: Pristidae – Sawfishes
prist = sawed (G)
Skates & Rays
Rajiformes: Torpedinidae
or Torpediniformes: Torpedinidae
•rounded snout and pectoral disc
•large, kidney-shaped electrogenic organs (derived from branchial
musculature) at base of pectoral fins
•body thick and flabby, with soft, loose skin
•eyes small to obsolete (four species are blind)
•0 to 2 dorsal fins, depending upon species
•caudal fin well developed
•ovoviviparous
•exclusively marine, inhabiting temperate to tropical zones of the
Atlantic, Pacific, and Indian oceans
•11 genera in 4 families
Skates & Rays
Rajiformes: Torpedinidae – Electric rays
torped = numb, paralysis (L)
Skates & Rays
Rajiformes: Rajidae
•snout pointed
•pectoral disc usually rhomboid
•tail slender, set off from pectoral disc
•caudal fin moderately well developed, reduced or absent; weak electrogenic
organs at base of tail stalk (derived from caudal peduncle muscles)
•0 to 2 dorsal fins
•most with enlarged, thorn-like denticles ('bucklers') on skin, often with a row
along midline of back
•oviparous
•almost exclusively marine; a few species live in shallow waters close to shore,
but most live in deep water, on soft bottoms along continental margins, down
to 8 840 feet (3 000 metres) or more
•26 genera in a single family (Rajidae), divided into 2 subfamilies
Skates & Rays
Rajiformes: Rajidae – Skates
Raja = ray (L)
Skates & Rays
Order Myliobatiformes: Stingrays - 178 species
•pectoral disc rhomboid, oval, or triangular in outline, elaborated into
gracefully-shaped wings in some forms
•tail moderately stout to very slender
•caudal fin and a single dorsal fin are variably present or absent, depending on
species
•most species have one or more saw-edged spines or stings on the dorsal surface
of the tail (the sting is a modified dermal denticle, sheathed with poisonous
tissue and used as a defensive weapon)
•most forms have five pairs of gill slits, but members of the family
Hexatrygonidae have six
•ovoviviparous
•temperate to tropical zones of the Atlantic, Pacific, and Indian oceans; most
species are marine, but some enter brackish or fresh waters and the river
stingrays (family Potamotrygonidae) are exclusively freshwater inhabitants,
having lost the ability to osmoregulate in the sea
•33 genera in 10 families
Skates & Rays
Rajiformes: Dasyatidae – Stingrays
dasys = hair (G)
Skates & Rays
Rajiformes: Gymnuridae – Butterfly Rays
gymnos = naked (G) + uro = tail (G)
Skates & Rays
Rajiformes: Myliobatidae – Eagle Rays
myleys = mill, millstone (G) + batis = ray (G)
Skates & Rays
(Rajiformes: Mobulidae – Manta Rays)
Now lumped with Myliobatidae
Coelacanth
Coelacanthiformes: Coelacanthidae – Coelacanths
coel = hollow (G) acanth = spine (G)
Lungfish
Lepidosireniformes: Protopteridae – African Lungfish
pro = before, in front of (G) + pteron = fin (G)
Reedfishes & Bichirs
Polypteriformes: Polypteridae – Bichir
poly = many (G)
pteri = fin (G)
Sturgeons & Paddlefishes
Acipenseriformes:
Acipenseridae – Sturgeons
acipenser = sturgeon (L)
Sturgeons & Paddlefishes
Acipenseriformes: Polyodontidae – Paddlefishes
poly = many (G) odont = teeth (G)
Gars
Semiontiformes: Lepisosteidae – Gars
lepis, -idos = scale (G) + osteon = bone (G)
Bowfin
Amiiformes: Amiidae
amia = A kind of fish, probably the perch or the bonito (G)
Bonytongues
Osteoglossiformes: Osteoglossidae – Bonytongues
osteon = bone (G) + glossa = tongue (G) + forma = shape (L)
Bonytongues
Osteoglossiformes: Pantodontidae – Butterflyfishes
pan = all (G) + odous = tooth, teeth (G)
Bonytongues
Osteoglossiformes: Notopteridae – African Knifefishes
noton = back (G) + pteron = wing, fin (G)
Bonytongues
Osteoglossiformes: Mormyridae – Elephantnose Fishes
mormyros = a kind of fish (G)