Amphioxiformes: Branchiostomatidae Lancelets

* branchio = gill (G) * stom = mouth (G)

HagfishesMyxiniformes: Myxinidae

myxin = slime (G)

LampreysPetromyzontiformes: 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

ChimaerasChimaeriformes: 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

ChimaerasChimaeriformes: Chimaeridae

* single gill opening rather than multiple

Carpet SharksOrectolobiformes

•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 poorly-developed 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 SharksOrectolobiformes: Ginglymostomatidae – Nurse Sharks

ginglymo = hinge (G) stom = mouth (G)

Carpet SharksOrectolobiformes: Stegostomatidae – Zebra Sharks

Stegos = roof, house, from; stegein = to cover (G) stoma = mouth (G)

Carpet SharksOrectolobiformes: Rhincodontidae – Whale Sharks

rhyngchos = snout, muzzle (G) + odous, odontos = tooth, teeth (G)

Requiem SharksCarchariniformes

•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 SharksCarchariniformes: Scyliorhinidae – Cat Sharks

skylla = a shark (G) + rhinos = nose (G)

Requiem SharksCarchariniformes: Triakidae – Hound Sharks

Triakis = thrice (G)

Requiem SharksCarchariniformes: Carcharinidae – Requiem Sharks, Tiger Sharks, Reef Sharks

karcharos = cutting, sharp, also a kind of shark (G) + rhinos = nose (G)

Requiem SharksCarchariniformes: Sphyrnidae – Hammerhead Sharks

sphyr = hammer (G)

Mackerel SharksLamniformes

•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 SharksLamniformes: Lamnidae – Mackerel Sharks

lamna = shark (G)

Mackerel SharksLamniformes: Cetorhinidae – Basking Shark

cetus = whale, marine monster (L) + rhinos = nose (G)

Mackerel SharksLamniformes: Odontaspididae – Sand Tiger Shark

odont = teeth (G) aspid = viper (G)

Dogfish SharksSqualiformes

•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 SharksSqualiformes: Squalidae – Dogfishes

squaleo, squalidus = with rough skin (L)

Dogfish Sharks

dalos, -ou = torch (G)

(Squaliformes: Somniosidae) – Sleeper Sharks

Now Squaliformes: Dalatiidae

Skates & Rays (Batoids)Rajiformes: Pristidae now Pristiformes:Pristidae

prist = sawed (G)

•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

Skates & RaysRajiformes: Pristidae – Sawfishes

prist = sawed (G)

Skates & RaysRajiformes: 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 & RaysRajiformes: Torpedinidae – Electric rays

torped = numb, paralysis (L)

Skates & RaysRajiformes: 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 & RaysRajiformes: Rajidae – Skates

Raja = ray (L)

Skates & RaysOrder 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 & RaysRajiformes: Dasyatidae – Stingrays

dasys = hair (G)

Skates & RaysRajiformes: Gymnuridae – Butterfly Rays

gymnos = naked (G) + uro = tail (G)

Skates & RaysRajiformes: Myliobatidae – Eagle Rays

myleys = mill, millstone (G) + batis = ray (G)

Skates & Rays(Rajiformes: Mobulidae – Manta Rays)

Now lumped with Myliobatidae

CoelacanthCoelacanthiformes: Coelacanthidae – Coelacanths

coel = hollow (G) acanth = spine (G)

LungfishLepidosireniformes: Protopteridae – African Lungfish

pro = before, in front of (G) + pteron = fin (G)

Reedfishes & BichirsPolypteriformes: Polypteridae – Bichir

poly = many (G) pteri = fin (G)

Sturgeons & PaddlefishesAcipenseriformes:

Acipenseridae – Sturgeons

acipenser = sturgeon (L)

Sturgeons & PaddlefishesAcipenseriformes: Polyodontidae – Paddlefishes

poly = many (G) odont = teeth (G)

GarsSemiontiformes: Lepisosteidae – Gars

lepis, -idos = scale (G) + osteon = bone (G)

BowfinAmiiformes: Amiidae

amia = A kind of fish, probably the perch or the bonito (G)

BonytonguesOsteoglossiformes: Osteoglossidae – Bonytongues

osteon = bone (G) + glossa = tongue (G) + forma = shape (L)

BonytonguesOsteoglossiformes: Pantodontidae – Butterflyfishes

pan = all (G) + odous = tooth, teeth (G)

BonytonguesOsteoglossiformes: Notopteridae – African Knifefishes

noton = back (G) + pteron = wing, fin (G)

BonytonguesOsteoglossiformes: Mormyridae – Elephantnose Fishes

mormyros = a kind of fish (G)