17. class chondrichthyes notes

Class Chondrichthyes Class Chondrichthyes

““Cartilaginous Fish”Cartilaginous Fish”

Kingdom: AnimaliaKingdom: Animalia

Phylum: ChordataPhylum: Chordata

Sub Phylum: VerterbrataSub Phylum: Verterbrata

Class: ChondrichthyesClass: Chondrichthyes

Class ChondrichthyesClass Chondrichthyes

Sharks, Rays, Sharks, Rays, Skates, RatfishSkates, Ratfish

Skeleton made of Skeleton made of cartilagecartilage

General General CharacteristicsCharacteristics

Possess movable Possess movable jaws that usually jaws that usually have teethhave teeth

Mouth is ventral, Mouth is ventral, underneath the underneath the headhead

General General CharacteristicsCharacteristics Paired lateral finsPaired lateral fins

General General CharacteristicsCharacteristics Rough, sand Rough, sand

paper like skinpaper like skin Made up of Made up of

scales that have scales that have the same the same composition as composition as teethteeth

Ratfish / ChimaerasRatfish / Chimaeras

Gill slits covered Gill slits covered by a flap of skinby a flap of skin

Mostly deep-Mostly deep-water fishwater fish

Eat crustaceans Eat crustaceans and mollusksand mollusks

Skates & RaysSkates & Rays

Flattened bodiesFlattened bodies Dermersal – live Dermersal – live

on the bottomon the bottom Gill slits on the Gill slits on the

ventral side ventral side (bottom)(bottom)

Skates & RaysSkates & Rays

Pectoral fins are Pectoral fins are flat and flat and expandedexpanded

Head fuses with Head fuses with pectoral fins with pectoral fins with eyes on topeyes on top

SawfishSawfish

Ventral gill slitsVentral gill slits Swing blade Swing blade

through schools through schools disabling preydisabling prey

Similar to saw Similar to saw sharks except for sharks except for size and gill size and gill placementplacement

StingraysStingrays Equipped with a Equipped with a

stinging spinestinging spine Spine connected Spine connected

to venomous to venomous glandsglands

Teeth modified Teeth modified into grinding into grinding platesplates

Manta & Devil RaysManta & Devil Rays

Not bottom Not bottom dwellers instead dwellers instead choose to swimchoose to swim

Sharks Sharks

Living FossilsLiving Fossils Have not needed Have not needed

to evolve for 100 to evolve for 100 million yearsmillion years

MegalodonMegalodon

Ancient sharkAncient shark Largest predatory fish Largest predatory fish

everever Twice the size of a Twice the size of a

great whitegreat white

External StructureExternal Structure

Paired vs. Unpaired Paired vs. Unpaired finsfins Paired: Pectoral & PelvicPaired: Pectoral & Pelvic Comparable to our arms and legsComparable to our arms and legs Unpaired: 1Unpaired: 1stst Dorsal, 2 Dorsal, 2ndnd Dorsal, Dorsal,

Anal, and CaudalAnal, and Caudal All found along mid-lineAll found along mid-line

ScalesScales

Scales are very small and sharpScales are very small and sharp Same composition as the teethSame composition as the teeth

JawsJaws

Made of boneMade of bone Contain the Contain the

disposable teethdisposable teeth In some species In some species

capable of capable of extending jaw extending jaw out from bodyout from body

TeethTeeth

Same Same composition as composition as the scalesthe scales

Continually shed Continually shed and replaced by and replaced by the rows behindthe rows behind

RespirationRespiration

Must swim to Must swim to force water force water through their gillsthrough their gills

Some such as Some such as nurse sharks can nurse sharks can get enough get enough oxygen so they oxygen so they do not need to do not need to swimswim

DigestionDigestion

Very short Very short esophogusesophogus

Stomach can be Stomach can be up to 1/3 the up to 1/3 the length of the length of the sharkshark

Intestine is really Intestine is really small, only about small, only about a foota foot

Nervous SystemNervous System

Lateral line used for sensing vibrations Lateral line used for sensing vibrations in the waterin the water

Nervous SystemNervous System

Ampullae of LorenziniAmpullae of Lorenzini Jelly filled canals that can detect electrical Jelly filled canals that can detect electrical

fields, magnetic fields, temperature, fields, magnetic fields, temperature, salinity, water pressure, etc.salinity, water pressure, etc.

Nervous SystemNervous System

Paired external Paired external nostrils that lead nostrils that lead directly to the directly to the brainbrain

Very acute sense Very acute sense of smell, can of smell, can detect detect concentrations as concentrations as low as one part low as one part per billionper billion

Shark ClassificationShark Classification

Two Super-Orders:Two Super-Orders:– Galeomorphs & SqualomorphsGaleomorphs & Squalomorphs

Further broken down into ordersFurther broken down into orders

Order Order Heterodontiformes:Heterodontiformes:

Bullhead SharksBullhead Sharks Pig like snoutPig like snout Bottom dwellersBottom dwellers

Order Order Orectolobiformes:Orectolobiformes: ““Carpet Sharks”Carpet Sharks” Very short mouthsVery short mouths Upper lobe of Upper lobe of

caudal fin caudal fin extended with extended with reduced lower reduced lower lobelobe

Includes filter Includes filter feedersfeeders

Order Lamniformes:Order Lamniformes:

““Mackerel Fish”Mackerel Fish” Larger front teethLarger front teeth Include some of Include some of

most popularmost popular Most are active Most are active

predatorspredators Functionally Functionally

warm-bloodedwarm-blooded

Order Lamniformes:Order Lamniformes:

““Goblin Sharks”Goblin Sharks” MitsukurindidaeMitsukurindidae

““Sandtiger Sandtiger Sharks”Sharks”

CarchariidaeCarchariidae

Order Lamniformes:Order Lamniformes:

““Ragged-Tooth Ragged-Tooth Sharks”Sharks”

OdontaspididaeOdontaspididae

““Thresher Thresher Sharks”Sharks”

AlopiidaeAlopiidae

Order Lamniformes:Order Lamniformes:

““Megamouth Megamouth Shark”Shark”

MegachasmidaeMegachasmidae

““Crocodile Crocodile Sharks”Sharks”

PseudocarchariidaPseudocarchariidaee

Order Lamniformes:Order Lamniformes:

““Basking Shark”Basking Shark” CetorhinidaeCetorhinidae

““Mackerel Mackerel Sharks”Sharks”

LamnidaeLamnidae

Order Order Carcharhiniformes:Carcharhiniformes:

““Ground or Ground or Whaler Sharks”Whaler Sharks”

Adaptable to Adaptable to many many environments, environments, even estuarine even estuarine and freshwater and freshwater

Flappable lower Flappable lower eyelidseyelids

Order Order Carcharhiniformes:Carcharhiniformes: ““Whaler Sharks”Whaler Sharks” CarcharhinidaeCarcharhinidae

““Hammerhead Hammerhead Sharks”Sharks”

SphyrnidaeSphyrnidae

Order Order Carcharhiniformes:Carcharhiniformes:

““Cat Sharks”Cat Sharks” SchliorhinidaeSchliorhinidae

Order ChlamydoselachiOrder Chlamydoselachi

““Frilled Shark”Frilled Shark” Eel like bodyEel like body Teeth are three Teeth are three

prongedpronged Deep waterDeep water

Order HexanchiformesOrder Hexanchiformes

““Cow Sharks”Cow Sharks” Deep waterDeep water Very little is knownVery little is known

Order Order EchinorhiniformesEchinorhiniformes ““Bramble Sharks”Bramble Sharks” Thick tail stalkThick tail stalk Has bumps on skinHas bumps on skin ““hedgehog sharkhedgehog shark

Order SqauliformesOrder Sqauliformes

““Dogfish Sharks”Dogfish Sharks” Large ranges of sizesLarge ranges of sizes Generally best known sharkGenerally best known shark

Order SqauliformesOrder Sqauliformes

Greenland Shark Greenland Shark (21 feet +)(21 feet +)

Dwarf Dwarf LaternsharkLaternshark

Order SquantiniformesOrder Squantiniformes

““Angel Sharks”Angel Sharks” Flattened bodiesFlattened bodies Gills on ventral sideGills on ventral side Mouth at end rather than ventral like rays Mouth at end rather than ventral like rays

and skatesand skates

Order Order PristiophoriformesPristiophoriformes

““Sawsharks’Sawsharks’ Similar to Similar to

sawfish, but sawfish, but skinnier and skinnier and have sensitive have sensitive barbs on snoutbarbs on snout

Alternating long Alternating long short teethshort teeth