chondrichthyes (1)

ChondrichthyesChondrichthyes

Cartilaginous FishCartilaginous Fish

CharacteristicsCharacteristics

• Endoskeleton entirely cartilaginousEndoskeleton entirely cartilaginous• Fusiform BodyFusiform Body• Mouth VentralMouth Ventral• Skin with placoid scalesSkin with placoid scales• 2 chambered heart2 chambered heart• Separate exposed gill slitsSeparate exposed gill slits• No operculumNo operculum• Heterocercal tailHeterocercal tail• Internal reproduction (claspers & cloaca)Internal reproduction (claspers & cloaca)

Fusiform bodyFusiform body

• Torpedo shapeTorpedo shape

• Sharks have Sharks have countershading countershading (Dark on top & (Dark on top & light on the light on the bottom)bottom)

Placoid ScalesPlacoid Scales

• These scales These scales point towards the point towards the tail and helps to tail and helps to reduce friction reduce friction from surrounding from surrounding water when the water when the shark swimsshark swims

Shark AnatomyShark Anatomy

Shark AnatomyShark Anatomy

Shark SensesShark Senses

smell    hearing    lateral line organ     vision     ampullae of Lorenzini     touch and taste 

How a Shark EatsHow a Shark Eats

Two chambered heartTwo chambered heart

Gill SlitsGill Slits

Lack operculumLack operculum

Heterocercal vs Heterocercal vs HomocercalHomocercal

• Sharks have Sharks have heterocercal heterocercal caudal fins with caudal fins with the vertebrae the vertebrae extending into the extending into the superior region of superior region of the caudal finthe caudal fin

Shark ReproductionShark Reproduction

• Male claspers are Male claspers are inserted into inserted into female cloaca for female cloaca for internal internal fertilizationfertilization

• Ovoviviparous Ovoviviparous 90% 90%

• Viviparous (Great Viviparous (Great whites)whites)

• OviparousOviparous

Female Reproductive Female Reproductive AnatomyAnatomy

Male Reproductive Male Reproductive AnatomyAnatomy

Chondrichthyes Chondrichthyes ReproductionReproduction

• oviparousoviparous (laying eggs that hatch outside the (laying eggs that hatch outside the mother's body) mother's body)

• ovoviviparousovoviviparous (brooding eggs that hatch within (brooding eggs that hatch within the mother's body, and then releasing the young) the mother's body, and then releasing the young)

• viviparousviviparous (young develop within a uterus inside (young develop within a uterus inside the mother's body, and are nourished prior to birth the mother's body, and are nourished prior to birth via a connection with the mother's bloodstream via a connection with the mother's bloodstream (placenta).(placenta).

Cat Shark Egg

Oviparous

Dogfish Shark embryos

Ovoviviparous

Porbeagle embryo viviparous

Characteristics con’tCharacteristics con’t

• No swimbladder or lungNo swimbladder or lung• 2 olfactory lobes2 olfactory lobes• 2 cerebral hemispheres2 cerebral hemispheres• 2 optic lobes2 optic lobes• 1 cerebellum1 cerebellum• 1 medulla oblongata1 medulla oblongata• 3 pairs of semicircular canals3 pairs of semicircular canals• Ampullary organs of LorenziniAmpullary organs of Lorenzini

SwimbladderSwimbladder

• Sharks lack a swimbladder

• Oil in the liver is used to change buoyancy

Tapetum lucidumTapetum lucidum

Reflects light in the eye

Lateral Line SystemLateral Line System

Whale SharkWhale Shark

Worlds largest fish

(46 ft long)

Not many fossilsNot many fossils • Guitarfish Guitarfish

(One of the few (One of the few chondricthyes fossils)chondricthyes fossils)

ElasmobranchiiElasmobranchii

• Includes the familiar sharks, Includes the familiar sharks, skates, and rays, as well as skates, and rays, as well as some strange fossil relatives.some strange fossil relatives.

• Elasmobranchs have an upper Elasmobranchs have an upper jaw that is not fused to the jaw that is not fused to the braincase and separate slit-braincase and separate slit-like gill openings. like gill openings.

Rays & SkatesRays & Skates

Rays & SkatesRays & Skates• Rays and Skates, unlike sharks, are not fusiform, but Rays and Skates, unlike sharks, are not fusiform, but

dorsoventrally flattened. dorsoventrally flattened.

• Gill slits open on the ventral surface of the head Gill slits open on the ventral surface of the head

• Spiracles on the top of the head direct water over the Spiracles on the top of the head direct water over the gills, to prevent sludge from clogging these delicate gills, to prevent sludge from clogging these delicate structures structures

• They feed primarily on mollusks and crustaceans, and They feed primarily on mollusks and crustaceans, and so have teeth modified for crushing.so have teeth modified for crushing.

Skates vs RaysSkates vs Rays

• The major difference between skates The major difference between skates and rays is the way in which they and rays is the way in which they reproduce.reproduce.

•     • Rays are viviparous (live bearing)Rays are viviparous (live bearing)

• Skates are oviparous (egg laying), Skates are oviparous (egg laying), releasing their eggs in rectangular releasing their eggs in rectangular cases sometimes called "mermaid´s cases sometimes called "mermaid´s purses".purses".

Mermaid purseMermaid purse

BradyodontiBradyodonti

• Includes forms with an upper jaw fused Includes forms with an upper jaw fused to the braincase and a flap of skin, the to the braincase and a flap of skin, the operculum, covering the gill slits. operculum, covering the gill slits.

• The Bradyodonti includes the The Bradyodonti includes the chimaeras and ratfish, which are chimaeras and ratfish, which are relatively rare, deep-water, mollusc-relatively rare, deep-water, mollusc-eating forms. eating forms.

ChimaeraChimaera

RatfishRatfish