Chondrichthyes Cartilaginous Fish

Characteristics 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 body Torpedo shapeTorpedo shape Sharks have countershading (Dark on top & light on the bottom)Sharks have countershading (Dark on top & light on the bottom)

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

Shark Anatomy

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

How a Shark Eats

Two chambered heart

Gill Slits

Lack operculum

Heterocercal vs Homocercal Sharks have heterocercal caudal fins with the vertebrae extending into the superior region of the caudal finSharks have heterocercal caudal fins with the vertebrae extending into the superior region of the caudal fin

Shark Reproduction Male claspers are inserted into female cloaca for internal fertilizationMale claspers are inserted into female cloaca for internal fertilization Ovoviviparous 90%Ovoviviparous 90% Viviparous (Great whites)Viviparous (Great whites) OviparousOviparous

Female Reproductive Anatomy

Male Reproductive Anatomy

Chondrichthyes Reproduction oviparous (laying eggs that hatch outside the mother's body)oviparous (laying eggs that hatch outside the mother's body) ovoviviparous (brooding eggs that hatch within the mother's body, and then releasing the young)ovoviviparous (brooding eggs that hatch within the mother's body, and then releasing the young) viviparous (young develop within a uterus inside the mother's body, and are nourished prior to birth via a connection with the mother's bloodstream (placenta).viviparous (young develop within a uterus inside the mother's body, and are nourished prior to birth via a connection with the mother's bloodstream (placenta).

Cat Shark Egg Oviparous Dogfish Shark embryos Ovoviviparous Porbeagle embryo viviparous

Characteristics 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

Swimbladder Sharks lack a swimbladder Oil in the liver is used to change buoyancy

Tapetum lucidum Reflects light in the eye

Lateral Line System

Whale Shark Worlds largest fish (46 ft long)

Not many fossils GuitarfishGuitarfish (One of the few chondricthyes fossils)

Elasmobranchii Includes the familiar sharks, skates, and rays, as well as some strange fossil relatives.Includes the familiar sharks, skates, and rays, as well as some strange fossil relatives. Elasmobranchs have an upper jaw that is not fused to the braincase and separate slit-like gill openings. Elasmobranchs have an upper jaw that is not fused to the braincase and separate slit-like gill openings.

Rays & Skates

Rays and Skates, unlike sharks, are not fusiform, but dorsoventrally flattened.Rays and Skates, unlike sharks, are not fusiform, but dorsoventrally flattened. Gill slits open on the ventral surface of the headGill slits open on the ventral surface of the head Spiracles on the top of the head direct water over the gills, to prevent sludge from clogging these delicate structuresSpiracles on the top of the head direct water over the gills, to prevent sludge from clogging these delicate structures They feed primarily on mollusks and crustaceans, and so have teeth modified for crushing.They feed primarily on mollusks and crustaceans, and so have teeth modified for crushing.

Skates vs Rays The major difference between skates and rays is the way in which they reproduce.The major difference between skates and rays is the way in which they reproduce. Rays are viviparous (live bearing)Rays are viviparous (live bearing) Skates are oviparous (egg laying), releasing their eggs in rectangular cases sometimes called "mermaid´s purses".Skates are oviparous (egg laying), releasing their eggs in rectangular cases sometimes called "mermaid´s purses".

Mermaid purse

Bradyodonti Includes forms with an upper jaw fused to the braincase and a flap of skin, the operculum, covering the gill slits.Includes forms with an upper jaw fused to the braincase and a flap of skin, the operculum, covering the gill slits. The Bradyodonti includes the chimaeras and ratfish, which are relatively rare, deep-water, mollusc-eating forms.The Bradyodonti includes the chimaeras and ratfish, which are relatively rare, deep-water, mollusc-eating forms.

Chimaera

Ratfish