1. Class Chondrichthyes
“Cartilage Fish”

2. Class Chondrichthyes Two sub-classes Elasmobranchii Holocephali Sharks
Rays
Skates
Holocephali
Rat fish
Rabbit fish
Parrot fish

3. Class Chondrichthyes Most are marine Most are active predators
Few plankton eaters (whale & basking sharks)

4. Relationship to Humans
Used for food
Liver oil
Clothing
Jewelry
Competition fishing

5. Characteristics Paired Fins Tough placoid scales: “placoderms”
Provide protection
Aid in streamlining
Some species secrete mucous

6. Characteristics Powerful jaws, multiple rows of replaceable teeth
Great white bites with force greater than a shot from rifle
Mouth is ventral
Heterocercal tail – unequally divided

7. Characteristics Skeleton – cartilaginous, with no true bones
Notochord present in young
No ribs – larger species die when taken from water due to body weight on organs
2 chambered heart (atrium & ventricle)
Closed circulatory
Heart is ventral, in head region
Blood pumped through aorta to gills, then to body tissues, back to heart through veins

8. Characteristics
Cold blooded – “poikilothermic” – internal body temp. can have wide range
Body temp matches the environment
Reproduction
Dioecious, with internal fertilization
Dogfish & rays are oviparous
Most species are viviparous

9. Characteristics Wide range of sizes Dogfish= 3ft Great white= 20 ft
Basking shark= 40 ft
Whale shark= 45+ft (largest fish)

10. Characteristics Nervous system: well developed brain
Olfactory – 2 nostrils for taste/smell
Optic – well developed eyesight
Auditory – Ears inside body, well developed; works with…
Lateral line – sensory openings along length of body, pick up low frequency vibrations

11. Characteristics Nervous system cont…
Electromagnetic receptors= “ampullae of lorenzini”
Detects electric currents given off by any living thing
May help orient animal to earths electromagnetic field

12. Characteristics Respiration 5-7 gill pairs
Most species have spiracles just behind eyes
Provide direct oxygen supply to eyes