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Download Class Chondrichthyes - Valhalla High School
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Class Chondrichthyes “Cartilage Fish” Class Chondrichthyes • Two sub-classes – Elasmobranchii • Sharks • Rays • Skates – Holocephali • Rat fish • Rabbit fish • Parrot fish Class Chondrichthyes • Most are marine • Most are active predators – Few plankton eaters (whale & basking sharks) Relationship to Humans • • • • • Used for food Liver oil Clothing Jewelry Competition fishing Characteristics • Paired Fins • Tough placoid scales: “placoderms” – Provide protection – Aid in streamlining – Some species secrete mucous Characteristics • Powerful jaws, multiple rows of replaceable teeth – Great white bites with force greater than a shot from 30-06 rifle • Mouth is ventral • Heterocercal tail – unequally divided 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 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 Characteristics • Wide range of sizes – Dogfish= 3ft – Great white= 20 ft – Basking shark= 40 ft – Whale shark= 45+ft (largest fish) 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 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 Characteristics • Respiration – 5-7 gill pairs – Most species have spiracles just behind eyes • Provide direct oxygen supply to eyes
