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Class Chondrichthyes 1 Sharks, Skates, Rays and Chimeras
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Class Chondrichthyes 2 Subclass Elasmobranchii Sharks Skates and Rays Subclass Holocephali Chimaeras (Ratfish) Traits Habitats
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Class Chondrichthyes 3 Adaptations Buoyancy Respiration External covering Feeding Movement Sensory systems
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Class Chondrichthyes 4 Buoyancy Huge oil-filled liver A shark that has an air weight of 1,000 kg. weighs only 3.3kg in water Lift created by a heterocercal tail
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Class Chondrichthyes 5 Caudal Fin Types Homocercal Heterocercal
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Class Chondrichthyes 6 Respiration Chondrichthyes employ 3 different methods of respiration “Two pump” method Ram ventilation Spiracles
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Class Chondrichthyes 7
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8 External Covering All Chondrichthyes have placoid scales in one form or another Placoid scale modifications Spine of stingray, dorsal spine of dogfish, defensive spines in the skate, and teeth
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Class Chondrichthyes 9 Scale Types Placoid:Sharks, Skates and Rays Cycloid: Tarpon and Ladyfish Ganoid: Sturgeon & Paddlefish Ctenoid
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Class Chondrichthyes 10 Feeding Most are specialized predators and have dentition that reflects their lifestyle Sharks that prey on fish and marine mammals have triangular blade-like teeth oUsed for grabbing and tearing oCan exert biting pressures of 2,800 kg/cm 3 Teeth are constantly being shed and replaced oUp to 30,000 in a lifetime
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Class Chondrichthyes 12 Feeding Digestion Spiral valve
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Class Chondrichthyes 13 Movement Pelagic sharks have rete mirabile
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Class Chondrichthyes 14 Sensory Systems Elasmobranchs a have well-developed sensory system which acts in concert to locate prey and find their way around the environment Some species can detect a drop of blood as dilute as 1 part per billion Also, very good at following an odor trail
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Class Chondrichthyes 15 Sensory Systems Hearing Olfaction Lateral line
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Class Chondrichthyes 16 Sensory Systems Visual systems are well developed for use during night and day Tapetum lucidum = increased vision at night Nictitating membrane
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Class Chondrichthyes 17 Sensory Systems Ampullae of Lorenzini
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Class Chondrichthyes 19 Chondrichthyes Reproduction Most species have extended gestation periods in egg cases or in the body cavities of females Young traits Internal fertilization, through the use of claspers on the male
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Class Chondrichthyes 20 Chondrichthyes Reproduction Oviparity Viviparity Yolk-sac Viviparity Uterine Viviparity Cannibal Viviparity Placental Viviparity
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Class Chondrichthyes 21 Oviparity - Egg Laying Oviparity
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Class Chondrichthyes 22 Viviparity Yolk-sac Viviparity (Ovoviviparity) Eggs are produced and retained inside the mother Shell disappears and young are retained until fully developed Uterine Viviparity Mother secretes nutrient rich fluid which is taken up through the skin of the embryo
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Class Chondrichthyes 23 Cannibal Viviparity Young in each oviduct consume unfertilized eggs or other siblings
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Class Chondrichthyes 24 Placental Viviparity Nutrients are supplied to the embryo directly from the mother via a umbilical cord
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Class Chondrichthyes 26 Chondrichthyes Life History Strategy of Elasmobranchs Produce precocial young with high survival rates Slow growing, long lived, and reach sexual maturity at a late age This reproductive strategy is why elasmobranchs can not sustain an intensive fishery
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Class Chondrichthyes 27 Class Chondrichthyes Subclass Holocephali Possess cartilaginous skeleton, intromittent organs, spiral valve intestine, and oil filled liver As a group found mostly between 80- 2,600 meters, feeding on hard shelled invertebrates
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