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JAWS Teeth are modified scales Teeth are modified scales Bottom jaw is like a fork for grabbing and holding prey Bottom jaw is like a fork for grabbing.

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Presentation on theme: "JAWS Teeth are modified scales Teeth are modified scales Bottom jaw is like a fork for grabbing and holding prey Bottom jaw is like a fork for grabbing."— Presentation transcript:

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2 JAWS Teeth are modified scales Teeth are modified scales Bottom jaw is like a fork for grabbing and holding prey Bottom jaw is like a fork for grabbing and holding prey Top jaw is like a knife with serrated edges to cut through prey Top jaw is like a knife with serrated edges to cut through prey Bite strength: 132 lbs. between jaws = 22 tons/in 2 at tips of teeth! Bite strength: 132 lbs. between jaws = 22 tons/in 2 at tips of teeth!

3 BODY Fusiform body Fusiform body Usually countershaded Usually countershaded

4 CAUDAL FINS Homocercal: top and bottom lobes are equal in length (GWS). Heterocercal: top lobe is longer than bottom lobe.

5 SCALES Placoid scales Placoid scales Dermal denticles Dermal denticles (skin teeth) (skin teeth)

6 EXTRAS Spiracles: respiratory structures present in certain chondrichthyes located just behind the eyes. Water intake valves. Spiracles: respiratory structures present in certain chondrichthyes located just behind the eyes. Water intake valves. Spiral Valve: In stomach; increases surface area for absorption. Spiral Valve: In stomach; increases surface area for absorption. Squaline Oil: In liver; increases buoyancy. Squaline Oil: In liver; increases buoyancy.

7 MORE EXTRAS MORE EXTRAS Opportunistic feeder: Feeds when the opportunity arises. Obligate swimmer: Must swim in order to respire. Tonic immobility: Process by which shark becomes “paralyzed” by turning it over on it’s back (It appears to go to sleep). This is a temporary state!

8 SENSES (in the order that they detect prey) 1. Hearing: sound travels faster in water, attracted to low frequency sounds emitted by old, injured and /or dying fish 2. Smell: Blood trail (chum) stimulates sense of smell 3. Lateral line: feel vibrations from wounded prey

9 SENSES 4. Vision: can spot prey from 30 yards - nictitating membrane protects eyes. 5. Electroreception: (from Ampullae of Lorenzini) Jelly-filled sacs that detect electrical fields given off by all living things, open wounds, etc. --Can detect up to one millionth of a volt 6. Taste: upon contact with prey

10 REPRODUCTION Oviparous: Young hatch from egg laid outside the mother. Cat shark, Horn shark, Swell shark Viviparous: live born sharks. Each fertilized egg develops inside a separate compartment in the mother’s oviduct. Pup is feed via a placenta. Lemon, Blue, Bull, Hammerhead

11 REPRODUCTION Ovoviviparous: embryo develops in a large yolky egg kept inside the female’s oviduct. Embryos hatch while still inside the mother then develop more before being born. --Sand Tiger, Thresher display intrauterine cannibalism: where first pup to hatch in each uterus will eat its siblings. Claspers: Two fingerlike projections at the base of the pelvic fins in MALE sharks, (skates and rays).

12 4 Most Dangerous Sharks Great White Tiger Oceanic Whitetip Bull

13 SHARK ATTACKS Most shark attacks occur on sunny days in near shore waters 20  C or warmer. Most shark attacks occur on sunny days in near shore waters 20  C or warmer. Great White sharks prefer colder waters. Great White sharks prefer colder waters. Most common body parts attacked are the calves and knees. Most common body parts attacked are the calves and knees. Typically sharks will show an Agonistic Display before they attack: back is arched, pectoral fins are pointed down, and shark swims erratically. Typically sharks will show an Agonistic Display before they attack: back is arched, pectoral fins are pointed down, and shark swims erratically.

14 WILL YOU BE ATTACKED ? You have a better chance of being killed by a pig, bee, snake, elephant, plane or car crash. You have a better chance of being killed by a pig, bee, snake, elephant, plane or car crash. You have a better chance of winning the lottery. You have a better chance of winning the lottery. You have a better chance of getting struck by lightning twice in the same spot. You have a better chance of getting struck by lightning twice in the same spot.

15 THE HARD TRUTH Fisherman kill between million sharks / year. Fisherman kill between million sharks / year. Sharks kill between humans/year. Sharks kill between humans/year. That means that for every single human killed, there are 10 million sharks killed! That means that for every single human killed, there are 10 million sharks killed!

16 RAYS Identified by the presence of a barbed stinger on their tail. Identified by the presence of a barbed stinger on their tail. Swimmers can do the “Stingray Shuffle” to avoid getting stung. Swimmers can do the “Stingray Shuffle” to avoid getting stung. If a person gets stung, immerse the body part in hot water to denature (break down) the protein- based toxin. If a person gets stung, immerse the body part in hot water to denature (break down) the protein- based toxin.

17 Ray Migration Gulf of Mexico

18 SKATES Skates have a pointed “nose”, spots and thorns or spikes on their bodies, but no stinger. Skates have a pointed “nose”, spots and thorns or spikes on their bodies, but no stinger. Egg cases are called “Mermaid’s Purses” and are commonly found washed up on beaches. Egg cases are called “Mermaid’s Purses” and are commonly found washed up on beaches.

19 CHIMAERAS Often called Ratfish or Rabbitfish. Often called Ratfish or Rabbitfish. Have a venomous spine at the front of the first dorsal fin. Have a venomous spine at the front of the first dorsal fin. Males have a 5 th clasper on their head. Males have a 5 th clasper on their head.


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