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4 th 6-weeks Failures: : 1 st : 84.54%4 th : 86.05%7 th : 89.62% 100028564 (74) (83)**100022636 (67)100023579 (66) (87) 100023842 (70) (73)100011228 (63)***

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Presentation on theme: "4 th 6-weeks Failures: : 1 st : 84.54%4 th : 86.05%7 th : 89.62% 100028564 (74) (83)**100022636 (67)100023579 (66) (87) 100023842 (70) (73)100011228 (63)***"— Presentation transcript:

1 4 th 6-weeks Failures: : 1 st : 84.54%4 th : 86.05%7 th : 89.62% 100028564 (74) (83)**100022636 (67)100023579 (66) (87) 100023842 (70) (73)100011228 (63)*** 100022852 (68) 2 nd : 88.49%5 th : 84.02% 100038241 (73) (73)100023136 (I)* 3 rd : 87.90%

2 Bellwork: 03/01/2013 Collect the following data:  Salt Water Tanks Only:  - Phosphate  - Salinity  Nitrate- Calcium  Nitrite- Water Hardness  Ammonia  pH  Temperature Make sure to clean out any excess food from your filter and gravel/sand. Scrub off the inside of the glass & clean the outside with Windex once you are finished.

3 Feedback Questions: 1. What unit have you enjoyed the most & why? 2. What unit have you disliked the most & why? 3. Describe one aspect of my teaching style that you enjoy & explain. 4. Describe at least one aspect of my teaching style that you dislike/think needs improvement & explain. 5. Are there any units/subjects that could have used a lab or more labs that are reasonable ($$) to design? 6. A factor in teaching that is important to me is remaining relevant (relatable, non-authoritarian, someone you will listen to, etc) to my students. When I become irrelevant I intend to change jobs. In your opinion, what characteristics keep teachers relevant?

4 Bellwork: 02/28/2013 1.Hopefully that is the last time I’m gone 2.If you are still interested in the US-Australia water sustainability program that I mentioned last week please send an e-mail to: Subject line – US-Australia Virtual Environment Put your name in the body of the e-mail

5 Bellwork: 02/28/2013 1.AP Students: Make sure you have paid for your test, today is the last day to do so 2.March 4 th (Monday) – Late arrival for seniors

6 Bellwork: 02/21/2013 1) 1) List three differences between a ray and a skate: 2) 2) What is the purpose of a chondrichthyans’ oil-filled liver? This is similar to which organ found in bony fish?

7 Reminders for the Week: 1) 1) Friday is the end of the 6-weeks! 2) 2) Your cumulative (since August) is due on Friday. If you send the data to me earlier I can give you feedback & you can correct it. 3) 3) I will be out of town next Monday – Wednesday, so take care of your grades now.

8 Leadership Opportunity: 1) 1) I am in need of a team of 4 to 8 students to help with the following: 1) 1) Help develop an independent virtual model of our local water cycle with a keen eye on sustainable practices. 2) 2) This model will be connected with a school from Australia that is in a similar environment (Central Arid/Drought-Dominated) 1) 1)Centralian Senior College – Alice Springs, Northern Territory, Australia 3) 3) At the end of the project the models will be used as curriculum concerning Western water sustainability throughout the country 4) 4) Facilitate collaboration & communication across international boarders (USA, Bolivia, Australia) 2) 2) Project by the Department of Defense (DoD), Department of Cultural Exchange & Education (DCEE), and Global Connections & Exchange (GCE)

9 Lab Groups: 1) 1) No more than 4 per group 2) 2) You must move through the stations as a group. 3) 3) I will be monitoring who is helping & who is not.

10 Lab Safety: 1) 1) Wear gloves, goggles, and an apron when handling any of the persevered specimen. 2) 2) Keep in mind that some of the barbs on some of the organisms can still break your skin through the latex gloves. 3) 3) Handle the specimen carefully, they are easily damaged. 4) 4) Barb on Station #2, #3, #4 5) 5) If anything gets in your eye, or yet get cut, let me know immediately!

11 Bellwork: 02/19/2013  End of the 6-weeks is Friday  Cumulative Tank Data is due this Friday Make sure that all of the group member names are in your e-mail Make sure that all of the group member names are in your e-mail  Grades will close out on the following Friday (03/01/2013)  I will be in Annapolis, MD next Monday – Wednesday, so take care of your grades sooner rather than later 

12 Most-Missed Questions:   Which of the following is a result of reduced hybrid viability: a) a) Miscarriage of offspring b) b) Sterile offspring c) c) 2 nd generation unviability d) d) Speciation based of geographic barriers

13 Most-Missed Questions:   Which of the following is NOT a factor for genetic drift: a) a) It affects a large population b) b) Random chance changes the allelic frequency within a population c) c) It affects a small population d) d) The available alleles are limited in subsequent generations

14 Most-Missed Questions:   Which of the following situations describes stabilizing natural selection: a) a) Kudu are common prey for lions, and the fastest kudu in the group are more likely to survive an attack and pass on their genes. Thus, the population as a whole gets slightly faster with each generation. b) b) A population of gray mice is prey to nocturnal owls. The mice range in color from white to black, with most being gray. These gray mice are most likely to be spotted by the owls & over many generations the mice begin to split into separate species of white mice and black mice. c) c) Horses and zebra will often mate in the wild and produce a hybrid. These offspring are sterile, thus they can never create their own population. d) d) A population of hippo range in size from very small to very large. The smallest rarely pass on their genes due to their inferior stature, while the largest rarely make it to adulthood due to their high caloric demands. Thus, over many generations, the hippos within this population begin to resemble the average-sized hippos from the original population.

15 Most-Missed Questions:   All of the following are pre-zygotic reproductive barriers EXCEPT: a) a) Temporal isolation b) b) Mechanical barrier c) c) Habitat isolation d) d) Hybrid breakdown

16 Most-Missed Questions:   Which of the following geological times is defined by the global dominance of Homo sapiens (humans): a) a) Pleistocene b) b) Oligocene c) c) Pliocene d) d) Holocene

17 Most-Missed Questions: a) a) Which of the following graphs demonstrates stabilizing natural selection: a) a) c. a) a) d.

18 Most-Missed Questions:   A certain species of mouse is the prey of owls. These mice range in fur color from light to dark. For whatever reason, all of the mice except for the darkest are easily spotted by the owls. Over several generations, which type of natural selection would this population of mice undergo: a) a) Directional selection b) b) Diversifying selection c) c) Stabilizing selection d) d) Eliminating selection

19 Most-Missed Questions:   Consider a coral reef in the Atlantic Ocean: a species of clown fish are known to live all throughout this reef. During fishing season a large trawling net smashes the reef into three small pieces, all of which are separated by a large distance. After many generations the clown fish on the three different sections of reef become different species. This is an example of: a) a) Convergent speciation b) b) Parapatric speciation c) c) Sympatric speciation d) d) Allopatric speciation

20 Class Chondrichthyes: cartilaginous fishes  The class Chondrichthyes has two subclasses: Elasmobranchii, which includes the sharks and rays. Elasmobranchii, which includes the sharks and rays. Holocephali: the chimaeras: ratfish and ghostfish. Holocephali: the chimaeras: ratfish and ghostfish.

21 Class Chondrichthyes: cartilaginous fishes Elasmobranchii: Elasmobranchii:

22 Class Chondrichthyes: cartilaginous fishes Elasmobranchii: Elasmobranchii:

23 Class Chondrichthyes: cartilaginous fishes Elasmobranchii: Elasmobranchii:

24 Class Chondrichthyes: cartilaginous fishes Holocephali: Holocephali:

25 16.1

26 16.2

27 Class Chondrichthyes  Modern Chondricthyes include the sharks, rays, skates and Chimeras.  The Chondrichthyes’ well-developed jaws, highly developed sense organs, powerful swimming ability and streamlined shape (fusiform) have enabled them to thrive as marine predators for more than 350 million years, as other groups have come and gone.  There are just under 1000 living species, all of which have cartilaginous skeletons, even though they are descended from ancestors that had bone.

28 Class Chondrichthyes  The Chondrichthyes are an ancient group that although not as diverse as the bony fishes have persisted largely unchanged for hundreds of millions of years.  The oldest unambiguous Chondrichthyans are found in the Early Devonian although there are older fossils of scales.

29 Fossil history of Chondrichtyes  One of the best known extinct genera is Cladoselache (Greek for “branch-toothed shark”) a pelagic marine predator from the Devonian (416-360 mya).  It was shark-like in appearance. About 2 meters long with a large gape and three- pronged teeth. As in modern sharks the teeth were arranged on a ligamentous band in a whorl-shaped arrangement.

30 Fossil history of Chondrichtyes  Cladoselache:

31 Fossil history of Chondrichtyes  Cladoselache:

32 Fossil history of Chondrichtyes  Cladoselache had two dorsal fins, each preceded by a large spine.  It also possessed paired pelvic and pectoral fins as in modern sharks, but the fins were much more broad based than in later sharks.  The tail was symmetrical externally, but internally asymmetrical with the notochord extending into the upper lobe of the tail.

33 Cladoselache picture Cladoselache

34 Fossil history of Chondrichtyes  Cladoselache’s skin had few scales found on the fins and around the eyes.  In addition, Cladoselache lacked the rostrum of modern sharks.

35 Fossil history of Chondrichtyes  Rostrum:

36 Fossil history of Chondrichtyes  Rostrum:

37 Fossil history of Chondrichtyes  A contemporary genus of Cladoselache was Xenacanthus a freshwater shark.  A bottom dweller with robust fins and a heavily calcified skeleton.  Xenacanths appeared in the Devonian and died out in the Triassic (250-200 mya).

38 Xenacanthus

39 Fossil history of Chondrichtyes  Xenacanthus

40 Fossil history of Chondrichtyes  In the Carboniferous period (360-290 mya) sharks with modifications to feeding and locomotor structures arose.  An example is Hybodus of the late Triassic. It had heterodont dentition. Anterior teeth had sharp cusps for piercing and slashing softer foods. Posterior teeth were flattened presumably for crushing crustaceans and mollusks.

41 Fossil history of Chondrichtyes  Hybodus:

42 Hybodus

43 Fossil history of Chondrichtyes  Hybodus also had pelvic and pelagic fins supported by a narrow base made up of lengths of cartilage.  The narrow base (as in modern sharks) allowed the fin to be rotated.  Hybodus also had an anal fin and a true heterocercal tail.

44 Fossil history of Chondrichtyes  Heterocercal tail:

45 Fossil history of Chondrichtyes  Heterocercal tail:

46 Fossil history of Chondrichtyes  The elasmobranch heterocercal tail contains numerous radial skeletal elements which make it flexible.  Its shape can be controlled by intrinsic muscles.  When undulated from side to side the tail because of its shape generates both forward and upward thrust, which counteracts a shark’s natural tendency to sink.

47 Extant radiation of Chondrichthyes  By the Jurassic (200-146 mya) sharks of modern appearance had evolved. Several genera from that era are still extant.  The most distinctive feature of modern sharks is the rostrum or snout that overhangs the mouth.  Less prominent, but also of major importance was the evolution of solid calcified vertebrae.  Finally, the teeth are covered with thicker more complex enamel than in earlier sharks.

48 Megalodon  Megalodon (Carcharodon megalodon) is another extinct shark species that is the largest predatory shark known.  Megalodon occurred from 28-1.5 mya and at approximately16m long (and with a mass estimated at 47 metrics tonnes [103,617 lbs]) it resembled a massive great white shark and was the top ocean predator of its era.

49 “Megalodon (red), great white shark (green), and a human (blue) for scale. Note: The maximum size attained by C. megalodon is indicated by the 20 m scale.” From Wikipedia.great white sharkhuman





54 Megalodon  Megalodon preyed on anything it wanted including pinnipeds, sea turtles, and frequently whales.  Fossil whales skeletons contemporaneous with Megalodon show bite damage clearly inflicted by Megalodon.

55 Megalodon  Megalodon when attacking large prey is believed to have focused its attack on the rib cage area crushing the delicate organs within.  It also is believed to have bitten off appendages immobilizing the prey.

56 Megalodon  Megalodon’s bite force has been estimated at up to 10 times that of a great white shark and up to five times that of a Tyrannosaurus rex.  The large serrated teeth were deep rooted and Megalodon likely behaved like a great white which shakes its head after biting thus sawing through its prey.

57 Extinction of Megalodon  The formation of the Isthmus of Panama three mya resulted in large changes in ocean currents and reduced worldwide ocean temperatures.  Megalodon preferred warmer sea temperatures and the loss of warm water habitat coupled with a substantial decline in the diversity of whales (also as a result of changing ocean temperatures) is most likely the cause of the species extinction.

58 Thresher Shark Class Chondrichthyes

59  About 1000 living species divided into two distinct groups  Neoselachii [also known as elasmobranchs] (sharks, skates and rays) about 950 species.  Holocephalii (ratfishes). About 33 species.

60 Neoselachii  Neoselachii Galeomorpha: about 279 species of sharks with an anal fin. 1m to perhaps 18m in length. Sand tigers, mackerel sharks, threshers, basking sharks, hornsharks, whale sharks, nurse sharks, mako, great white. Galeomorpha: about 279 species of sharks with an anal fin. 1m to perhaps 18m in length. Sand tigers, mackerel sharks, threshers, basking sharks, hornsharks, whale sharks, nurse sharks, mako, great white. “Squalomorpha”: Not a monphyletic group. About 124 species of deep sea sharks, dogfish, angel sharks. 15cm to 7m. Batoidea: skates and rays. At least 534 species. Electric rays, Manta rays, stingrays, skates. 1-6m long and up to 6 m wide.

61 4 th 6-weeks Failures: : 1 st : 84.54%4 th : 86.05%7 th : 89.62% 100028564 (74) (83)**100022636 (67)100023579 (66) (87) 100023842 (70) (73)100011228 (63)*** 100022852 (68) 2 nd : 88.49%5 th : 84.02% 100038241 (73) (73)100023136 (I)* 3 rd : 87.90%

62 Bellwork: 03/05/2013 1. The Ampullae of Lorenzini are used to detect: 2. Name three distinguishing features of Chimeras:

63 Diversity of sharks

64 Hammerhead Shark

65 Great White Shark Skates Hammerhead sharks Whale shark

66 Skate (left) and ray (right)

67 Spotted Ratfish

68 Sharks  Sharks represent a little less than half of the elasmobranchs and most are specialized predators.  The largest species is the whale shark, which is a plankton feeder, as is the basking shark and the megamouth shark, but most of the others are predators of fish, marine mammals, crustaceans and whatever else they can catch.

69 Basking Shark Whale shark

70 Sharks  The extant sharks include at least two lineages and molecular studies suggest there may be several others included within these two.  The squaloid sharks are smaller brained, mostly live in cold, deep water and include the various species of dogfish, the megamouth, and cookie-cutter sharks.

71 Lesser spotted dogfish

72 Megamouth shark Cookie cutter sharks

73 Spiny dogfish

74 Sharks  The galeoid sharks are the dominant carnivores of shallow, warm species rich parts of the ocean.  They include hammerheads, tiger sharks, threshers, mackeral sharks, and the whale shark.

75 Sharks  Sharks are very well streamlined, but are heavier than water (because they lack a swim bladder) and sink if not swimming forward.  Sharks increase their buoyancy by having a large oil-filled liver that reduces their density, but not enough to prevent them from sinking.

76 Sharks  Sharks have an asymmetrical heterocercal tail and the vertebral column extends into the dorsal lobe.  The tail provides both lift and thrust, while the large flat pectoral fins also provide lift to keep the head up.

77 16.6

78 Shark skin  Unlike earlier sharks, living species have their skin entirely covered in dermal placoid scales, which are small tooth-like structures (with enamel, dentine and pulp just like real teeth).  These scales give sharkskin a tough, leathery and abrasive feel. The skin is also very streamlined.

79 16.15

80 Mako shark skin  The shortfin mako shark is capable of swimming in brief bursts at speeds approaching 50 mph (80.5 kph).  Recent research has shown that its skin is able to reduce drag by bristling, which creates tiny depressions across the surface of the skin (like those on a golf ball).

81 Shortfin mako Shark

82 Shark teeth  The placoid scales are modified in the mouth to produce the rows of replaceable teeth characteristic of sharks.  Each tooth in a shark can be rapidly replaced as it becomes worn or damaged. Teeth are not embedded in the jaw but arranged on a spiral or whorl shaped cartilaginous band in which replacement teeth are always developing behind the functional tooth.  Teeth in young sharks may be replaced as often as once every 8 days.

83 16.6





88 Variation in tooth structure  The type of teeth a shark possesses is dictated by the prey it eats.  Sharks that feed on crustaceans, mollusks and similar hard shelled prey have dense arrays of flattened teeth designed for crushing.  Fish feeders have long pointed needle-like teeth for gripping.



91 Porbeagle shark’s (a fish eater) teeth

92 Variation in tooth structure  Sharks that feed on large prey such as mammals have pointed lower teeth and triangular serrated upper teeth for cutting.  Plankton feeders such as basking sharks have small non functional teeth.


94 Blue shark upper (top) and lower jaws (bottom) /shark/english/teeth.htm

95 Shark Jaws  A shark’s jaws can open in a variety of different positions depending on the prey.  This is because the upper jaw is attached flexibly to the chondocranium in two locations (front and back) both of which can move. This is called a hyostylic (not directly attached to the jaw) jaw suspension.  Movement of parts of the head skeleton is called cranial kinesis.

96 Shark Jaws

97  The increase in volume is possible because the upper jaw attachment to the chondocramnium at the front is by elastic ligaments and so the upper jaw can move.  The increase in volume powerfully sucks water and food into the mouth.

98 Great White Shark

99 Shark Jaws  Protrusion of the upper jaw moves the mouth away from the head and allows a bigger bite to be taken than would be possible if the upper jaw was immobile.

100 Biting  The teeth on the upper jaw (palatoquadrate) have evolved to bite chunks from large prey items.  They are bigger than the teeth on the mandible and often curved and serrated, which enables the shark to saw off a big chunk of flesh.

101 Tiger Shark Teeth

102 Biting  When biting a large prey animal a shark seizes the animal sinking its upper and lower teeth into it.  The shark then protrudes its upper jaw which pushes its teeth deeper into the wound and violently shakes its head from side to side.

103 Biting  The head movements from side to side saw off a large chunk of flesh, which results in massive bleeding.  Great Whites kill big prey such as sea lions by taking a big bite and then waiting for the victim to bleed to death (exsanguination).

104 Prey detection  Vibrations can also be detected from a distance using the lateral line system.  Once a shark gets relatively close, vision takes over.  Sharks have very good vision at low light intensities. There is a high density of rods in the retina and a tapetum lucidum just behind the retina, which reflects light back through the retina.

105 Prey detection  In low light conditions the tapetum lucidum is beneficial, but in bright light is not.  In bright light melanin containing cells expand to cover the tapetum lucidum.

106 Prey detection  If a familiar prey item is located an attack may occur quickly.  If the prey is unfamiliar (e.g. a person) the shark may circle to gather more information.  Such a shark may bump the potential prey with its rostrum presumably to gather extra sensory information.

107 Shark attacks on humans  1990’s 514 documented unprovoked shark attacks on humans. About 13% fatal.  In a typical year there are 3-4 fatalities worldwide.  In U.S. most shark attacks are in Florida.

108 Shark attacks on humans  Great White, Tiger and Bull sharks are the big three for shark attacks.  International shark attack file statistics (documented attacks1580-2007) White 237 attacks 64 fatalities White 237 attacks 64 fatalities Tiger 88 attacks 28 fatalities Tiger 88 attacks 28 fatalities Bull 77 attacks 23 fatalities Bull 77 attacks 23 fatalities

109 Bull shark

110 Foraging strategies of sharks  Various sharks employ different strategies to obtain prey.

111 Great White Shark  Great White sharks specialize in feeding on colonial seals and sealions, but also take a wide variety of other prey including dolphins, other sharks, turtles and other fish.  Around sea lion nursery areas sharks attack the mammals as they come and go. They remain deep in the water until a victim passes within range above and then rocket to the surface like a trout after a mayfly often exploding out of the water and flinging the prey in the air.

112 Great White





117 Great White Shark  Great Whites appear to be relatively intelligent and there are reports of them cooperating to attack a seal.  There are also reports that they are very curious and they will often raise their head out of the water to look something over.

118 Great White Shark  A lot of attacks on humans by Great Whites are likely cases of mistaken identity as a surfer on a surfboard looks a lot like a sea lion.  Frequently people bitten by a Great White are released. Humans (and sea otters) lack of blubber results in them often being released after an initial bite.

119 Shortfin mako  The shortfin Mako shark specializes in attacking fast moving prey such as bluefish, mackerel, bonito, swordfish, sailfish as well as dolphins and porpoises.  A study of mako stomach contents of sharks taken off of the eastern U.S. found that bluefish made up about 77% of the diet by volume.

120 Shortfin mako  Because it hunts such fast prey, makos have to be fast and athletic. Its speed has been recorded at 50km/h (31 mph), but in bursts it can accelerate to 74 km/h (46 mph).  Makos often leap high out of the water in pursuit of prey and there have been several instances of hooked makos landing on the decks of fishing boats.

121 Shortfin mako



124 Thresher Shark  A Thresher shark is instantly identifiable thanks to the enormously elongated upper lobes of its tailfin. Thresher shark Thresher shark  The tail plays a central role in their hunting strategy. Either working alone or in groups threshers surround groups of pelagic fish and stun or disorient them using their tails.



127 Tiger shark  Tiger sharks are indiscriminate consumers and will eat almost anything.  Their powerful jaws allow them to crack turtles shells and clams.  Stomach contents of captured sharks have included humans, seals, sea snakes, birds, fish, squid and even old tires.

128 Tiger shark  Tiger sharks trail only great whites in numbers of attacks on people, but because they will eat almsot anything they rarely leave after biting a human, as great whites often do.

129 Tiger shark


131 Cookiecutter shark  Cookiecutter are bizarrely specialized predators that bite disk-shaped pieces of tissue out of much larger animals.   Cookiecutter sharks attach to their prey with their lips and then quickly spin using their proportionally enormous teeth to carve out a piece of flesh.  Cookiecutter sharks feed on megamouth, basking and whale sharks as well as fish such as tuna and marlin as well as dolphins and whales.

132 Cookiecutter shark  Cookiecutters are bioluminescent and appear to use this ability to attract victims.  On the ventral surface cookiecutter’s glow along their whole length except for a dark patch of skin under the jaw.  The bioluminescent areas hide the shark against the light of the surface water, but the dark patch stands out and acts as a lure for predatory fish, which when they attack end up being bitten by the shark.



135 Whale Shark  Whale sharks are filter feeder that sieve plankton, krill and other small prey from the water.  The prey is trapped using 10-cm long gill rakers, which are bristle-like structures that sieve the water before it passes through the gill slits.  Whale sharks filter about 1500 gallons (6000 liters) of water each hour. Basking sharks and megamouth sharks also filter feed.


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