1. Class: Chondrichthyes - Sharks, Skates and Rays

2. Class Chondrichthyes cartilagenous fishes :
rays, skates, sharks, and ratfishes
Distinguishing Characteristics
cartilage skeleton w/Ca2+ granules
Placoid scales also known as Denticles
Big Phylum advance –
paired fins
movable jaws
well developed teeth

3. Advances
PAIRED FINS
Moveable Jaws
Well Developed Teeth

4. External Covering All have placoid scales
Rays – few rows on back; sometimes modified into spines
Sharks – skin overlapping into lightweight, protective coat
fast-swimming sharks have channels between scales to minimize turbulence

5. Placoid scales of sharks
These fishes have teeth-like scales called denticles.
They are similar in structure to teeth and cause the skin to be very abrasive if rubbed in the wrong direction.

6. Class: Chondrichthyes - Sharks and Rays
The shark’s skeleton is entirely composed of cartilage.
Most have gray, brown, white or black coloring; are not camouflaged but may be counter-shaded.
Also have ventral mouth (underneath)
Only predators are toothed whales and man. Puffer fish can accidentally suffocate a shark by blocking water from entering the gills resulting in death for both.

7. Countershading
Ventral Side is lighter to blend in with the sea surface when below the shark
Dorsal Side is darker to blend into the substrate when above the Shark

8. Shark’s tooth like scales are called
Denticles
Toothskin
Armoricles

9. Darker Dorsal coloring and lighter ventral coloring is known as
Camouflage
Two tone shading
Counter Shading
Bioluminescence

10. Shark cartilage has not been proven to prevent cancer, and sharks with tumors have been observed.
Circulation: 2 chambered heart; cold-blooded
Respiration: Gills are located in muscular slits behind the mouth. They exchange oxygen from the water into the blood.
Sharks lack swim bladders and must constantly swim upwards to balance their weight. They do sleep.

11. Respiration 3 basic means of respiration
1) Two-pump system (like teleosts) – pump O2 water across gills in slow-moving, bottom oriented sharks
2) Ram ventilation – push water across gills during swimming; fast-moving sharks
3) Spiracles – used to bring water across gills; small round opening precede gills on lateral sides of head – on top of head in rays – almost absent in pelagic sharks

12. Spiracle allows the shark to take in water even when their ventral mouth is buried in the sand

13. Senses: Vision is good in clear water
Senses: Vision is good in clear water. Eyelids close from the bottom upwards to prevent injury during an attack. Nictitating Membrane protects the eye when the shark attacks its prey
Smell is excellent. Olfactory lobes compose 2/3 of the brain. Sharks can detect a drop of blood 1/4 mile away in the water and can determine the direction of the source.
Hearing is excellent. Sound vibrations can be detected by the lateral line from 3,000 feet away. Esp low frequency hearing
The electrical impulses of breathing from a prey can be picked up through pores in the face in structures called Ampullae of Lorenzini.

14. Sharks have a _____ chambered heart1 2 3 4

15. Two thirds of the shark brain is devoted to the sense of
Sight
Motion
Smell
Hearing

16. The whale shark is over
50 feet long. It is a filter-feeder with baleen instead of teeth.
Largest shark
Great White sharks are found in the temperate and tropical oceans worldwide.

17. Which two Sharks are filter feeders
Whale Shark and Basking Shark
Tiger Shark and Bull Shark
Lemon Shark and Whale Shark
Basking Shark and Nurse Shark

18. Vertebrate jaws evolved from skeletal supports of the pharyngeal slits

19. Sharks have a ________ mouth
Dorsal
Lateral
Ventral
Anterior

20. Predation: Efficient, top carnivore of the sick, weak, old and injured
Predation: Efficient, top carnivore of the sick, weak, old and injured. Sharks will not eat Moses sole.
Jaw is lined with rows of teeth like a conveyor belt. Teeth can be replaced every 24 hours and are used to identify species.
Jaw can be extended out of the mouth for extra reach.
There are over 370 species of Sharks known to man.
Mote Marine Laboratory in Sarasota, FL is a leading research center in shark immunology.

21. Replaceable teeth

22. Sharks have amphistylic suspension of jaw
Upper jaw not fused to chondrocranium – only by a couple of ligaments
Whips upper jaw down into prey. Drives Jaw deeper into the victim.

24. Teeth can be replaced every ______ hours12 48 24 6

25. Be able to identify the fin and Clasper Locations !!!!

26. Shark Parts Pectoral fins – provide lift
Dorsal, anal, pelvic fins – rudders/skegs
Heterocercal caudal fin – lift, propulsion
Claspers – modified part of pelvic fin on males for mating

27. Fixed Pectoral Fins

28. Reproduction Reproduction is internal Cartilaginous fish are either
Ovoviparous – meaning the female retains the eggs within her body. The embryo gets nutrition from yolk of egg. OR
Vivapous- live bearers. Embryo gets the nutrition directly from the mother.

29. Reproduction
Osmoregulatory and and reproductive systems likely evolved simultaneously;
Long gestation periods of embryos (in egg or ♀, would not be possible without ability to withstand high concentrations of waste

30. Reproduction
Unlike most bony fishes (teleosts) put most energy into relatively small number of large, active, young (ecological term?)
Wide variety of means to this end:
egg laying (oviparity) to live bearing (viviparity); all stages inbetween

31. Horn Shark

32. Horn Shark Egg Case

33. Claspers modified fin for reproduction

34. Reproduction: sexual, internal fertilization
Reproduction: sexual, internal fertilization. Most sharks have live births - dogfish have 4-10 pups, tiger sharks may have at one time. A few species lay eggs.

35. Shark Structures Reflect Predatory Lifestyle
Teeth – on replaceable “roll”
Nares – for smelling + huge olfactory bulbs
Ampullae of Lorenzini – sense electrical fields
Lateral Line system – senses water vibrations (bony fish also have)
Good vision (but not color)
Reasonable hearing – esp low freq.

36. Ampullae of Lorenzini

37. Ampullae of Lorenzini

38. Nictitating Membrane & Ampullae of Lorenzini

39. Lateral Line (shown on bony fish, but sharks also have it)
Used to sense movement

40. Lateral
Line

41. Some Sharks are Plankton Eaters
Whale shark (largest fish)
Basking shark (sea monster stories)
Megamouth shark

42. Basking Shark Gill Rakers

43. Whale Shark

44. Megamouth Shark

45. Megamouth Shark

46. Basking Shark

47. Odd Shark Body adaptations
Thresher Shark elongated caudal fin
“Hammer” for lift, separates eyes and nares, may bash prey

48. Goblin Shark
Deep water shark found off of the coast of Japan. Can grow to up to 14ft long.
Little is known of this Shark.

49. Buoyancy -no swimbladder -combination of methods to reduce density
Cartilage less dense than bone (1.1 vs 2.0)
Large, oil-filled liver (0.8) (water 1.0)
Hydrodynamic lift from heterocercal tail & pectoral fins

50. External Covering Slow-moving sharks more “armored” - dorsal spines
Rays – barb/sting
Skates – denticles
Teeth are modified placoid scales

51. Feeding Most are specialized predators – teeth dictate type of feeding
Triangular, blade-like teeth – large fish & marine mammals
Long, thin, pointed – whole fish
Rows of small, sharp teeth – small inverts
Flattened, pavement-like teeth – hard-shelled inverts
Pointed in front/flattened in back – small inverts (grasping and crushing)

52. Shark Feeding
Teeth continually shed & replaced; may loose 30,000 in lifetime
Jaws loosely attached to cranium - can throw jaws or create suction
Large stomach & spiral valve intestine

53. Movement Large heterocercal tail
Counter-current heat exchangers in pelagic sharks (Lamnidae)
Pectoral fins (Mylobatidae) – fly through the water

54. Movement
Homocercal
Heterocercal

55. Sensory Systems
Odor – olfaction detects dissolved chemicals in the water
Low frequency sounds – inner ear and lateral line system; “hear” and “feel” sound waves respectively
Ampullae of Lorenzini – pit organs filled with an electrically conductive gel used for detecting weak electrical currents & magnetic fields

56. Osmoregulation
Osmoregulators – regulate internal salt concentration approximately 1/3 seawater
Utilize large quantities or organic salts (urea & trimethylene oxide)
Invade marine, estuarine (brackish) and freshwater systems

57. CHORDATA Subphylum Vertebrata
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display
CHORDATA Subphylum Vertebrata
White-tip reef shark (Triaenodon obesus), Fiji
Indo-Pacific and east Pacific, common on reefs resting under plate corals
Photo Copyright © Diane R. Nelson

58. CHORDATA Subphylum Vertebrata
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display
CHORDATA Subphylum Vertebrata
Gray reef shark (Carcharhinus amblyrhynchos), Blue Corner, Palau
Numerous on reefs in Indo-Pacific
Often in groups to hunt fishes
Photo Copyright © Diane R. Nelson

59. Shark attacks on humans are rare, but with more people in the water the odds are increased.
Sharks may be looking for new food sources due to over fishing.
Most attacks occur in less than 6 feet of water, at dawn or dusk, during summer months. Risks are also increased for surfers and swimmers in water with reduced visibility.
A surfer in black wet-suit, paddling out on a board, may look enough like a seal to interest a shark.

60. Most attacks occur in Florida, California, Australia, and Africa
Most attacks occur in Florida, California, Australia, and Africa. Florida has 4 times
the number reported in California. Most attacks are not fatal.
Sharks only kill about 10 people worldwide per year. Bees kill hundreds of people and crocodile/alligator - related deaths number nearly 1000.
People have done far greater damage to the shark population.

61. Shark Attack

62. Shark Attack

63. Most Shark attacks occurs during
The Night
Noon
Dusk and Dawn
The Evening

64. The two states where shark attacks occur most frequently are
Hawaii and California
Florida and Australia
Africa and Florida
California and Florida

65. Sharks kill about ______ people per year
1000
100 10

66. S-U-C-C-E-S-S Success due to adaptive characteristics: 1) buoyancy
2) respiration
3) external covering
4) feeding
5) movement
6) sensory systems
7) osmoregulation
8) reproduction

67. SKATES AND RAYS

68. Rays and Skates Same subclass as sharks
Most are Demersal – hover along the sea floor
Distinguishing characteristics
flattened bodies, pectoral fins modified to “flap”
gill slits and mouth on ventral surface, eyes are dorsal

69. Rays Distinguishing Characteristics Viviparous – Live births
Flat, platelike teeth –used to crush crustaceans
Streamlined tails, maybe barbs or spines

70. Pteroplatytrygon violacea
Order Mylobatiformes
Family Platyrhinidae – (thornback ray)
Family Zanobatidae – (pan rays)
Family Hexatrygonidae – (longsnout stingray)
Family Urolophidae – (round rays)
Family Urotrygonidae – (smalleyed round ray)
Family Dasyatidae – (stingrays)
Family Potamotrygonidae – (river rays)
Family Gymnuridae – (butterfly rays)
Family Myliobatidae – (eagle rays)
Spotted eagle ray
Aetobatus narinari
Pelagic stingray
Pteroplatytrygon violacea        

71. Manta Rays may have a 25 foot wide wing span.
Largest ray
Manta Rays may have a 25 foot wide wing span.
Video: Manta Rays in the Maldives
Sting Rays have a venomous stinger in their tail. Shuffle your feet when wading to avoid stepping on it.
Stingrays are generally docile and will swim close to divers and snorkelers without fear

72. Stingray injury
Injuries usually come from an unsuspecting person stepping on a stingray
Reflexive action by the stingray
Usually lower legs
Painful due to Protein based toxin in barb

73. Long spiny tail
Dorsal eyes
Flattened body
Perfect for demersal living
Modified pectoral fins used for flapping

74. The population in the Gulf of Mexico migrates, in schools of as many as 10,000, clockwise from western Florida to the Yucatan. .
Golden Rays also known as Cow nose rays

75. Manta Rays
(plankton eaters)

76. CHORDATA Subphylum Vertebrata
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display
CHORDATA Subphylum Vertebrata
Southern stingray (Dasystis americana), Bahamas
Venomous spine at base of whip-like tail
Often lie on bottom in sandy areas
Photo Copyright © Diane R. Nelson

77. Skates Distinguishing Characteristics Oviparous (lay egg cases)
Cusped teeth – Carnivorous mainly benthic organisms
Fleshy tail w/ small fins
Barndoor skate
Great Camouflage!

78. Skate Egg Case Sometimes known as “Mermaid’s purses”
Common on the beaches here in the NE

79. Skate
Note: The fleshly tail

80. Ratfishes Different subclass from sharks (Subclass Holocephali)
deep-water cartilagenous fishes
“chimeras”
demersal, feed on benthic inverts
Distinguishing Characteristics
Gill slits covered by a flap of skin

82. Adaptations for Other Lifestyles
Deep water shark
Cookiecutter
Shark

83. Websites Who's Who of Sharks Video shark attack survival tips
USS Indianapolis CA-35