chapter 10 sharks skates and rays

Chapter 10

Vertebrates• Everything up till now has been Invertebrates– What does this mean?

• From now on all Fishes, reptiles, birds and mammals are all Vertebrates– What does this mean?

• Can you think of some functions of Vertebrae that are advantageous?– Support– Attachment of muscles= increased movement

Primitive Fish

• Class Myxini (hagfish) and Cephalospidomorphi (lampreys)– Lack jaws and paired appendages (fins in fish)– Lack scales and muscles (all cartilage) Only living representatives of primitive fish

Class Chondrichthyes

• Sharks, Skates, and Rays– Defining characteristics• Skeletons composed of cartilage • Jaws• Paired fins• Placoid scales

Sharks!!!!!• Streamlined body shape• Heterocercal tail• Two dorsal fins• Paired pectoral fins• Paired pelvic fins– Modified in males (claspers) to transfer sperm

Why do sharks have to “just keep swimming”?

• Has to do with Density!!!!– The are denser than the water so what will

happen if they stop swimming?

Osmoregulation

• Maintain homeostasis– By holding large amounts of urea in body– If they did not have this adaptation they would

lose body water.• Then what would happen to the shark

– Dehydrate and cells would……… » Shrink -> remember osmosis chapter?????

– http://dsc.discovery.com/videos/the-ultimate-guide-to-sharks-how-sharks-swim.html

Sensory in Sharks

• Sight– Lack eyelids– Scientists predict that they can see color, but what

sense is most dominant in shark?• Smell!!!!– 2/3 of cells in brain are used to process sense of

smell– Can detect 1 drop of blood in 1 million parts of water– http://dsc.discovery.com/videos/ultimate-guide-the-

sharks-shark-smell.html

• Lateral Line System– Canals that run length of

body and open up to surrounding H2O

– Used to detect movements in water• Locate prey and predators

– Ampullae of Lorezini• Organs around head (what is

the term for sense organs near the head?)– Sense electrical

– http://dsc.discovery.com/videos/ultimate-guide-the-sharks-vibrations-and-shark-vision.html

Digestion

• Teeth– Several rows of teeth– Fall out and are continually

replaced throughout life• Not like ours where we only

get two sets

– Shake head to bite b/c they cant move jaws up and down to chew

– Food is swallowed whole– Mouth ->stomach-> small

intestine

Great White Jumping!!!

• http://dsc.discovery.com/videos/planet-earth-pole-to-pole-great-white-hunt.html

Reproduction

• Sexual, separate sexes• Fertilization is internal

– Males transfer sperm via claspers

– Females have ovaries and oviduct (modified uterus)

– http://dsc.discovery.com/videos/ultimate-guide-the-sharks-shark-mating.html

3 types of Reproductive types

– Oviparity (most primitive)• Eggs are laid outside body• Develop in protective case that attaches to seafloor• smaller b/c limited nutrients• Whale sharks, bullhead sharks

– Ovoviviparity (most common)• Eggs hatch in mothers uterus• No placenta, nourishment is yolk stored in egg• Single pup

– Viviparity (most recent, advanced)• Babies get milk directly from mother• Hammerhead shark

Skates and Rays characteristics

What animal from previous chapter do they resemble?

• Flattened bodies shape– Suited for bottom living

• Always exception = manta ray

– Enlarged pectoral fins attached to head

– Reduced dorsal and caudal fins

– Eyes and spiracles on top of head

– Lack of anal fin– Specialized teeth for

crushing prey

Differences between skates and rays

• Skates– Small fins on tail– Swim by creating a wave

and starts at head then ripples down rest of body

– Oviparous - “mermaids purse”

• Rays– Venomous barb or

spines– Swim by moving fins up

and down (like a bird)– Ovoviviparous

• http://dsc.discovery.com/videos/ultimate-guide-the-sharks-shark-mating.html