Marine Fishes Ch.7
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Transcript of Marine Fishes Ch.7
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Marine FishesCh.7
Part 1: Jawless & Cartilaginous Fishes
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Objectives
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Vertebrates
• What defines a vertebrate?– Backbone or spine– Spinal cord
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Jawless Fishes
• Most primitive• Feed by suction
– round, muscular mouth– Rows of teeth
• Elongated, cylindrical body (like snake)
• No paired fins or scales
Lampreys
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Hagfishes
• aka: slime eels• No eyes• Feed on dead or dying
fishes• Ca bore into prey and
eat from the inside out• Pours slime out of
mucus sacs– Can fill a 2 gallon bucket
instantly!– Don’t believe me?
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Hagfish• Deep sea environment (1000
ft)• Been around 300 million
years• No eyes—virtually blind• Highly acute sense of smell
and touch• Smooth body helps it move
around inside dead animal• Eat prey from the inside out• Slime
– used as defense mechanism– Protein explodes when in water
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Hagfish and Whale• Over 5,000 feet deep!• Over ½ meter long• Breathe in gill openings
on sides of body• Eats several times its
own weight in rotting flesh
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Bonus Feature: Fear Factor
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Lampreys
• Primarily freshwater• Breed in rivers and
lakes, move to sea as adults
• Attach to fishes and suck blood
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Lampreys as food?
Haggis: The national dish of Scotland. It is a sheep’s heart, lungs and liver minced up with oatmeal and cooked in the lining of the stomach for three hours. Yum.
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Cartilaginous Fishes
• Sharks, rays, skates, and ratfishes
• Skeleton of cartilage– Lighter, more flexy than
bone
• Paired lateral fins for swimming
Tiger Shark
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Cartilaginous Fishes
• Movable jaws and teeth• Mouth is ventral
– Underneath the head
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Cartilaginous Fish
• Placoid Scales– Rough, sandpaper like– Pointed tip that points
backward
• produces a covering that offers low resistance and turbidity
• copied in the body suits of Olympic swimmers.
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Sharks“The Heavyweight Champs of Evolution”
• Read excerpt from The Devil’s Teeth (last paragraph, page 5).
• Been around over 100 million years
• The Frilled Shark – a living fossil
• Let’s watch a movie: American Shark
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The Perfect Predator
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The Perfect Predator: Body Shape
• Torpedo shape– Body tapers at each end
• Well developed, powerful caudal fin
• Arching the body laterally into a shallow curve– Tremendous speed, low
energy useageMako Shark
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The Perfect Predator: Coloration
• Dark on dorsal (top) side
• Light on ventral (bottom) side
• Why?• White blends with light,
dark blends with bottom
The Great White Shark
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The Perfect Predator: Teeth
• Up to hundreds of teeth in jaw at one time
• Embedded in flesh– Not attached to jaw
• Multiple rows• Serrated• Replaced when lost –
for entire life!
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Tiger Shark and it’s Teeth
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The Perfect Predator: Eyes
• Extremely sensitive– Able to magnify amount
of light
• Rolls eyes backwards when attacking– Exposes tough, fibrous
coat
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The Perfect Predator: Nostrils• ONLY used for smell• Skin flaps
– Inflowing/outflowing current
– Water passes over lamellae
• Lamellae– Covered with millions of
sensory cells– Single drop of blood in an
Olympic size pool
• Smell is directional– Can tell where it’s coming
from
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The Perfect Predator: Ampullae of Lorenzini
• Thousands of small capsules filled with jelly
• Picks up vibrations in water of prey
• Detects electrical fields of moving animals
• Detects magnetic field of earth– Used in migration
• More detail
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Let’s watch some hunting
• Planet Earth’s “Shallow Seas” video clip
• Ch. 4, 36 minutes in• Ch. 6, 48:30, Diaries
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Other Sharks: Whale Shark• Largest shark (and fish) in ocean
– 65ft, 10+ tons
• Filter feeders– Fish eggs– Plankton– Krill– Small fish and squid
• Process over 6000 gallons of water/hr
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Other Sharks: Hammerhead• Sensory mechanisms all along flattened scull• Head acts as airplane wing• Can detect a billionth of a volt• Excellent 3-D eyesight• Excellent navigation
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Let’s watch “Air Jaws,” a movie on my favorite shark: Great Whites
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Importance of sharks• Meat
– Nutritional, boneless, mild-flavoring
• Eyes– Corneas used as
substitutions for human corneas
• Skin– Used in research and
engineering of ships, aircraft, pipelines and swimming suits
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Importance of sharks• Liver
– Contain high amounts of vitamin A (helps us see)
– Squaline• Skin rejuvenator
• Cartilage– Cancer research
• Ecosystem– Apex predators– Control disease– Quick article
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As Sharks Vanish, Chaotic New Order Emerges
• What are some impacts that have resulted in the overfishing in sharks on the east coast of the US?
• In your own words, what is an “apex predator?”
• What is an example of a “trophic cascade?”
• What is shark “finning?” What are some problems with it? “This is how we do it in Oklahoma,
boy.”
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Sharks are in great decline• Overfishing• K-selected species
– Low fecundity• Do not produce many young
– Reproduce every two years– Slow growth– Late age of maturation
• Great White: 9 years; Sandbar: 25 years
• Cartilage:– It cures cancer! NO IT DOESN’T! No
evidence!– $100 million-a-year industry– Read page 23 in thesis, 2nd paragraph
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Sharks are in great decline
• Bycatch– Occurs in several
fisheries: tuna longline, shrimp trawl, and swordfish
– Millions of sharks a year
• Finning– Removing the fins and
discarding the carcass– This makes me sick to
my stomach…
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Shark Finning
Play up until turtles
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Shark Fin Soup
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Sharks in Deep Trouble
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Why can’t we all just be friends?How to Hug a Shark
Don’t try this at home
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Rays
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Characteristics
• Adapted to living on bottom of ocean
• Flattened bodies• Gill slits (5 pairs) on
underside of body• Feed on clams, crabs,
small fishes
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Stingrays• Lie camouflaged in
sand• Finds food by smell,
touch and electrical senses
• Up to 6 ft across• Spine found at base
of tale laced with poison– Use in defense only
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A closer look at the tail
• This is a bull ray– Same type of ray that
killed Steve Irwin
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Manta Rays• Largest of all rays• Up to 22 feet across (average size is 12 ft)
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A New Species of Manta Ray
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Electric Ray
• Organs on side of head that produce electricity
• Shocks up to 200 volts– Used to stun prey
• Used by Romans to cure treat headaches and other ailments
• Confrontational if harassed.– Swim directly up to diver
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Skates vs. Rays• Rays live bearing (viviporous)• Skates are egg bearing (oviporous)• Rays have longer, skinnier tale with spine• Skates have fleshier tale, no spine• Rays have plate like teeth• Skates have small teeth• Which is which?