Transcript Chapter 16

Chapter 16
Marine Animals - Vertebrates
Phylum Chordata
 All members of the phylum (the most advanced of the
animal phylum) have a stiffening notochord.
 Notochords are stiff rods of connective tissue.
 The also have a tubular dorsal nervous system and gill
slits behind the oral opening at sometime during their
development.
 The notochord serves as a rigid support and a
foundation for muscles and bone.
 5% of 45,000 species of chordates lose their notochord
as they develop.
 These are invertebrate chordates.
 95% retain the notochord or the vertebral column that
forms around it.
 These are called Vertebrate Chordates.
Classification of Groups
Within the Phylum Chordata
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Phylum Chordata
Subphylum Urochordata – Tunicates
Subphylum Cephalochordata – Amphioxus
Subphylum Vertebrata:
Class Agnatha (jawless fish) – Hagfish; lamprey
Class Chondrichthyes (cartilage skeleton) – Sharks;
Rays; Skates
 Class Osteichthyes (bony skeleton) – tuna; seahorse;
puffers
 Class Amphibia – frogs; salamanders
 Class Reptilia – crocodiles; turtles; snakes
 Class Aves – gulls; penguins; terns
 Class Mammalia – Whales; seals
 Fishes
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Vertebrates that usually:
Live in water
Possess gills
Have fins
 There are more species of fish and more
individuals than species and individuals of all other
vertebrates combined.
 Fish range in size form 10 millimeters to over 20
meters (.4 inches to 60 feet)
 Fish weigh from 0.1 gram to 41,000 kilograms. (.004
ounces to 45 tons)
 Fish are Ectotherms – cold blooded – can not maintain
a steady internal temperature.
 40% of species live all or part of their life in freshwater.
 60% live exclusively in salt water.
Class Agnatha
 (a = lacking; gnathos = jaw)
 Examples – Hagfish and Lampreys
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Lack jaws
No paired appendages
Have gill slits
Have openings to slime glands
Have round sucking mouths surrounded by organs sensitive to
touch
 Tails are flattened
 Eye are covered by thick skin
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Hagfish:
Pink
Live in colonies
Feed on the inner tissues and internal organs of its
prey
 Lamprey;
 Have a toothed, funnel-shaped mouth
 Rasps through scales and skin to get nutrients from
blood
Class Chondrichthyes
 (chondros = cartilage; ichthys = fish)
 The skeleton is made of cartilage. Some calcification
is present, but true bones do not exists.
 They have jaws with teeth
 They have paired fins
 Sharks and Rays tend to be larger than either
Agnathans or bony fish.
 Only a small fraction of all fish species are members of
this group.
 Nearly all are marine; a few species will inhabit
estuaries and very few are found in fresh water.
 Skates and Rays have flattened bodies with spreading
pectoral fins – They move by flapping of thes fins.
 Neither sharks or rays have gas bladders and both are
slightly negatively buoyant; they sink if they stop
swimming.
 Rays have smooth skin
 Sharks are covered with a tooth-like placoid scale.
 Rays:
 Some have a defensive barb
on their tail
 Some grow to 7 meters
across (giant Manta)
 Some have the ability to
shock their prey.
 Sharks:
 80% are less than 2 meters
long
 Not very intelligent
 Hunt prey by vibrations in the
water and also by smell.
 Largest – Whale shark; 18 meters (60 feet), 41,000
kilograms (90,000 pounds); feed on plankton
 Carcharodon (Karcharos = sharp; odontos = tooth)
Great White Shark; 7 meters, 1,400 kilograms
 Other “dangerous” species: Mako; Tiger; Hammer head
Class Osteichthyes
 (osteum = bone; ichthys = fish)
 27,000 + species of bony fish
 Success due to light, hard, strong skeleton that
supports them.
 Most numbers and successful of all vertebrates.
 Representatives of this class are found in every marine
habitat.
 90% of all fish belong to the Xlass Osteichthyes and
the Order Teleostei (teleos = perfedt; osteon = bone)
 This group contains the most familiar of the fish; perch,
tuna, flounder,etc.
 They have a gas filled swim bladder to help maintain
neutral buoyancy.
 They have independently movable fins for well
controlled swimming.
 The are capable of great speed for pursuit or
avoidance of predators.
 They have effective camouflage.
 They have social organization
 They have an orderly pattern
of migration.
 They have the ability to
cluster together in defensive
schools.
 Over 77 million tons of
bony fish are taken
annually form the ocean for
consumption.
Movement, Shape &
Propulsion
 A fish’s resistance to movement (drag) is determined
by the frontal area, body contour and surface drag.
 Drag increases geometrically with increasing speed.
Faster swimming fish must be highly modified to
minimize drag.
 The most effective antidrag shape is a tapering
torpedo-like body plan.
 This shape produces
minimum drag when they are:
 A. circular in cross-section
 B. greatest width is ¼ the
length
 C. the point of max width
occurs about 2/5 the
distance from the leading
tip
 Thrust come from a combines effort of the body and
fins.
 Muscles in slender flexible fish (eels) create S-shaped
waves along the body. The body pushes against the
water.
 This movement is not efficient; body length to width
ratio must be too high (this increases the surface area
that creates drag)
 More efficient forms have shorter less flexible bodies
that undulate more rapidly and a hinged tail to transfer
muscular energy to the water.
 How Efficient?
 In the fastest fish 60-80% of
muscle force delivered to the
tail results in forward
movement.
 Marlin & swordfish can travel
33 meters/second (75 mph)
Maintenance of Level
 The density of a fish’s tissue is greater than
surrounding water.
 This difference is offset by propulsive forces and by
buoyant gas or fat-filled bladders (swim bladder)
 The quantity of gas is controlled by:
 A. secretion and absorption of gas from the blood
 B. muscular contraction of the bladder.
 Fast predators lack a swim
bladder. The volume would
have to change too rapidly
and the chance of rupture is
great.
Osmosis
 (Random movement of water molecules from areas of
greater concentration to areas of lesser concentration
across a semi-permeable membrane)
 Primitive vertebrates and marine invertebrates have an
internal salt content almost identical to sea water.
 Advanced vertebrates tissue contains fluid ½ as saline
as sea water. They are Hypotonic to their
surroundings.
 The cells of marine fish contain a lower concentration
of solutes (salts) than its surroundings.
 Because of this fact, water is lost constantly to the
environment, by osmosis
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Ton control the loss of water from the body marine fish:
A. make smaller amounts of urine
B. actively drink water
C. eliminate excess salts through special salt secreting
cells in the gills
 The process of adjusting internal salt concentration is
call Osmoregulation.
Marine Reptiles
 Each of the 3 main groups within the Class Reptilia have marine
representatives:
 A. turtles
 B. sea snakes
 C. marine lizards
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Each of these groups:
1. are ectothermic
2. breathe air using lungs
3. are covered with scales and an impermeable skin
4. have salt glands that concentrate and excrete salt
Marine Turtles
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Most successful living marine reptile
8 Species
More streamlined
Shell lacks enough internal space for head and limbs
Forelimbs are modified as flippers
Hind limbs act as rudders
Most abundant and wide spread are the 2 species of
green sea turtles
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The largest of the turtles is the Atlantic Leatherback
Have a skin covering the shell
Reach 2 meters in length
Weigh more than 6oo kilograms (1300 pounds)
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All marine turtles are in danger of extinction:
1. breeding beaches are being developed
2. Their eggs and shells are in demand
3. They drown in fishing nets
4. Feeding areas are polluted
5. Floating plastic bags are mistaken for food and
eaten
Marine Crocodiles
 One living species
 Lives in mangrove swamps and isolated
mainland shores in the tropical western
Pacific
 Very aggressive and hunts in packs
 7 meters long
 Weighs over 2.000 pounds
Marine Lizards
 One surviving species – Galapagos Marine Iguana.
 Live among the intertidal rocks and beaches of the
Galapagos Islands
 Grow to more than 1 meter in length
 Weigh 9 kilograms (20 pounds)
 Swim by undulating body and tail
 Live in colonies and feed on off-shore seaweeds.
Sea Snakes
 50 species of sea snakes
 Most are native to the Indian Ocean and the western
Pacific areas
 There are none in the Atlantic
 They hunt among the coral heads
 Sea snakes must return to the surface to breathe
 The young are born alive in the water
 Venom is among the most powerful animal poison
known.
 Prey is held in the mouth until saliva which contains the
neurotoxin enters wounds and takes effect.
Marine Birds
 Marine birds:
 A. are endotherms – they generate and regulate
metabolic heat
 B. have thin hollow bones without fatty insulation
 C. have light weight beak replacing jaws and teeth
 D. 4 chambered heart to circulate blood under high
pressure
 E. have a respiratory system that can accept large
quantities of oxygen
 F. all birds lay eggs on land
 Only 3% of known birds are classified as sea birds.
 Sea birds have salt secreting glands in their head like
marine reptiles.
 4 Groups of sea birds:
 1. Tubenoses
 100 species – world’s most oceanic birds; examples –
albatrosses, petrels and shear waters
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Albatross;
Wingspan of 12 feet
Weighs 22 pounds
Wings are aerodynamic; can soar at high speeds using
very little energy
 2. Pelicans
 This group includes pelicans, cormorants, frigate birds,
and Boobies
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All have throat patches
All have webbed feet
They do not spend much time over open ocean
The frigate can not walk or swim; its skeleton weighs
less than its feathers
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4. Penguins
Have lost the ability to fly
Excellent swimmers
Have fatty insulation making
feathers greasy
 Neutrally buoyant; can dive to
depths of 875 feet and stay
submerged for 10 minutes
Marine Mammals
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3 Living groups
1. Cetacea – Porpoises, dolphins, and whales
2. Carnivora – seals, sea lions, walruses and sea otters
3. Sirenia – manatees and dugongs
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All exhibit mammalian characteristics:
A. endothermic
B. breathe air
C. give birth to living young
 D. young suckle milk produced in mammary glands
 E. have hair at some time during life
 All marine mammals have 4 common features:
 1. Streamlined body shape with limbs adapted for
swimming (drag is reduced by a slippery skin or hair
covering)
 2. They generate internal body heat through high
metabolic rate and conserve the heat by layers of
insulation (fat or fur)
 3. A respiratory system modified to collect and retain
large amounts of oxygen.
 4. Many osmotic adaptations allow marine mammals to
do away with the need for fresh water.
 Order Cetacea (whales)
 90+ species
 Range in size from 6 feet to 110 feet
 Can weigh up to 110 tons
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Suborder Odontoceti (toothed whales)
Have teeth and are active predators
Have a high brain weight to body weight ratio
Use echolocation (biological answer to sonar) to find
prey
 Suborder Mysticeti
 Baleen whales – have no
teeth; filter feeders
 (blue whales, humpback, and
grey whales)
Order Carnivora
 Suborder Pinnipedia
 (seals, sea lions, and walruses)
 True seals – smooth head, no external ears
 Elephant seals have diving record of 5,120 feet.
 Suborder Fissipedia
 Sea Otter
Order Sirenia
 Bulky, small brained manatees and dugongs
 Herbivores 15 feet; 1500 pounds