NONVERTEBRATE CHORDATES,
FISHES, AND AMPHIBIANS
Ms. Moore
3-1-13
WHAT IS A CHORDATE?
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Phylum: Chordata
A chordate is an animals that has, for at least
some stage of life, a dorsal, hollow nerve cord; a
notochord; pharyngeal pouches; and a tail
that extends beyond the anus.
Hollow nerve cord: nerves branch off and connect to
organs
 Notochord: long supporting rod that runs through the
body just below the nerve cord
 Pharyngeal pouches: paired structures in the throat
region; can develop slits  gills in some chordates
 Tail: can contain bone and muscle; can be used for
motility
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CHARACTERISTICS OF CHORDATA
MOST CHORDATES ARE VERTEBRATES
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Figure 30-2
96% of all chordates are placed in the subphylum:
Vertebrata  vertebrates
Vertebrae: backbone replaces the notochord in most
developing vertebrates; encloses and protects the
spinal cord
Part of endoskeleton
 Grows as the animal grows
 Made up of living and non living cells
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NONVERTEBRATE CHORDATES
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2 groups of Chordata do not have a backbone
Soft bodied marine animals
 550 mya = ancestors!
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Tunicates
Subphylum: Urochordata
 Filter feeders
 Open Circulatory
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Lancelets
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Subphylum: Cephalochordata
Small fishlike creatures
Live on sandy ocean body
Closed Circulatory
Diffusion through skin
MINI LAB
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Draw a picture depicting a typical:
Tunicate (p 769)
 Lancelet (p 770)
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Label all parts
WHAT IS A FISH?
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Fishes are aquatic vertebrates, most fishes have
paired fins, scales, and gills.
Fins = movement
 Scales = protection
 Gills = exchanging gases
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EVOLUTION OF FISHES
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The evolution of jaws and paired fins were important
developments during the rise of fishes.
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First Fishes: 510 mya
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The Age of Fishes: 505-410 mya
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Jawless with armored plates
Ancestors of hagfishes and lampreys
Arrival of Jaws and Paired Fins
Filter feeders  herbivores and carnivores
Fins attached by cartilage  movement
 Cartilage: strong tissue that supports the body; softer and
more flexible than bone
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Modern Fishes
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Ancestors of sharks and rays: cartilage
Bony fishes: bone
FORM AND FUNCTION IN FISHES
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Feeding
Herbivores, carnivores, parasites, filter feeders, and
detrius feeders
 Mouth  Esophagus  Stomach  other organs 
Intestines  Anus
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Respiration
Gills: located on either side of the pharynx;
made up of feathery filaments
 Lungs: specialized organs to help in shallow
waters
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Circulation
Closed circulatory system: single loop
 Heart  gills  body  heart
 Atrium: large muscular chamber located in the
heart
 Ventricle: thick-walled, muscular chamber;
pumping portion of the heart
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Response
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Fishes have well-developed nervous systems organized
around a brain
Cerebrum: voluntary activities; senses
 Cerebellum: coordination
 Medulla oblongata: fx of organs
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Lateral line system: sense vibration/movement
Movement
S-shaped movement—muscles in the back
 Fins increase surface area = faster
 Swim bladder: gas filled organ that adjusts buoyancy
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Reproduction
Eggs can be fertilized externally or internally
 Oviparous: eggs hatch outside the mother’s body; salmon
 Ovoviviparous: eggs stay in the mother’s body after
internal fertilization; guppy
 Viviparous: embryos stay in the mother’s body after
internal fertilization; some sharks
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GROUPS OF FISHES
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Jawless Fishes
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Class: Agnatha
No true teeth or jaws
Skeletons made of fibers and cartilage (keep notochords)
Include:
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Sharks and Relatives
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lampreys—filter feeders as larvae/parasites as adults
Hagfishes—detrius feeders; slime; 6 hearts; open; knots!
Class: Chondrichthyes (a.k.a. cartilage)
Include: sharks, rays, skates, and others
Bony Fish
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Class: Osteichthyes
Skeleton made of bone
Almost all include ray-finned fishes
ECOLOGY OF FISHES
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Aquatic Life
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Freshwater = low salt
concentration
Ocean = high salt concentration
Movement/Migration
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Anadromous fishes: ocean
dwellers migrate to freshwater to
breed
Lampreys
 Salmon
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Catadromous fishes: freshwater
fishes migrate to ocean to breed
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European eels
MINI LAB
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Draw the diagram of the fish, label all parts
(p774)
Draw the diagram of a fish brain, label all parts
(p777)
Fill out long study guide Agnatha 
Osteichthyes
Complete handout
WHAT IS AN AMPHIBIAN?
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An amphibian is a vertebrate that, with some
exceptions, lives in water as a larva and on land
as an adult, breathes with lungs as an adult, has
moist skin that contains mucous glands, and
lacks scales and claws.
Evoultion of Amphibians:
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Bones became stronger = movement on land
Lungs = breath air
Sternum = protection of organs
FORM AND FUNCTION IN AMPHIBIANS
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Feeding
Tadpoles: filter feeders or herbivores (algae) with
long intestines
 Adult: meat-eating with shorter intestines
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Sticky tongues to catch prey
 Mouth  esophagus  stomach  intestine 
liver/pancreas/gallbladder  colon  cloaca (digestive
wastes, urine, eggs/sperm leave body)
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Respiration
Larval: gas exchange through skin/gills
 Adult: lungs some skin/mouth cavity (always
exceptions—lung less salamanders)
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Circulation
Double loop system: first carries O2 rich blood from
heart to lungs and skin and back; second carries O2
rich blood from heart to rest of body and back
 3 chambers: left atrium, right atrium, and ventricle
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Excretion
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Kidneys  ureters  bladder/cloaca
Reproduction
Frog eggs laid in water to undergo external
fertilization
 Eggs hatch into tadpoles
 Tadpoles gradually grow limbs, lose tails/gills, and
become carnivorous
 Young adults move onto land
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Movement
Larva: move like fishes
 Adult: use front and back legs to move in a variety of
ways
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Response
Brain much like a fish
 Well developed nervous and sensory systems
 Nictitating membrane: protects eye from
underwater damage/keeps moist
 Tympanic membrane: eardrums on each side of the
head
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GROUPS OF AMPHIBIANS
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Salamanders (and Newts)
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Frogs and Toads
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Order: Urodela
Long bodies and tails; most have 4 legs
Larva and adults are carnivorous
Moist environment or underwater
Order: Anura
Jump! Frogs = long legs, near water; Toads = shorter legs;
moist woods, even deserts
Caecillians
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Order: Apoda
Legless, carnivorous, live in water or burrow in moist soil,
many have fishlike scales in skin
ECOLOGY OF AMPHIBIANS
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Must live near water
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Some exceptions: desert amphibians have special
adaptations
Protection from predators
Skin colorings/markings
 Poison glands in skin
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Global decline
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Amphibians are very susceptible to the environment
MINI LAB
Draw the following in your lab manual:
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Figure 30-23 (p784)
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Figure 30-24 (p785)
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Notice the location of the organs
Use different colors to demonstrate the direction of
blood throughout the amphibian
Create a life cycle for an amphibian
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Can use figure on p786