Vertebrate Animals
Chapter 17b
• Characteristics of Phylum Chordata
• Major Evolutionary Novelties in the Chordates/Vertebrates
• Fishes
• Jawless Fish (Class Agnatha)
• Cartilaginous Fish (Class Chondricthyes)
• Bony Fish (Class Osteichthyes)
• Amphibians (Class Amphibia)
• Reptiles (Class Reptilia)
• Birds (Class Aves)
• Mammals (Class Mammalia)
• Primate
Evolution (Order Primata)
Chordates (Vertebrates) Are All In One Phylum
Figure 17.6
Survey of Living Things Grid
VERTE BRAT ES (mos t ly Chor dates)
vertebrates, hollow nerve cord, gill slits,
brain, skull
Jawless Fish (Class A gnatha)
feed by suction (vacuum mouth), no
paired fins
lampreys and hagfish
Cartilagi no us Fish (Cla ss Chon dri cht hyes)
moveable jaws, teeth, arrow scales,
cartila ginous skeleton
sharks, skates, rays
Bony Fish (Class Ostei cht hyes)
bony skeleton, operculum, fin rays, swim
bladder, flex. fins
trout, salmon, tuna, sardines, cod,
goldfish
Am phibians (Class Amphibia)
wet slimy skin, must live near water, legs
for crawling, gills as larvae but lungs as
adult, metamorphosis, evolved from
lobefin fish
ectotherms, air breathing lungs, amniotic
eggs, scales, shell, strong legs
frogs, toads, salamanders, caecilia ns
(legless)
hollow bones, feathers, beaks,
endotherms, lay eggs, can fly!, evolved
from reptiles
endotherms, fur, mammary g lands, big
brain, specialized dentition, most have
placenta and young are born live; evolved
from therapsid dinosaurs
Perching birds (jays, swallo ws,
sparrows, etc), raptors, gulls, waterfowl
Reptiles (Class Repti lia)
Birds (Class Aves)
Mammals (Class Mam malia)
turtles, lizards, snakes, alligators and
crocodiles, tuatara, dinosaurs
Egg layers: platypus, echidna
Pouch animals (marsupials): kangaroos,
opossums, koala bears
Placentals: dog, whale, deer, rabbit, bat,
primates (including humans)
The Vertebrate Genealogy
• Vertebrates
– Are represented by mammals, reptiles,
amphibians, and fishes.
– Have unique features, including the cranium and
backbone.
Nearly All Chordates are Vertebrates with a Skull and Spinal Vertebrae
Figure 17.29
Characteristics of All Chordates At Some Point During Their Lifetimes
Figure 17.30
Evolutionary Novelties/Landmarks of Phylum Chordata
• Development of hinged jaws
• Bony (calcium phosphate) skeleton instead of
cartilaginous skeleton
• Terrestrial Adaptations
– Internal lungs instead of external gills
– Four legs for walking on land
– Amniotic egg to avoid dehydration of embryo
– Endothermy instead of ectothermy
• Feathers or fur to maintain constant body temp.
Evolutionary Tree of the Chordates
Figure 17.32
Jawless Fish (Class Agnatha)
•
The first vertebrates probably
evolved about 542 million
years ago.
•
Cylindrical and elongated like
eels
•
Retention of all 7 gill slits as
adults, breathes using gills
•
No paired fins
•
Mouth is locked in a circular
sucker-shape (no jaws)
•
Skeleton made of cartilage
•
Parasitic on other fish
•
Includes the lampreys and
hagfish
Evolutionary Tree of the Chordates
Figure 17.32
Cartilaginous Fish (Class Chondrichthyes)
•
True hinged jaws
•
Predatory or filter feeding
carnivores
•
Skeleton of cartilage
•
5-7 gills slits (slightly fewer than
agnathans)
•
Paired pectoral fins used for
steering
•
Heterocercal (asymmetrical) tail
•
Mouth behind nose on ventral surface
•
Lateral line system of pores that detect
water currents and vibrations
•
Placoid scales (skin feels like
sandpaper) migrate anteriorly into
mouth
•
Includes the sharks, skates, and rays
Skate
Manta Ray
Shark Eating a Seal
Evolutionary Tree of the Chordates
Figure 17.32
Bony Fish (Class Osteichthyes)
•
Bony skeleton reinforced by hard
calcium salts
•
Flexible paired pectoral and pelvic
fins
•
Homocercal (symmetrical) tail
•
Single gill slit covered by
operculum (gill cover)
•
Swim bladder to maintain
buoyancy (forerunner of a lung?)
•
Terminal mouth (at very end)
•
Rounded scales (ctenoid or
cycloid)
•
Lateral line sensing system, keen
sense of smell and good eyesight
Clownfish and Anemone
Transition To Land and the Development of Legs
Figure 17.35
Evolutionary Tree of the Chordates
Figure 17.32
Amphibians (Class Amphibia)
•
A mixture of aquatic and terrestrial
adaptations
•
Semi-functional lungs to extract
oxygen out of air
•
Wet, slimy skin for diffusion of
oxygen from air
•
Four legs (a tetrapod) but relatively
weak pectoral and pelvic girdles
•
Metamorphosis from legless,
vegetarian with tail to four-legged,
carnivorous adult
•
Usually needs water for
reproduction to and to keep growing
embryos hydrated
•
Includes frogs, toads, newts, and
salamanders
Evolutionary Tree of the Chordates
Figure 17.32
Reptiles (Class Reptilia)
•
Dry, scaly skin to prevent water
loss
•
Stronger pelvic and pectoral
girdles to facilitate walking
•
Fully-functional lungs
•
Internal fertilization (no need
for water to reproduce)
•
Amniotic egg to keep growing
embryo wet
•
Ectothermic, as with previous
vertebrates
•
Most have bony teeth for
carnivorous diet
•
Includes snakes, lizards, turtles,
crocodiles, and alligators
Snake Ritual Wrestling
Galápagos Tortoise
Age of Reptiles: Mesozoic
• Dinosaurs included the largest animals ever to live on land.
Evolutionary Tree of the Chordates
Figure 17.32
Birds (Class Aves)
•
Birds evolved from a lineage of small,
two-legged dinosaurs
•
Hollow, air-filled bones to reduce
weight
•
Horny beak replaces teeth to reduce
weight
•
Feathers for flight and staying warm
(evolved from scales)
•
Scaly feet are remnants of reptilian
ancestry
•
Highly efficient, specialized lungs
•
Endothermic (maintain constant
internal body temp.)
•
Hard-shelled calcium eggs
•
Greatly enlarged sternum to anchor
flight muscles
Bird wings Are Airfoils Giving Them Lift When They Fly Forward
Flapping Geese
Soaring Hawk
Swans Taking Flight
Evolutionary Tree of the Chordates
Figure 17.32
Vertebrate Animals
Chapter 17b
• Characteristics of Phylum Chordata
• Major Evolutionary Novelties in the Chordates/Vertebrates
• Fishes
• Jawless Fish (Class Agnatha)
• Cartilaginous Fish (Class Chondricthyes)
• Bony Fish (Class Osteichthyes)
• Amphibians (Class Amphibia)
• Reptiles (Class Reptilia)
• Birds (Class Aves)
• Mammals (Class Mammalia)
• Primate
Evolution (Order Primata)
Mammals (Class Mammalia)
•
Arose about 200 million
years ago and were probably
small, nocturnal insecteaters.
•
Most mammals are
terrestrial
•
Fur or hair (endothermic)
•
Nearly all give birth to live
young (no egg-laying)
•
Suckle the young with breast
milk from mammary
glands
•
Most have special filtration
organ in uterus called a
placenta
Class Mammalia, Order Primata
• Early primates were arboreal
insectivores
• Opposable thumbs
• Stereoscopic vision
• Limber shoulder joints
• Eyes in front of the face
• Excellent eye-hand
coordination
• Extensive parental care
Evolution of Order Primata
Figure 17.41
Order Primata, The Old World and New World Monkeys
Figure 17.42c
Order Primata: The Apes or Hominids
Chimp Agonistic Behavior
Chimp Cracking Nut
Gibbons Brachiating
Vertebrate Animals
Chapter 17b
• Characteristics of Phylum Chordata
• Major Evolutionary Novelties in the Chordates/Vertebrates
• Fishes
• Jawless Fish (Class Agnatha)
• Cartilaginous Fish (Class Chondricthyes)
• Bony Fish (Class Osteichthyes)
• Amphibians (Class Amphibia)
• Reptiles (Class Reptilia)
• Birds (Class Aves)
• Mammals (Class Mammalia)
• Primate
Evolution (Order Primata)