Chapter 34
Vertebrates
4 derived characters of Chordates:
1. Notochord – flexible rod which supplies structural support
2. Dorsal, hollow nerve cord – develops into central
nervous system (brain & spinal cord)
3. Pharyngeal slits – allows water to exit mouth without
going through entire digestive tract
4. Muscular, post-anal tail
Fig. 34-3
Dorsal,
hollow
nerve cord
Muscle
segments
Notochord
Mouth
Anus
Muscular,
post-anal tail
Pharyngeal
slits or clefts
3 subphyla of Phylum Chordata:
1. Subphylum Urochordata (invert. chordate)
a. tunicates or sea squirts
b. marine, suspension-feeders
c. have all 4 chordate characteristics in the larval
stage (only pharyngeal slits as adults)
Fig. 34-5
Incurrent
siphon
to mouth
Water flow
Notochord
Dorsal, hollow
nerve cord
Excurrent
siphon
Atrium
Pharynx
with
slits
Tunic
Excurrent
siphon
Tail
Muscle
segments
Incurrent
siphon
Intestine
Anus
Intestine
Esophagus
Stomach
An adult tunicate
Excurrent
siphon
Stomach
Atrium
Pharynx with slits
A tunicate larva
2. Subphylum Cephalochordata (invert. chordate)
a. Lancelets
b. marine, suspension-feeders
c. have all 4 chordate characteristics in adult stage
Fig. 34-4
Cirri
2 cm
Mouth
Pharyngeal slits
Atrium
Notochord
Digestive tract
Atriopore
Dorsal, hollow
nerve cord
Segmental
muscles
Anus
Tail
3. Subphylum Vertebrata
Characteristics of Vertebrates
1. Neural crest – mass of cells near the margins of the
embryonic folds that form the neural tube
Characteristics of Vertebrates
2. Pronounced cephalization – well-developed head with
braincase (skull)
3. Vertebral column – endoskeleton; spinal cord
4. Closed circulatory system – allows for active
metabolism
5. Heart with at least 2 chambers, red blood cells
with hemoglobin and kidneys
Fig. 34-2b
Phylogeny & Taxonomy of Vertebrates
Myxini
(hagfishes)
Petromyzontida
(lampreys)
Head
Chondrichthyes
(sharks, rays, chimaeras)
Vertebral column
Actinopterygii
(ray-finned fishes)
Jaws, mineralized skeleton
Actinistia
(coelacanths)
Lungs or lung derivatives
Dipnoi
(lungfishes)
Lobed fins
Amphibia (frogs,
salamanders)
Legs
Amniotic egg
Reptilia
(turtles, snakes,
crocodiles, birds)
Mammalia
Milk (mammals)
Class Myxini (Hagfishes)
•
•
hagfishes lack jaws and vertebrae
all marine
http://dsc.discovery.com/videos/nasty-by-nature-video/
Hagfish
Class Petromyzontida (Lampreys)
1. Lack jaws, have notochord
2. M and FW
Figure 34.10
Gnathostomata
•
Have hinged jaws (dorsoventrally)
–
origin of jaw was major event
Fig. 34-13-3
Gill slits
Cranium
Mouth
Skeletal rods
Class Chondrichthyes (cartilaginous fishes)
1.
2.
3.
4.
5.
Cartilaginous endoskeleton
750 sp.
aquatic
Jaws and paired fins are well developed
2 subclasses:
a. Sharks, rays & skates
b. Chimaeras or ratfishes
Sharks
1. Streamlined body
•
Swift and powerful swimmers
2. Obtain buoyancy by storing large amounts of oil in
the liver
3. Many carnivorous, but largest sharks and rays feed
on plankton
Fig. 34-15
Pectoral fins
Pelvic fins
(a) Blacktip reef shark (Carcharhinus
melanopterus)
(b) Southern stingray (Dasyatis americana)
(c) Spotted ratfish (Hydrolagus colliei)
Rays
1. Flattened bottom dwellers
2. Enlarged pectoral fins
3. Tail may bear venomous barbs
Osteichthyes (bony fishes)
1.
2.
3.
4.
5.
Bony endoskeleton
Most numerous group of vertebrates (30,000 sp.)
Aquatic
Lateral line system
Breathe by drawing water over gills protected by an
operculum
6. Swim bladder (air sac)– helps control buoyancy
7. Reproduction varies extensively
–
Most species are oviparous, some are viviparous
Fig. 34-17
(a) Yellowfin tuna (Thunnus albacares)
(b) Clownfish (Amphiprion ocellaris)
(c) Sea horse (Hippocampus
ramulosus)
(d) Fine-spotted moray eel
(Gymnothorax dovii)
8. 3 classes:
a. class Actinopterygii –
e.g., bass, trout, perch, tuna, herring, etc.
b. class Actinistia –
e.g., coelacanths – gave rise to the tetrapods
c. Class Dipnoi - lungfishes
perch
bass
The Tetrapods
– Amphibians, reptiles, birds, mammals
Class Amphibia – (two lives)
1.
2.
3.
4.
5.
6.
First land vertebrates
6150 sp.
Exchange gases through skin
Lay unshelled eggs in moist environment
Most undergo metamorphosis
3 extant orders:
a. Order Urodela – salamanders
b. Order Anura – frogs
c. Order Apoda - caecilians
Fig. 34-21
(a) Order Urodela
(b) Order Anura
(c) Order Apoda
Amniotic Egg
1. Shelled, water-retaining egg
2. Contain specialized membranes (amnion,
chorion, allantois, yolk sac)
3. Allowed vertebrates to reproduce on land
Fig. 34-25
Chorion
Amnion
Allantois
Yolk sac
Embryo
Amniotic
cavity
with
amniotic
fluid
Shell
Yolk
(nutrients)
Albumen
Class Reptilia
1.
2.
3.
4.
5.
Water-proof scales
6500 sp.
Shelled amniotic egg
Exchange gases mostly through lungs
Internal fert. – mostly oviparous, but some
viviparous
6. Ectothermic
7. 4 extant orders:
Order Testudines – turtles
Order Sphenodontia - tuataras
Order Squamata – snakes & lizards
Order Crocodilia – crocodiles & alligators
Fig. 34-27
(a) Tuatara (Sphenodon punctatus)
(b) Australian thorny devil
lizard (Moloch horridus)
(c) Wagler’s pit viper
(Tropidolaemus wagleri)
(d) Eastern box turtle
(Terrapene carolina carolina)
(e) American alligator
(Alligator mississippiensis)
Order Testudines
Order Sphenodontia
Order Squamata
Order Crocodilia
Class Aves
1. Evolved from a reptile (amniotic egg, scales on the
leg)
2. 8,600 sp. (28 orders)
3. Endothermic
4. Four-chambered heart
5. Body anatomy modified for flight (carinates)
a. Hollow bones
b. Absence of some organs
c. Teeth modified into a beak (gizzard)
d. Feathers
e. Wings
Fig. 34-28
Finger 1
(b) Bone structure
Palm
Finger 2
(a) Wing
Forearm
Shaft
Vane
Finger 3
Wrist
Shaft
Barb
Barbule
Hook
(c) Feather structure
Class Aves
6. some flightless birds – ratites
e.g., ostrich, emu
Class Mammalia
1.
2.
3.
4.
5.
6.
7.
5,300 sp.
Hair and mammary glands (milk)**
Endothermic and active metabolism
Four-chambered heart
Diaphragm helps ventilate the lungs
Hair and a layer of fat help retain metabolic heat
Internal fert. with placenta which nourishes the
fetus
Class Mammalia
8. Larger brains than other vertebrates of similar size
and many are capable of learning
9. Different size and shape teeth
10. 3 major groups of mammals:
a. Monotremes – egg laying mammals
e.g., platypuses, echidna (Australia & New Guinea)
echidna
platypus
b. Marsupials – mammals with pouches
e.g., kangaroos, koalas, opossums
(Australia)
The End