Outline for Vertebrates – student notes – Biology 520
I. Phylum Chordata
Biodiversity links | Encyclopedia of life | Wild Finder | Arkive | simulations of dinosaurs and
other prehistoric life (interactive site from BBC) | family tree p. 758 fig 26-5
A. general characteristics (shared by all at some point during development; see p.
575, fig 26-4)
1. dorsal, hollow nerve chord (other phyla have solid ventral nerve
chords)
2. notochord – flexible material located between the nerve chord
and the gut. (Degenerates into the discs between the vertebrates in
humans.)
3. pharyngeal slits – these are what look like "gill slits" in
developing mammal embryos. They develop into gills openings in
fish, and into other structures in mammals etc.
4. post-anal tail that does not include any of the digestive system.
B. subphyla cephalochordata and urochordata are little-known non-vertebrate
chordates.
· lancelets and tunicates
II. Subphylum vertebrata
A. characteristics
1. vertebrae and internal skeleton
2. 2 pairs of appendages
3. head with highly developed sense organs
4. highly specialized brain
5. closed circulatory system
B. homeostasis - the process of maintaining a constant internal environment.
Vertebrate bodies are designed with specialized systems to help them do this:
1. nervous system - communication and integration of senses
2. endocrine system - chemical communication (hormones) that
regulate growth, levels of sugar and other substances in the blood,
etc. Involves the liver and various glands.
3. muscles/skeletal - movement
4. circulatory - brings oxygen and sugar to the cells and carries
away carbon dioxide and waste products.
5. digestive – enzymes break down food to sugar, which enters the
circulatory system.
6. excretory – kidneys, colon take care of cellular wastes and
poisons and solid waste
· reminder – all of these functions are controlled by enzymes and
other proteins, which are made by DNA.
C. class Agnatha (aye-nath-ah) fish without jaws (p. 759)
1. hagfish – scavengers
2. lampreys – blood suckers
D. class Chondrichthyes – cartilaginous fishes
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explore shark anatomy
check out the diversity - info on different species
1. skeleton made of cartilage
2. no swim bladder – "swim or float"
3. gills for oxygen
4. excellent senses
5. some bear live young; all have internal fertilization
6. excretory, digestive, and reproductive systems have a common
opening – the cloaca
E. class Osteichthyes - bony fishes - p. 760-761
1. members of the little-known subclass, lungfishes, can breathe air
and creep on their fins; they have been proposed as "transitions"
between fish and amphibians.
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another odd bony fish (in the same subclass) is known as
the coelocanth. These fish were originally known only from
fossils, and were found live more recently. They are known
as "fleshy-finned" fish. More here
pictures and info about other "odd fish"
2. swim bladder allows them to "hover" in the water
3. gills and two-chambered heart [You should be able to explain
circulation pattern; see fig. 27-11, p. 792]
4. external fertilization and eggs
5. can be herbivores or carnivores
6. very streamlined body for motion in water; appendages not need
to support body but are used only to steer and maintain balance
(fins)
7. divided into 24 orders
F. class Amphibia (see p. 761)
1. external fertilization and metamorphosis
2. most live in aquatic environments, and can breathe through their
skin.
3. orders:
a. frogs and toads (no tail)
b. salamanders (have a tail)
c. caecilians (no legs)
4. three chambered heart (less efficient). [You should be able to
explain circulation pattern; see fig. 27-11, p. 792]
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how do frogs survive the winter??
explore amphibian embryology
G. Class Reptilia (see p.762-763)
1. scaly skin (not slimy!)
2. internal fertilization; eggs are soft-shelled and amniotic
3. can live in wet or dry environments and even in the ocean
4. "cold blooded" or ectothermic – rely on sun’s energy to warm
them
5. taxonomy – orders
a. turtles | browse the phylogeny (ancestry) of
turtles
b. snakes and lizards
c. crocodiles and alligators
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explore crocadile anatomy
explore the different species of crocodilians
6. dinosaurs were reptiles (what makes a dinosaur a dinosaur?)
check out skulls of various tetrapods: anapsids | synapsids |
diapsids
7. conventional theory says that birds evolved from
reptiles/dinosaurs (temperature control is one of the major
differences)
8. reptile hip and shoulders are designed differently from those of
mammals and dinosaurs. This results in a different walking style.
9. three or four chambered heart
F. Class Aves – birds – p. 763
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online bird guide
bird anatomy
Life of Birds
1. feathers
2. migration
3. light, hollow bones and other adaptations for flight.
4. muscles attached to a strong, keeled sternum for flight
5.amniotic eggs
6. one-way breathing pattern (see fig 31-6)
7. warm-blooded or "endothermic"
8. herbivores, carnivores, omnivores, and scavengers
9. four-chambered heart [You should be able to explain circulation
pattern]
10. migration
11. descended from reptiles? (Archaeopteryx)
12. very diverse group - 27 orders
G. Class Mammalia – p. 764
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North American mammals
Mammal exhibit at the Natural History museum
1. mammary glands, inner ear bones, distinctive skulls, high level
of parental care
2. fur/hair
3. endothermic
4. four-chambered heart. [You should be able to explain circulation
pattern]
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try your hand as a heart doctor at the Virtual Cardiology
Lab
check out the visible human heart
5. varied sizes of teeth and size of intestines (fig. 27-3) can be used
to infer diet
6. evolved from reptiles (Therapsids)
7. bear live young
8. jaw attached differently from reptiles – the same bone is a jaw
hinge in reptiles and the inner ear of mammals
9. taxonomy:
a. order Monotremes - platypus and echidna (spiny
anteater)
-mammary glands
-eggs
-cloaca
-no teeth
b. order Marsupials – young are born early and
develop further in pouch
-previously much more common in
South America
c. other mammal orders are all placental, meaning
their young develop fully before birth and receive
nourishment through a placenta
examples of placental mammal orders:
-rodents
-insectivores
-elephants
-primates
-carnivores (dogs, cats, seals, weasels)
-cetaceans (marine mammals)
-bats
-cows and deer (even toes)
-horses and rhinos (odd toes)
etc. – 17 total placental orders, plus 5 non-placental