VERTEBRATE ZOOLOGY
(VZ Lecture02 – Spring 2012 Althoff - reference PJH Chapters 1-2)
DIVERSITY,
CLASSIFICATION &
EVOLUTION
PART II
1
2
Branchiostoma
Amphioxus-like
nonvertebrate
chordate
4
3
1
2
Hypothetical
primitive
vertebrate
Fig. 2-4 p4 PJH
4
3
Basics of Vertebrate Design
(reference Table 2.1 PJH)
FEATURE
A
Generalized Nonvertebrate Primitive Vertebrate
No cranium
Simple brain
No specialized sense organs
(except photoreceptors)
Poor distance sensation
(but sensitive skin)
No electroreception
Cranium
Tripartite brain
Multicellular sense
organs (eye,
nose, inner ear)
Improved distance
sensation; lateral
line system
Electroreception
in primitive form
HINDBRAIN
MIDBRAIN FOREBRAIN
________________ BRAIN
Basics of Vertebrate Design
(reference Table 2.1 PJH)
FEATURE
B
Generalized Nonvertebrate Primitive Vertebrate
Gill arches for filter feeding
(respiration by diffusion)
Numerous gill slits & arches
(up to 100 per side)
Pharynx not muscularized
(w/ exceptions)
Water moved through pharynx
and over gill arches by
ciliary action
Gill arches made of collagen
mucoscleroproteins
Gill arches support
gills used for
respiration
Few gill slits (6-10
per side); gill
filaments complex
Pharynx muscularized
(specialized)
Water moved by
active muscular
pumping
Gill arches made of
cartilage—allows
elastic recoil & thus
aids in pumping
Basics of Vertebrate Design
(reference Table 2.1 PJH)
FEATURE
C
Generalized Nonvertebrate Primitive Vertebrate
Gut not muscularized, food
passage by ciliary action
Digestion of food is intracellular;
Cells lining gut take in
individual food particles
No discrete liver and pancreas;
midgut cecum or diverticulum
is probably homologous to both
Gut muscularized,
food moves by
peristalsis
Digestion of food is
extracellular;
Enzymes poured
onto food in gut
lumen
Discrete liver and
pancreatic tissue
Basics of Vertebrate Design
(reference Table 2.1 PJH)
FEATURE
D
Generalized Nonvertebrate Primitive Vertebrate
No true heart (ventral pumping
structure (vessels)
Ventral pumping heart
3-chambered
peristalsis
No neural control of pumping
Neural control of
pumping (except
hagfishes)
Open circulatory system, minimal Closed circulatory
capillary system
system
Blood not specifically involved
Blood specifically
in transport of O2 and CO2
involved in O2 &
CO2 transport
No red blood cells or respiratory
Red blood cells with
pigments
hemoglobin
Basics of Vertebrate Design
(reference Table 2.1 PJH)
FEATURE
E
Generalized Nonvertebrate Primitive Vertebrate
No specialized kidney; coelum
filtered by flame cells
Flame cells empty into atrium
then out atriopore
Body fluid concentrations and
ionic composition = seaH20
No kidney present to regulate
Specialized glomerular
kidney; segmental
structures along
dorsal body wall
Empty to ‘outside” via
archinephric ducts
leading to cloaca
Body fluids more dilute
than seawater
Kidney regulates fluid
volume, where
nitrogen excretion
occurs
GLOMERULAR
STRUCTURE
IN KIDNEY
FLAME CELL
Note: example here is
of planaria
(non-chordate)
Basics of Vertebrate Design
(reference Table 2.1 PJH)
FEATURE
F
Generalized Nonvertebrate Primitive Vertebrate
Notochord provides main support Notochord provides
for body muscles
main support for
body muscles plus
vertebral elements
around nerve cord
(except hagfishes)
Myomeres with simple V-shape
Myomeres more
complex W-shape
No lateral fins or medial fins
Primitively, no lateral
beside tail fin
fins. Caudal fin
has dermal fin rays.
No dorsal fins
Dorsal fins present
(except hagfishes)
AMPHIXOUS
LAMPREY
SHARK (DOGFISH)
Fig. 2-10 p33 PJH
BONY FISH (perch)
Embryology
& Germ Layers
• All animals except sponges (Porifera) form
distinct tissue (germ) layers. For
vertebrates, 3 germ layers form during
embryonic development
• 3 layers: ectoderm, mesoderm, endoderm
• Each has enabled refinements in organsystems
Pharyngula state of embryonic development
ECTODERM
Gut endoderm
ECTODERM
Fig. 2-5 p26 PJH
Germ Layers: ECTOderm
• forms superficial layers of skin in adults,
linings of most anterior and most posterior
parts of the digestive tract and the nervous
system (including most of the sense
organs…eyes and the ear
• How can it be the “ecto” layer if it lines
much of the digestive tract?
Germ Layers: ENDOderm
• forms balance of digestive tract as well as
lining of glands associated with the gut (i.e.,
pancreas, gall bladder, liver). Linings of
most respiratory surfaces of vertebrate gills
and lungs
Germ Layers: MESOderm
• The last of the 3 germ layers to appear
during embryonic development
• Forms everything else:
muscles
skeleton (including notochord)
connective tissue
circulatory system
urogenital system
• Further along in development, mesoderm
forms the coelom (body cavity)
pleuroperitoneal & pericardial cavities…
in gut the cavity is lined by mesenteries
Pharyngula Stage (Fig. 2-5, p26)
• In most vertebrates, the linings of the
pharyngeal pouches result in 6 or more
glandular structures including….
Lymphatic system
thymus gland
parathyroid glands
carotid bodies
tonsils
• During this stage, the embryo is a mix of
______________ and
___________________components
Pharyngula Stage and beyond
• Gives rise to _______________ (running
from the head end to the tail end
• __________ eventually form:
dermis of the skin
striated muscles of the body used in
locomotion
portions of the skeleton (vert. column &
back of head)
5 Tissue Types in ADULT vertebrates
•
•
•
•
•
Epithelial
Connective
Vascular (blood)
Muscular
Nervous
Most of these tissue have, as fundamental
component, the fibrous protein ________. Other
key component fibrous proteins that may be
present include _________ and _________.
Integument
• External covering of vertebrates
• Makes up ________ of body weight in most
vertebrates…more in armored species
• Includes skin and deriatives (i.e., glands,
scales, dermal armor, and hair)
• 3 layers:
epidermis—outer layer
dermis—middle “unique” layer
subcutaneous tissue layer
(hypodermis)
Important Mineral
• Unique to vertebrates: type of mineral
called ________________. A complex
compound of ____ and ____.
• This mineral more resistant to acid than
calcium carbonate (in mollusk
shells)…an may explain how
vertebrates can resist tissue damage
when engaged in muscular activity that
can release lactic acid into the blood
Mineralized tissues…
• Six types possible in vertebrates:
________ (adults only, 99% of composition)
________ (adults only, 90% of composition)
_______ (adults only, ~ 50% of composition)
_________ – not mineralized in most
vertebrates, sharks major exception
_________—primitive verte. & today’s
fishes
__________—bonelike, mostly found
only in mammals (fastens teeth to
sockets)