The Invertebrates
• The invertebrates are comprised of an
assemblage of about 34 phyla of Metazoa
and about 18 phyla of protists the
Protozoa.
Hallucigenia sparsa
Hallucigenia sparsa an Onychophoran from the Burgess
Shale deposits of Canada
Animal Bauplan
Symmetry and complexity
(Zoo 1604 review)
What is a “Bauplan”?
• Bauplan is a German word meaning
building plan or blueprint.
• It is used by biologists to refer to the
overall and consistent structure of a
group of organisms.
--The animal bauplan
--The Annelid bauplan, etc
Chordata
Arthropoda
Annelida
Mollusca
Protostomes
Hemichordata
Echinodermata
Deuterostomes
Coelomates
†
Triploblasts
* Diploblasts
Acoelomates
Bilateria†
Mesozoa
Pseudocoelomates
Radiata*
Eumetazoa
Metazoa
Protozoa
Monera (Bacteria)
Cnidaria
Ctenophora
Parazoa
Body Plan
Animals are divided into groups based on
body architecture.
I.
II.
III.
IV.
Grades of Complexity
Major body types
Symmetry
Cleavage
I. Grades of Complexity
1. Protoplasmic: all functions take place in
single cell, or each cell (if colonial).
I. Grades of Complexity
1. Protoplasmic: all functions take place in
single cell, or each cell (if colonial).
2. Cellular: there is a division of labor
among cells, but no segregation of cells
that perform the functions.
I. Grades of Complexity
1. Protoplasmic: all functions take place in
single cell, or each cell (if colonial).
2. Cellular: there is a division of labor
among cells, but no segregation of cells
that perform the functions.
3. Tissue: specialized cells segregate organ,
or organ-system: there is segregation of
tissues.
Spongilla lacustris
Chordata
Arthropoda
Annelida
Mollusca
Protostomes
Hemichordata
Echinodermata
Deuterostomes
†
Triploblasts
* Diploblasts
TISSUE
Coelomates
Pseudocoelomates
Acoelomates
Bilateria†
Radiata*
Eumetazoa
Mesozoa
Cnidaria
Ctenophora
Parazoa
Metazoa
Protozoa
Monera (Bacteria)
CELLULAR
PROTOPLASMIC
II. MAJOR BODY TYPES
1. Cell aggregate
II. MAJOR BODY TYPES
1. Cell aggregate
2. Blind sac
II. MAJOR BODY TYPES
1. Cell aggregate
2. Blind sac
3. Organs in tissue or
body cavity
Cell aggregate:
• There is no gut, energy absorption
throughout.
• No germ layers, no true tissues or organs.
Example:
sponges
(Phylum
Porifera)
Sac-like body plan
• Has only one opening for both food intake and
waste removal. Sac-like body plan animals do
not have tissue specialization or development of
organs. (Diploblastic: two cellular germ layersendoderm and ectoderm)
Example: jellyfish
Phylum (Cnidaria)
Organs in tissue or body cavity Fig. 3.5
Acoelomates Pseudocoelomates Coelomates
Principal body plans of triploblastic Metazoa
Fig. 3.5 page 48
Ectoderm (Epidermis)
Mesoderm (Mesenchyme,
Muscles, etc)
Entoderm (Gastrodermis,
Gut)
Parietal peritoneum
(Mesoderm)
“Tube-within-a-tube”
• Two openings: one for food to enter the body
(mouth), one for wastes to leave the body
(anus).
--The tube-within-a-tube allows
specialization of parts along the tube
• Animals with the “tube-within-a-tube”
plan are 10% more efficient at digesting
and absorbing their food than animals
with the sac-like body plan.
Chordata
Arthropoda
Annelida
Mollusca
Protostomes
Hemichordata
Echinodermata
Deuterostomes
†
Triploblasts
* Diploblasts
ORGANS IN
TISSUE OR
BODY
CAVITY
Coelomates
Pseudocoelomates
Acoelomates
Bilateria†
Radiata*
Eumetazoa
Mesozoa
Cnidaria
Ctenophora
Parazoa
Metazoa
Protozoa
Monera (Bacteria)
BLIND
SAC
CELL
AGGREGATE
III. Symmetry
• Asymetrical animals: no general body plan
or axis of symmetry.
III. Symmetry
• Asymetrical animals: no general body plan
or axis of symmetry.
• Radially symmetrical: body parts
organized about a central axis and tend to be
cylindrical in shape.
III. Symmetry
• Asymetrical animals: no general body plan
or axis of symmetry.
• Radially symmetrical: body parts
organized about a central axis and tend to be
cylindrical in shape.
• Bilaterally symmetrical: a single plane of
symmetry that produces mirror halves.
Spongilla lacustris Plane of symmetry none
Radial
Plane of
symmetry
Many
Bilateral
One
Chordata
Arthropoda
Annelida
Mollusca
Protostomes
Hemichordata
Echinodermata
Deuterostomes
†
Triploblasts
* Diploblasts
BILATERAL
Coelomates
Pseudocoelomates
Acoelomates
Bilateria†
Radiata*
Eumetazoa
Mesozoa
Cnidaria
Ctenophora
Parazoa
Metazoa
Protozoa
Monera (Bacteria)
RADIAL
ASYMMETRICAL
IV. Cleavage
• Cleavage is the initial process of development
after fertilization of the egg.
Blastomere
Zygote
(fertilized
egg)
Blastomere
(large
group of
cells)
Cleavage planes are symmetrical to the polar axis
Regulative development
Cleavage planes are oblique to the polar axis
Mosaic development
SPIRAL
Chordata
Arthropoda
Annelida
Mollusca
Protostomes
Echinodermata
Deuterostomes
†
Triploblasts
* Diploblasts
RADIAL
Hemichordata
Coelomates
Pseudocoelomates
Acoelomates
Bilateria†
Radiata*
Eumetazoa
Mesozoa
Cnidaria
Ctenophora
Parazoa
Metazoa
Protozoa
Monera (Bacteria)
The Big Picture
• Bauplan define animals and the groups within animals.
• Invertebrates can be divided into groups based on:
-- Grades of Complexity
-- Major body types
-- Symmetry
-- Cleavage
• Thus, for every invertebrate group, you should be able
to know these characteristics.
Chordata
Arthropoda
Annelida
Mollusca
Protostomes
Hemichordata
Echinodermata
Deuterostomes
Coelomates
†
Triploblasts
* Diploblasts
Acoelomates
Bilateria†
Mesozoa
Pseudocoelomates
Radiata*
Eumetazoa
Metazoa
Protozoa
Monera (Bacteria)
Cnidaria
Ctenophora
Parazoa
Molluscs
•
•
•
•
Grade of Complexity: Tissue
Major body type: Eucelomate
Symmetry: Bilateral
Cleavage: Spiral
B & B: Chapter 3 pp. 49-88