Opener Chapter 7
Animal Organization
Pattern of Organization
• Asymmetry – i.e. ameoba
• Symmetry
– Radial symmetry- tube coral pulp
– Bilateral symmetry- insects
Asymmetry red encrusting sponge
Figure 7.8
Radial symmetry tube coral pulp
Bilateral animals
• Bilateral symmetry = important evolutionary
advancement
– Important for active, directed movement
• Anterior, posterior ends
– One side of body kept up (dorsal) vs. down (ventral)
Bilateral Symmetry
• Divided along sagittal plane into two mirror images
– sagittal= divides bilateral organisms into right and left
halves
•
•
•
•
Anterior= head end
Posterior= tail end
Dorsal= back side
Ventral= belly side
• Symmetry
– Median= sagittal
Directed movement evolved with anterior sense organs
cephalization
Cephalization
– specialization of sense organs in head end of animals
Other Patterns of Organization may reflect
evolutionary trends
• Unicellular (cytoplasmic)- organisms consist of single
cells or cellular aggregates,
– provide functions of locomotion, food acquisition,
digestion, water and ion regulation, sensory perception
and reproduction in a single cell.
Cellular aggregates
– Cellular aggregates consist of loose association, cells that
exhibit little interdependence, cooperation, or
coordination of function
– Some cells may be specialized for reproduction, nutritive
or structural function
• algae
• The analogy of a clock
– Can be used to place major events in the Earth’s
history in the context of the geological record
Cenozoic
Humans
~500 million years ago
Land plants
Origin of solar
system and
Earth
Animals
Algea
fossils
e 26.10
4
1
Proterozoic
Eon
Archaean
Eon
Billions of years ago
2
3
Multicellular
eukaryotes
Prokaryotes
Single-celled
eukaryotes
Atmospheric
oxygen
• Larger organisms do not appear in the fossil
record
– Until several hundred million years later
• Chinese paleontologists recently described 570million-year-old fossils
– That are probably animal embryos
(a) Two-cell stage
150 m
(b) Later stage 200 m
The Colonial
Connection
• The first multicellular organisms were colonies
– Collections of autonomously replicating cells
10 m
May Lead to Cell Specialization
• Organisms can have more than one tissue layer
– Diploblastic- two layers
What about Tripoblastic – three layers?
• Diploblastic Organization- Two tissue layers
– Cells are organized into tissues in most animal phyla
– Body parts are organized into layers derived from two
embryonic tissue layers.
– Ectoderm- Gr. ektos, outside + derm, skin gives rise to
the epidermis the outer layer of the body wall
– Endoderm- Gr. Endo, within, gives rise to the
gastrodermis that lines the gut
Mesoglea- between the ecto and endo and may or may not
contain cells
– Derived from ecto and/or endo
– Cells form middle layer (mesenchyme)
– Layers are functionally inderdependent, yet cooperate
showing tissue level organization i.e. feeding movements
of Hydra or swimming movements of a jellyfish
Figure 7.10
The Triploblastic (treis, three +blaste, sprout)
•
•
•
•
Animals described in chapters 10-22
Tissues derived from three embryological layers
Ectoderm- outer layer
Endoderm- lines the gut
• Mesoderm- meso, middle, Third layer between Ecto
and Endo
– Give rise to supportive cells
Figure 7.11
Diploblastic
Triploblastic
Diploblastic or Triploblastic?
Triploblastic animal
• Most have an organ system level of organization
• Usually bilaterally symmetrical or evolved from
bilateral ancestors
• Organized into several groups based on the presence
or absence of body cavity and for those that posses
one, the kind of body cavity present.
• Body cavity- fluid filled space in which the internal
organs can be suspended and separated from the body
wall
Body cavities are advantageous
1. Provide more room for organ development
2. Provide more surface area for diffusion of gases,
nutrients, and waste into and out of organs
3. Provide area for storage
4. Often act as hydrostatic skeletons (supportive yet
flexible)
5. Provide a vehicle for eliminating wastes and
reproductive products from the body
6. Facilitate increase in body size
What does acoelomate mean?
No coelom
Acoelomate a, without+ kilos, hollow
• Mesoderm relatively solid mass
• No cavity formed between ecto and endo
• These cells within mesoderm often called
parenchymal cells
• Parenchymal cells not speciallized for a particular fnc.
What’s a coelom?
• coelom=
– true body cavity
– Fluid-filled
– lined by mesoderm-derived epithelium
Earthworm
• Acoelomates lack a true body cavity
– Solid body
– no cavity b/w the digestive tract and outer body wall
Do these questions now…
• Think about aceolomate bilateral animals:
– To what domain do they belong
– “ ” kingdom ” ” ”
– What phyla include these organisms
• What is bilateral symmetry, and why was it an
important evolutionary advantage
movie
Acoelomate Bilateral Animals
• Consist of phyla:
– Phylum Platyhelminthes
– Phylum Nemertea
– Others…
Acoelomate Bilateral Animals
1.
Simplest organisms to have
bilateral symmetry
2.
Triploblastic
3.
Lack a coelom
4.
Organ-system level of
organization
5.
Cephalization
6.
Elongated, without
appendages
Reproductive and
osmoregulatory systems
Triploblastic Pseudocoelomate pseudes, false
• Body cavity not entirely lined by mesoderm
• No muscle or connective tissue associated with gut
• No mesodermal
The Triploblastic Coelomate Pattern
• Coelom is a body cavity completely surrounded by
mesoderm
• Peritoneum- mesodermal sheet that lines the inner
body wall and serosa (outer covering of visceral
organs)
• Having mesodermally derived tissue (muscle,
connective tissue) enhances the function of all internal
body systems.
Figure 7.12
Review of Animal Classification
Common names
• Crawdads, crayfish, or crawfish?
• English sparrow, barn sparrow, or a house sparrow?
Problem with common names
• Vary from region to region
• Common names often does not specify particular species
Binomial system of Nomenclature brings order
to a chaotic world of common names
• Universal
• Clearly indicates the level of classification
• No two kinds of animals have the same binomial name
• Every animal has one correct name International
Code of Zoological Nomenclature
• Genus begins with a Capital letter
• Entire name italicized or underlined
• Homo sapien or H. sapien
The three domains
• Arhaea- prokaryotic microbes live in extreme
environments, inhabit anaerobic environments
• Reflect the conditions of early life
• Archaea the most primitive life form
• Archaea give rise to two other domains
– Eubacteria- true bacteria and are prokaryotic
microorganisms
– Eukarya- include all eukaryotic organisms, diverged
more recently thus more closely related to archae
(protists, fungi, plants and animals)
Figure 7.2 (b)
Kingdom of Life
1969 R. Whittaker- five kingdom classification
System of classification that distinguished b/w
kingdoms according to
• cellular organization
• mode of nutrition
Figure 7.2 (a)
Monera- bacteria and cyanobacteria are
prokaryotic
• Protista- single or colonies of eukaryotic
cells (Ameoba, Paramecium)
• Plantae- eukaryotic, multicellular, and photosynthtic. Have
cell wall, and usually nonmotile
• Fungi-eukaryotic and multicellular. Have cell wall and
nonmotile. Mode of nutrition distiguishes fungi from plantfungi digest extracellularly and absorb the breakdown
products
• Animalia- eukaryotic and multicellular, usually feed by
ingesting other organisms, cell lack cell walls, and usually
motile
Text devoted to animals
• Except for Chapter 8 Animal like protists (Amoeba
and Paramecium)
• The inclusion of protozoa is part of a tradition
• Once considered a phylum (Protozoa) in the animal
kingdom