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Unikont Diversity II: Animals
I.
Functional and struct charact of animals
A. Nuutritional mode: heterotrophs
1. Diff from autotrophic plants and diff from heterotrophic fungi who
feed by absorption
2. Consumers: need producers for raw materials and E
3. Ingest food then digest inside body
B. Cell Structure
1. Multicellular euk : like plant and most fungi
2. Lack call walls, diff from plant and most fungi
3. Proteins external to cell membrane:
a. Connect cells to one another
b. provide struct support
c. Collagen: most abundant protein (not found in plant n fungi)
C. Cell specialization
1. Differentiated cells
a. Cells specialized to perform functions (ex: neurons)
2. Differentiated tissues
a. Group of cells with a common structure and act as functional
unit (ex: epithelium)
3. Differentiated organs
a. Specialized structure made up of tissues (ex: kidneys)
b. Adapted to perform a specific function of group of functions
4. Muscles and nerve tissue
a. Ability to move and conduct nerve impulses
b. Unique, defining characteristic
c. Diff from plants and fungi
D. Reproduction n development
1. Reproduction
a. Usually sexual with diploid stage dominating life cycle
b. Meiosis produces haploid sperm and egg
c. Fertilization small flagellated sperm fertilizes larger,
nonmotlile egg  zygote (n)
2. Devlpemt: early/late
a. Early embryonic development:
i.
Cleavage: zygote undergo series of mitotic divisions,
no cell growth between div
ii.
Blastula is a hollow ball of cells with inner cavity
called blastocoel
iii.
Gastrulation is embryo folds inwards expands and fills
blastocoel
i. Endoderm inner layer
ii. Ectoderm outer layer
iii. Archenteron is pouched formed by gastrulation
b. Later develop
i.
II.
Directly into adults: some animals do
i. Larval stage: most animals have at least one
larva form that is sexually immature form of
animal
ii. Morphologically different from adult
iii. May ear diff food than adult
iv. Live in diff habitat than adult
ii.
Juvie stage
i. Metamorphosis or larva
ii. Not sexually mature
iii. Resembles adult
3. Regulation of devlpmt
a. Development is regulated by gene expression
b. Homeobox genes are code for proteins that regulate expre
of devlpmetal genes
i.
Ex: Hox genes that regulate body form
c. Origin of multicellulat animals
i.
Morphological and molec evidence: protists called
choanoflagellates are closest relatives to animals:
sister taxa
ii.
Common ancestor may have resembled chono.flage.
iii.
Metazoan= animal kingdom – monophyletic group
Animals are characterized by “body plans”
A. Body plan: set of morphological and developmental traits. Used to
compare and categorize animals. Represent key steps in evo of animals.
1. PORIFERA (SPONGES) no defined tissues and organs
2. EUMETAZOA (TRUE ANIMALS) no defined tissues and organs
B. Symmetry: arrangement of body structures in relation to axis of body
1. Radial: body is wheel or cylinder. Multiple planes that divide into
mirror image. Many are sessile (live attached to a substrate) or
planktonic, which drift or swim weakly.
2. Bilateral: body can be dived only 1 plane through midlione,
which makes right and left halves mirror images
a. Due to cephalization, development of a head region (CNS)
b. Coordinate complex movements: crawling, flying, swimming
i.
Dorsal: back/top
ii.
Ventral: bottom/underside
iii.
Anterior: front/head
iv.
Posteriror: back/tail
v.
Left/ right
3. Asymmetry: no symmetry at all
C. Embryonic tissues development
1. Suring embryonic devlmpt embryo of all eumetazoans becomes
layered.
a. Germ layers: concentric layers of embryonic tissue
i.
Ectoderm: outer covering and nervous system
ii.
Endoderm: digestive tubes and dig organs
iii.
Mesoderm: other body strcuters
b. Diploblastic organism: only 2 layers ectoderm and endoderm
c. Triploblastic organism: all 3 layers, all bilateral
D. Body cavities
1. Most triploblastic animals have a body cavity
a. Coelom: true body cavity
i.
Fluid filled space btwn body wall and digestive tube
ii.
Tube within a tube body plan
iii.
Only in triploplastic animals
2. Aceolomates
a. No coelom
b. Triploblastic
c. Solid body
d. No fluid filled body cavity
3. Pseudocoelomate
a. Pseudocoelom
b. Body cavity formed from endoderm and mesoderm
c. Not completely lined with mesoderm
4. Coelomate
a. True coelom
b. Body cavity completely lined with mesoderm
5. Advantages of having a body cavity
a. Serves as a hydrostatic skeleton. Fluid under pressure,
gives movement
b. Mechanism for circulating meterials through body
i.
No longer need to be flat, gets around surface area to
volume problems
ii.
Skfj
iii.
Skdj
E. Developmental modes: protosome and deuterostome
1. Cleavage: succession of mitotic cell divisions by zygote
a. Protostomes: cleavage is
i.
Spiral: planes of cell division are diagonal to vertical
axis of embryo
ii.
Determinate: developmental fate of each embryonic
cell is set very early. If cell is removed, adult lacks
part
b. Deuterostomes: cleavage is
i.
Radial: planes are parallel or perpendicular to vertical
axis of embryo
ii.
Indeterminate: each cell retains capcity to develop
into a complete embryo (possible twins)
2. Coelom formation: during gastrulation, embryo’s developing
digestive tube initially forms as a blind pouch  archenteron
III.
a. Protostomes: as archenteron forms, solid masses of
mesoderm split and form coelom
b. Deuterostomes: mesoderm budes from wall of archenteron and
its cavity bcomes a coelom
3. Fate of blastopore: during early development embryo consists of
ball of cells and dsdskdj
a. Protostomes:sjfks
b. Deutrostomes: sjkfh
Diversification of animals
A. Cambrian explosion
1. Wave of animal diversification
2. Many diff animal body plans in short time
3. 1st fossils of large animals with hard mineralized skeletons
4. Some survived and some went extinct
B. Extant Phyla: phyla with members alive today
1. Kingdom Animalia: 1.3 million known species, estimated 10-20
million spp