Animal Evolution Chpt. 32

Multicellular

Multicellular Heterotrophic digest within body

MulticellularHeterotrophic Eukaryotic, no cell wall

MulticellularHeterotrophic Specialized cells

MulticellularHeterotrophic Eukaryotic, no cell wall Specialized cells Dominant diploid stage, sexual reproduction

Most, capable of locomotion at some point in lifetime.

Most capable of locomotion Most have nerve cells and muscle cells -> respond & move

Large nonmotile egg (n) + small flagellated sperm (n) = ZYGOTESexual Reproduction genetic diversity* genetic diversity * genetic diversity

mitotic divisions w/o cell growth (cleavage)

cleavage results in multicellular stage ---> blastula

end stage of cleavage

zygote to blastula - sea urchin

embryonic stem cells

human manipulation of embryonic stem cells

one end of the embryo folds inward - > Gastrulation- layers of embryonic tissue that w/ develop into body parts are formed

one end of the embryo folds inward - > Gastrulation- process during which three germ layers form

expands

fills the blastocoel (cavity)

produces layers of tissue

Gastrulation- process during which three germ layers form

Gastrula

ectoderm

Ectoderm becomes: outer covering, nervous system

endoderm

Endoderm becomes: digestive tract

mesoderm

Mesoderm becomes: muscles, blood

Genes that direct development of major body parts in an animal … provide positional information Impact morphology of the organism Transformation of a zygote to an animal of specific form is controlled by:

Origin of animals from a flagellated protist??

Parazoa -

Eumetazoa -

Parazoa - no tissues

Parazoa - no tissues (function like colonial protists)

porifera

Parazoa - Eumetazoa -

Eumetazoa - have true tissues

Eumetazoa true tissues arrangement of body symmetry

Eumetazoa true tissues Radial Symmetry arrangement of body structure

Receives stimuli from all directions all parts radiate from center

Eumetazoa true tissues Radial Symmetry Bilateral Symmetry arrangement of body structure

Cephalization

What is the evolutionary advantage of cephalization???

Eumetazoa Bilateral Symmetry Type of body cavity

Eumetazoa Bilateral Symmetry Acoelomate Type of body cavity

no body cavity between digestive cavity & outer body wall no tube outside of a tube

Eumetazoa Bilateral Symmetry Acoelomate Body cavity Type of body cavity

Have body cavity tube outside a tube

Body cavity, not completely lined with mesoderm

Have body cavity - mesoderm completely surrounds

Eumetazoa Bilateral Symmetry Coelomate

Body cavity, completely lined with mesoderm

Eumetazoa Bilateral Symmetry Pseudocoelomate Differences in pattern of early development

Eumetazoa Bilateral Symmetry Coelomate Differences in pattern of early development

Eumetazoa Bilateral Symmetry Coelomate Protosom es Differences in pattern of early development

Eumetazoa Bilateral Symmetry Coelomate Protosom es Deuterostom es Differences in pattern of early development

1. Pattern of cleavage

2. Coelom formation mesoderm stays connected forming coelom mesoderm splits forming coelom

2. Coelom formation Top view - deuterostomes

2. Coelom formation protostome

3. Blastopore “fate”