intro to animal diversity chapter 32. slide 2 of 17 animalia – general notes 1.3 million species ...
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Intro to Animal Diversity
Chapter 32
Slide 2 of 17
Animalia – General Notes
1.3 million species 300K plant species 1.5 million fungi >10 million bacteria
Animals ARE heterotrophs Plantae? Fungi? Protista?
Animals are multicellular Plantae? Fungi? Protista? Bacteria?
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Animalia – General (Page 2)
Unique in the possession of muscular and nervous tissue
Lack cell walls Held together by structural proteins such as collagen Plants? Fungi? Bacteria? Protista?
Most reproduce sexually
Diploid stage is dominant in most
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Fertilization Zygote (Mitosis) Cleavage Blastula
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Embryology Notes
Cleavage – rapid series of mitotic divisions w/o cell growth in between What part(s) of the cell cycle would be proportionally
reduced during cleavage? Extended?
Blastula – Hollow ball of cells Cavity is called blastocoel
Gastrula – blastula gets “punched in” Embryonic tissue layers form from gastrulation Product of gastrulation called archenteron Blastophore is the opening of the archenteron
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2 Quick Things
Some animals have a larval stage Immature, distinct form Undergoes metamorphosis to
become adult form
Hox genes Common in animals Genes that play an important role
in development
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Animal Body Plans
There are 3 main types of animal body plans:
No symmetry Sponges
Radial symmetry Jellyfish and many primitive animals Central axis, and any cut through the axis results in
mirror images
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Bilateral Symmetry
Most amphibians, reptiles, birds, and mammals
Produces a right and left sides that are mirror images of each other
Usually produces dorsal and ventral sides
Associated with cephalization Anterior (head) end Posterior (tail) end Concentration of sensory equipment at one end
Usually anterior end
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Coelomate True coelom Fluid-filled body cavity between digestive tract & outer body wall True compartmentalization
Pseudocoelomate Triploblastic animals -- 3 tissue layers Cavity formed from mesoderm + endoderm
Acoelomate No cavity between alimentary canal and outer body wall
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Germ Layers
Give rise to the tissues and organs of the animal embryo
Ectoderm is the germ layer covering the embryo’s surface
Endoderm is the innermost germ layer and lines the developing digestive tube, called the archenteron
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Germ Layers
Diploblastic animals have ectoderm and endoderm
Triploblastic animals also have an intervening mesoderm layer; these include all bilaterians
A pseudocoelom is a body cavity derived from the mesoderm and endoderm
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Why a body cavity (coelom)?
The separation between body wall and digestive tract have advantages Cushion suspended organs
From blunt force and other sources of physical trauma Increased structural support
Skeletal structure or hydrostatic skeleton Internal organs grow and move independently
Greater specialization = more advanced
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Coelom Formation
In protostome development, the splitting of solid masses of mesoderm forms the coelom
In deuterostome development, the mesoderm buds from the wall of the archenteron to form the coelom
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Fate of the Blastophore
The blastopore forms during gastrulation and connects the archenteron to the exterior of the gastrula
In protostome development, the blastopore becomes the mouth
In deuterostome development, the blastopore becomes the anus
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