Life 103-Week 9 Notes
Life 103-Week 9 Notes Life 103
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This 7 page Class Notes was uploaded by Addy Carroll on Friday March 25, 2016. The Class Notes belongs to Life 103 at Colorado State University taught by Dr. Dale Lockwood and Dr. Tanya Dewey in Winter 2016. Since its upload, it has received 12 views. For similar materials see Biology of organisms-animals and plants in Biology at Colorado State University.
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Date Created: 03/25/16
Life 103 Notes *adapted from the lecture notes of Dr. Tanya Dewey* Animal Diversity and Evolution • Themes of Biology -Organization-structure and function, emergent properties, reductionism -Information-information is transferred between generations through genes (heredity) -Energy and Matter-all organisms require energy and matter, resources are often limited, look for trade-offs -Interactions-interactions are important at all levels of organization (cell to organisms to communities to the biosphere) -Evolution-nothing in biology makes sense except in the light of evolution • Themes in Animal Diversity -Trends in evolution -Tradeoffs and constraints -Different perspectives and ways of life • What is science? -Asking testable questions, formulated as hypotheses -Using evidence to answer those questions -Employing parsimony-simple explanations are preferred -Biology is a science -Science is a way of approaching problems that is applicable to nearly every aspect of your life • Eukaryan Diversity -Protists -Plants -Fungi -Animals • What are animals? -Metazoans -zoo or zoa=animals ~Ex.) Zoology • How well do we know animals? -<1million named species -Estimates up to 7.8 million total -86% of species on land yet to be discovered -91% of marine species yet to be discovered -Even in very common places, there are still many more species to be discovered -Most species on this planet are animals -70% of animals are insects -Animals have been around for a long time, but relative to every other species, they’re relatively recent • Ediacaran Origin -Animals evolved, including extant taxa and extinct forms -Only a few animal phyla evolved • Cambrian Explosion -Oldest fossils of half of extant animal phyla -Most major animal body plans evolve -Almost every other animal phyla that didn’t evolve in Ediacaran evolved in Cambrian • What are animals? =Metazoans -Multicellular -Ingestive heterotrophs ~Do not produce own food; take food into body and digest internally -Move under own volition at some point in life ~At some point they were motile -Lack cell walls, have structural proteins (extracellular matrix) -Unique, specialized cells: nerve and muscle (except sponges) ~Most animals have these cells, whereas they aren’t found in any other species -Sexual reproduction -2n (diploid) dominant -Flagellated sperm, non-motile egg -Most have larval stage -Cells are organized into tissues -Conserved genes control development (Hox genes) -Zygote undergoes cleavage, forms blastula, gastrulation • Eumetazoa=true tissues -Doesn’t include sponges because they don’t have true tissues -Metazoa includes sponges, but eumetazoa doesn’t • Themes in animal evolution (see textbook figure 32.11) -Origin of multicellularity -Origin of bilateral symmetry, cephalization, and the nervous system -Origin of embryonic tissue layers -Origin of a coelom -Origin of protostome and deuterostome development -Origin of segmentation • Origin of multicellularity -Choanoflagellates are the unicellular sister group to animals (see textbook figure 32.3) -Evolved at the origin of animals (Metazoa; includes sponges and all other animals) • Origin of bilateral symmetry, cephalization (formation of a head), and the nervous system -Types of symmetry ~Bilateral symmetry (Ex. Beetle) ~Radial symmetry (Ex. Coral polyp) ~No symmetry (Ex. Sponge) ~Pentaradial symmetry/pentamerism (echinoderms, except their larvae have bilateral symmetry) -Bilateral symmetry means you can have a head = cephalization ~Having a head gives the animal directionality (front and a back) ~Having a head gives the animal the ability to eat/be a predator -Concentrate sensory apparatus and nervous system at head -Evolved at the Bilateria origin (has bilateral symmetry if ancestor is Bilateria, Ctenophora and Cnidaria have radial symmetry, and sponges have no symmetry) -Genetic mechanisms responsible for bilateral symmetry and cephalization are shared (homologous) • Origin of embryonic tissue layers -Diploblastic=2 tissue layers (Endoderm and Ectoderm) -Triploblastic=3 tissue layers (Endoderm, Mesoderm, and Ectoderm) -Species with Bilateria ancestor are triploblastic, while Ctenophora and Cnidaria are diploblastic • Origin of a coelom -Animals are tubular-tubes within tubes -Coelom- a fluid-filled body cavity between the inner and outer tubes; disengages gut from outer layers, space for nutrients to move, forms basis of hydrostatic skeleton -3 body plans (see textbook figure 32.9) ~Acoelomate=no coelom ~Coelomate=has coelom ~Pseudocoelomate=false coelom (not a true coelom) -Pseudocoelomate has the space touching both the mesoderm and endoderm, while a true coelom only touches the mesoderm -Cannot say the coelomate evolved at a specific point of the tree because the body plans are randomly distributed ~Diploblastic and sponges don’t have coeloms ~Body plans scattered among Bilateria species • Origin of protostome and deuterostome development -“Stoma”=opening or mouth -Protostome-the mouth is formed before the anus ~”First mouth” -Deuterostome-the anus is formed before the mouth ~”Second mouth -The first opening in protostomes is the mouth, while the first opening in deuterostomes is the anus -Deuterostomes evolved at Deuterostomia -Protosomes, or “Spiralia,” evolved at Lophotrochozoa and Ecdysozoa • Origin of segmentation -Not all animal groups show segmentation -Common genes called Hox genes control segmentation -Suggesting flexible response through evolutionary history -Why segmentation? ~Permits specialization-genetic duplication releases copies to be modified for new purposes-look for this theme in vertebrate evolution Animal Taxa: Invertebrates I (Diversity) • Invertebrate Diversity (see textbook figure 33.3) -Morphological and molecular data are combined to understand relationships among animal phyla -Molecular (DNA) data has revolutionized our understanding • “Big 9” animal phyla -Porifera -Cnidaria -Platyhelminthes -Mollusca -Annelida -Nematoda -Arthropoda -Echinodermata -Chordata • *Porifera (sponges) -5,000-10,000 species -Filter feeding -No symmetry -Sessile -Mostly marine • Ctenophora (comb jellies) -100-150 species -Predatory -Radially symmetrical -Motile (via cilia) -Entirely marine • *Cnidaria (jellyfish, corals, anemones) -Over 10,000 species -Predatory or filter feeding -Radially symmetrical -Both motile and sessile -Mostly marine • Placozoa (“flat animals”) -1 to a few species -Detritivore -Radially symmetrical -Motile (via flagella) -Entirely marine • Acoela (acoel flatworms) -Approximately 400 species -Predatory -Bilaterally symmetrical -Motile (via cilia) -Mostly marine • Rotifera (wheel animals) -Filter feeding -Bilaterally symmetrical -Motile -Mostly freshwater • Acanthocephala (spiny headed worms) -1150 species -Parasitic -Bilaterally symmetrical -Motile -Parasitic (freshwater) • Cycliophora -1-2 species -Discovered in 1995, found on the mouthparts of lobsters -Parasitic or commensal -Symmetry is not clear -Motile -Marine • Gastrotricha (hairybacks) -790 species -Detritivores -Motile -Marine and freshwater • Gnathostomulida (jaw worms) -100 species -Detritivore -Motile (via cilia) -Marine • *Platyhelminthes (flatworms) -25,000 species -Predators or parasites -Motile -Moist habitats • Entoprocta (“anus inside”) -150 species -Filter feeding -Sessile and colonial -Mostly marine • *Mollusca (mollusks) -85,000 species -More varied forms than any other phylum -Predatory, filter feeding, detritivores -Both motile and sessile -Marine, freshwater, terrestrial • Sipunculida (peanut worms) -320 species -Filter feeding -Motile -Marine • Brachiopoda (lamp shells) -330 species -Filter feeding -Sessile -Marine • Phoronida (horseshoe worms) -25 species -Filter feeding -Sessile -Marine • Ectoprocta/Bryzoa (moss animals “anus outside”) -4,000 species -Filter feeding -Sessile -Mostly marine • Nemertea (ribbon worms) -1,800 species -Predatory and parasitic -Motile -Mostly marine, some freshwater and terrestrial • *Annelida (segmented worms) -22,000 species -Predatory, filter feeding, detritivores, sanguivores -Both motile and sessile -Marine, freshwater, terrestrial • Priapulida (penis worm) -16 species -Detritivore -Motile -Marine • Kinorhyncha (mud dragons) -Detritivore/predatory -Motile -Marina • Loricifera -120 species -Discovered in 1983 in anoxic, deep sea brine -No mitochondria -Feeding style unknown -Sessile -Marine • Nematomorpha (horsehair worms) -2,000 species -Parasitic -Motile -Freshwater or moist habitats • *Nematoda (roundworms) -15,000 species or up to 1 million -Half parasitic, half free living -Motile -Nearly all habitats and all elevations • Chaetognatha (arrow worms) -120 species -Predatory -Motile -Marine planktonic • Tardigrada (water bears) -1,150 species -Predatory -Motile -Moist habitats, extreme environments • Onychophora (velvet worms) -180 species -Predatory -Motile -Terrestrial • *Arthropoda (arthropods) -Many millions -Every feeding style imaginable -Motile -Marine, freshwater, terrestrial • What are the patterns you observe in the diversity of animal phyla? -Most phyla live in marine habitats, however, terrestrial phyla tend to have more overall diversity