Download Chapter 32: Intro to Animal Diversity Kingdom Animalia • Multi

Chapter 32: Intro to Animal Diversity
Kingdom Animalia
 Multi-cellular eukaryotes
 Heterotrophic – ingest food
 Structure – no cell walls (use structural proteins in ECM)
o Collagen – most abundant
 Muscle & nerve cells (& tissues)
 Mostly sexual repro. w/ diploid dom.
 35 phyla (9 majors)
3 Eons
 Archaean (Origin-2.5 bya)
o Prokaryotes
 Proterozoic (2.5 bya-540 mya)
o Eukaryotes
o Early soft-bodied invertebrates
 Phanerozoic (540 mya-present)
o Complex life forms
Animal History
 Proterozoic Eon
o 2.5 bya-540 mya
o Ediacaran biota – earliest animals in fossil record
 From Ediacaran Period
 565 to 550 mya
 3 Eras in Phanerozoic Eon
o Paleozoic Era
 Cambrian (Period) Explosion (535-525 mya) – earliest fossils of many major animal phyla
 Arthropods, Chordates, Echinoderms
 Predator-prey relationships? – drove natural selection
 Rise in atmospheric oxygen? – allowed higher metabolism & size
 Evolution of Hox gene complex? – developmental flexibility
 Ordovician Period (460 mya) – animals land
 Millipede & centipede (-like)
 Devonian Period (360 mya) – tetrapods land
 Lobe-finned fish…
o Amphibians
o Amniotes – Mammals & Reptiles (& Aves/Birds)
 Carboniferous Period (350-300 mya) – amphibians dominate
 Fern forests – today’s coal
 Permian Period (299-251 mya) – radiation of reptiles
 Most modern insect groups
 Permian Mass Extinction (volcanism)
o Mesozoic Era – Age of Reptiles (Triassic, Jurassic, & Cretaceous Periods)
 251-65.5 mya
 Corals appear – create huge # of niches & habitat
 Dinosaurs dominate
 Reptiles enter water & air
 Mammals & angiosperms appear
 Cretaceous Extinction (asteroid)
o Cenozoic Era – Age of Mammals
 65.5 mya – Present
 Mammals – adaptive radiation of niches left by reptiles
 Large herbivores & predators
 Pollinating insects & birds
 Human lineage diverged 6-7 mya (species ~195,000 yrs old)
Reproduction & Development
 Fertilization – small, flagellated sperm (n) + large non-motile egg (n)
 Zygote – single 2n cell
 Cleavage – rapid mitotic division (1-2n forms 2-2n) w/o cell growth
 Blastula – ball of cells w/…
o Blastocoel – fluid-filled cavity
 Gastrulation
o Blastula folds inwards as cells migrate to fill blastocoel
o Gastrula formed
 Blastopore – opening (hole)
 Archenteron – primitive gut
 Germ Layers – embryonic tissue
 Tissues
o Collection of specialized cells isolated from other tissues by membranous layers
o Tissues (& organs) made from 3 embryonic germ layers
o Germ Layers
 Ectoderm – outermost layer; becomes Skin & nervous system
 Endoderm – innermost layer lining archenteron; becomes Digestive tract lining
 Mesoderm – middle tissue; becomes Muscle, blood, bones
 Hox Genes
o In all animals
o Regulate development of body
 Determine basic structure & orientation of an animal
o Hox proteins are transcription factors
 Bind to certain DNA locations to activate or repress DNA
 Body Symmetry
o No symmetry (e.g. sponge)
o Radial symmetry
 Sessile or planktonic (floating); e.g. Sea Anemone
o Bilateral symmetry
 Move around; e.g. Mammals
 Body Directions
 Right & Left sides
 Dorsal (top) & Ventral (bottom)
 Anterior (head) & Posterior (tail)
 Cephalization – sensory organs moved to one end (i.e.development of a head)
 Body Cavities
o Fluid- or air-filled space b/w digestive tract & outer body wall
 Cushion for organs
 Organs can grow & move w/o changing skin
o 3 types…
 Coelom – Made only of mesoderm (Coelomate animals)
 Pseudocoelom – made of mesoderm & endoderm (Pseudocoelomate animals)
 Acoelom – no body cavity (Acoelomate animals)
 Development Modes
o Deuterostome
 Cleavage is radial & indeterminate
 Early cells can make a complete embryo (fraternal twins)
 Coelom made as archenteron wall (mesoderm) folds to form coelom
 Blastopore becomes anus (2nd = mouth)
o Protostome
 Cleavage is spiral & determinate
 Take away a cell = missing body parts
 Coelom made as solid masses of mesoderm split off & form coelom
 Blastopore becomes mouth (1st = mouth)