First Animals Soft bodies so trace fossils only Sponges Jelly fish Worms Late Proterozoic
Time Line of Animal Evolution 1st Fossil evidence of animals 570 mya = Proterozoic Eon Massive adaptive radiation of animals called the Cambrian Explosion signaled the start of the Phanerozoic Eon Cambrian Explosion due to increased oxygen for aerobic respiration more energy = larger more mobile animals move into new areas and adapt
Phanerozoic begins with Cambrian Explosion
Evolution of Animals Some type of Protist mutated to become multicellular Multicellular organisms start as a single cell (zygote) and grow into organisms with groups of specialized cells performing different functions All animals are multicellular
Proterospongia = Protist & common ancestor to all animals?
Proterospongia: Colonial, Unicellular Protists
Sponge collar cells
Phylum Porifera Sponges Only 3 types of cells Collar cells Amoebocytes Epidermis cells (protective outer layer of cells) No tissues Cells held together by jelly like substance Skeleton make of proteins Asymetrical
Origin of sponges http://shapeoflife.org/video/sponges-origins
Sponges are sessile filter feaders http://shapeoflife.org/video/sponges-filter-feeding-made-visible http://shapeoflife.org/video/sponge-animation-wild-ride-through-sponge
Intracellular digestion (like protists) Collar cells take in food by endocytosis Food digested in food vacuoles Some food passed to amoebocytes Amoebocytes carry food around sponge body. (circulaton)
All other Animals have True Tissues & symmetry
Phylum Cnidaria Have stinging cells = cnidocytes Have tentacles First predators..First muscle-like cells (movement) Radial symmetry = sit and wait predator 1st nervous system = nerve net & eye spots
Digestion & Circulation Have gastrovascular cavity for digestion & circulation 1st extra cellular digestion – cells lining GVC secrete digestive enzymes Evolutionary advantage = can eat larger food Cilia push digested food around the GVC GVC branches into all tentacles: comes near all cells
Prey capture https://www.youtube.com/watch?v=RYVHK2vM1_Y
Jellyfish Reproduction Moon jellies https://vimeo.com/40232821 https://www.youtube.com/watch?v=ct9KyLmnu0I Hydra eating https://www.youtube.com/watch?v=MpSPdeTN74I
All other animals have Bilateral symmetry
Flatworms had it FIRST!! Bilateral symmetry Directional motion = 1st mobile predator Cephalization – development of a head Ganglia: bundle of nerve cells make up a pre-brain Nerves concentrated at ‘head end’ since sensory cells were concentrated at that end Sensory nerves formed bundles = ganglion Eyespots detect light, Auricles detect chemicals ‘smell’ 2 nerve cords transmit info to rest of body Flatworms had it FIRST!!
Evolution of Bilateral Symmetry https://vimeo.com/37282961
Flatworm primitive Traits Central mouth and GVC Motion with cilia
Free-living Flatworms = Class Turbellaria Marine Fresh-water
Flukes = Class Trematoda Parasites of blood and liver
Swimmer’s Itch =Schistosoma
Tape Worms = Class Cestoda
Human Tape Worm Sources =Under cooked Prevention Beef (N. America) Pork(S. America) Fish (Asia) Prevention Cook your meat!!!
Bilateral symmetry terms Dorsal : Back Ventral: Belly Anterior: head Posterior: tail
Embryo Development All Animals can do Sexual Reproduction All make eggs and sperm All start out as a single celled zygote ALL Zygotes grow into a hollow ball of cells called a blastula Blastula gets indented forming a gastrula
ALL Gastrulas develop at least 2 tissue layers endoderm and ectoderm (diploblastic) Some develop 3 layers endo, ecto and mesoderm (triploblastic)
All Animals more advanced that flatworms have a body cavity Provides room for organs to develop Body Cavities are called coeloms
Types of body cavity (coelom) Acoelomate Pseudocoelomate Coelomate
Round Worms = Phylum Nematoda 1st Animal with a body cavity =pseudocoelom Fake body cavity – just a space between layers.
Advantage to body cavity = space to grow specialized organs
Nematodes https://www.youtube.com/watch?v=dYPF5dmT__o First Animal with Alimentary Canal …. one way digestive tract mouth anus Advantages…. Can eat second meal before the first is fully digested Can specialize different segments of digestive tube = more efficient
Rotifers https://www.youtube.com/watch?v=YF8OJt_pujc
Gastrulation Formation of gastrula. Indentation creates opening called blastopore Blastopore either becomes mouth or anus Protostome = blastopore becomes mouth Deuterostome = blastopore becomes anus
Ascaris…………………………… One of the most common parasite of humans Up to 64% of people in some S.eastern states Eggs injested on Vegetables or from Soil
Heartworm Larva in Blood