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How Many Kingdoms? Multicellular Animals MyxozoansProtozoans Tracheophytes Bryophytes True Fungi Slime Molds Red algae Brown Algae Green Algae Chrysophytes.

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Presentation on theme: "How Many Kingdoms? Multicellular Animals MyxozoansProtozoans Tracheophytes Bryophytes True Fungi Slime Molds Red algae Brown Algae Green Algae Chrysophytes."— Presentation transcript:

1 How Many Kingdoms? Multicellular Animals MyxozoansProtozoans Tracheophytes Bryophytes True Fungi Slime Molds Red algae Brown Algae Green Algae Chrysophytes Euglenoids Archezoans Archaebacteria Bacteria Original Cell Extant Extinct Long Time with Prokaryotes only

2 Animal Features Multicellular Eukaryotes Heterotrophic Ingestion Collagen Protein Connections Nerve and Muscle Tissues Diplontic (Gametic) Life History Gametes Oogamous with Flagellated Sperm Zygote to Blastula, perhaps Gastrulation Larval metamorphosis into Adult Ontogeny Recapitulating Phylogeny

3 Animals Domain Eukarya Kingdom Animalia Phylum Nematoda

4 Nematode Body Organization

5 Caenorhabditis elegans is a bacteriovorous soil nematode, feeds on E. coli in vitro, is a genetic model organism, its genome is sequenced. N=6 XX=hermaphrodite XO=male Life cycle: 3 days at 20°C vulva anus mouth embryo in shell of zygote protandrous

6 meiosis syngamy protandrous

7 Animals Domain Eukarya Kingdom Animalia Phylum Annelida

8 Lumbriculus variegatus : California mudworm This is an aquatic oligochaete annelid Mouth feeds in sediments Tail extends toward water surface for gas exchange Body walls nearly transparent for easy observation For example: may count pulses of blood in dorsal vessel

9 Lumbricus terrestris: Canadian nightcrawler or Earthworm mouth clitellum edge of ventral reproductive structures anus

10 The earthworm body is fundamentally segmented. Here is a typical segment: The segments near the head are specialized for other physiological functions. Each segment is filled with coelomic fluid, under some pressure, which provides stiffness.

11 Dermal: Gas Exchange Nervous: Sensory and Coordination Muscular: Movement Digestive: Food Intake Nutrient Absorption Reproductive: Male Female Circulatory: Gases, Nutrients, Wastes Excretory: Major Organ Systems in an Earthworm

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13 Characteristics More than 100 segments Segments separated by partitions that divide coelom Segments identical except when specialized and fused Anterior and posterior ends Cephalization specialized for burrowing Head contains sense organs Circular and longitudinal muscles 1 Mouth 2 Prostomium 3 Segment 4 Spermathecal openings 5 Female (oviduct) opening 6 Male (vas deferens) opening 7 Sperm groove 8 Papilla 9 Clitellum (saddle) 10 Paired setae (ventro-lateral) 11 Anus 12 Dorsal surface 13 Ventral surface

14 Movement Setae anchored during movement Circular muscles contract Hydrostatic pressure increases in anterior coelomic cavities Body elongates pushing head forward Anterior setae grip ground Longitudinal muscles contract--posterior pulled along Coelomic divisions allow simultaneous contraction and expansion of segments A External view B Section through segment 1 Coelom 2 Circular muscle 3 Cuticle 4 Intestine 5 Dorsal blood vessel 6 Typhlosole 7 Epidermis 8 Nephridium 9 Longitudinal muscle 10 Seta 11 Protractor muscle 12 Retractor muscle 13 Ventral nerve cord 14 Subneural vessel 15 Ventral vessel 16 Septum

15 1 Anus 2 Intestine 3 Cerebral ganglion 4 Prostomium 5 Mouth 6 Nerve collar 7 Segmental ganglion 8 Pharynx 9 Esophagus 10 Segmental nerve 11 Crop 12 Gizzard 13 Ventral nerve cord Nervous Sensitive to tough, light, moisture, chemicals, temperature, and vibrations Light receptors on head and tail--sense direction Most sense organs and nerves control muscle contractions in individual segments Pair of ganglia in each segment coordinate movement with adjacent segments Cerebral ganglion in head controls total body Ventral nerve cord connects brain with ganglia

16 Feeding Feed on organic matter in soil Digest organic matter Wastes and undigested soil eliminated as casting Loosens and aerates soil Digestion Soil sucked in by pharynx -> esophagus -> crop (storage) -> gizzard (grinds soil releasing organic matter) -> intestine (nutrients absorbed) 1 Anus 2 Intestine 3 Cerebral ganglion 4 Prostomium 5 Mouth 6 Nerve collar 7 Segmental ganglion 8 Pharynx 9 Esophagus 10 Segmental nerve 11 Crop 12 Gizzard 13 Ventral nerve cord

17 Circulation Transport oxygen, nutrients, and wastes Flow of blood toward posterior via ventral blood vessel Flow of blood toward anterior via dorsal blood vessel 5 pair of aortic arches link vessels near anterior Smaller vessels branch into segments Contraction of ventral vessel and aortic arches forces blood through body 1 Anus 2 Dorso-subneural vessel 3 Intestine 4 Dorsal vessel 5 Hearts (aortic arches) 6 Mouth 7 Ventral vessel 8 Subneural vessel

18 Gas Exchange Lack gills or lungs--oxygen and carbon dioxide diffuse across skin Requires moist skin, thin cuticle, mucus secretion…limits habitat! Excretion Elimination of nitrogen wastes Long tubules (nephridia) excrete wastes Coelomic fluid enters nephridium through ciliated funnel opening Some water reabsorbed by blood Remaining fluid excreted through ventral pores A External view B Excretory system (nephridium) C-D Reproductive system C Lateral view D Dorsal view 1 Nephrostome 2 Septum 3 Ciliated tube 4 Bladder 5 Nephridiopore 6 Body wall

19 Reproduction Hermaphrodites--cannot self fertilize Worms join head to tail Form mucus coat around bodies--each inject sperm into mucus Sperm move to seminal receptacle Eggs move through oviducts to female genital pore Clitellum secretes mucus and chitinous sheath Worm wiggles to slip off sheath Eggs and sperm join A External view B Excretory system (nephridium) C-D Reproductive system C Lateral view D Dorsal view 1 Nephrostome 2 Septum 3 Ciliated tube 4 Bladder 5 Nephridiopore 6 Body wall 7 Seminal vesicle 8 Testis 9 Egg sac 10 Male opening 11 Female opening 12 Oviduct 13 Ovary 14 Sperm duct (vas deferens) 15 Opening to sperm-receiving sac 16 Sperm-receiving sac (spermatheca)

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21 Animals probably evolved from a flagellated protist similar to the choanoflagellates flagellum collar cell body One step in this evolution is to become colonial. Here are the choanocytes of one of the simplest of sponges. Basically the most primitive animals. Of course the other required step is to eliminate the chloroplasts of the choanoflagellate (Chrysophyta!).

22 Sponge, Cnidarian Ectoderm Endoderm spongocoel Acoelomate Mesoderm 2-layered Planarian 3-layered gastrovascular cavity Nematode pseudocoelom digestive tract Pseudocoelomate Annelid Coelomate coelom Evolution of Body Organization

23 zygote cleavage blastula Development or Evolution? 2-layered acoelomate body plan

24 Cnidarians Protostome Phyla Deuterostome Phyla (except vertebrates) Origin of Mesoderm Platyhelminthes Nematoda Annelida Mollusca Arthropoda Echinodermata Hemichordata Chordata mouth anus blastocoel blastopore mouth archenteron

25 The Animal Clade Chordata Ancestral Choanoflagellate Cnidaria Hemichordata Echinodermata Extant deuterostomia Arthropoda Annelida Mollusca protostomia coelomates Nematoda Rotifera pseudo- coelomates Platyhelminthes acoelomates radiata bilateria eumetazoa (true tissues) Porifera parazoa loss of chloroplast, colonial organization This cladogram omits several smaller animal phyla!


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