Introduction to Animal Phyla

1. Introduction to Animal Phyla

2. Phyla Calcarea and Silicea • Sponges used to be classified in one Phylum = Porifera Pore-bearing • All aquatic • Have pores (ostia) that water flows through • Vary in size and shape – radial or asymmetrical

3. Cellular level of organization – no tissues • Multicellular: body a loose aggregation of cells • Intracellular digestion • Excretion and respiration by diffusion • Sessile adults • Asexual reproduction by buds or gemmules • Sexual reproduction – eggs and sperm • Free-swimming larvae

4. Phylum Cnidaria nettles • Includes: hydra, jellyfish, coral, sea anemones • All aquatic • Radial symmetry • Two body forms • Polyp: sessile (cannot move) • Medusa: free swimming • Tentacles with cnidocytes that contain stinging organelles called nematocytes

5. Diploblastic – two germ layers (endo- and ectoderm) with mesoglea • Gastrovascular cavity; extracellular digestion • Nerve net and primitive muscular system • Asexual reproduction by budding • Sexual forms either monoecious or dioecious – planula larva

6. Phylum Platyhelminthes flat-worms • Cell-tissue level of organization – most systems incomplete or lacking • Body flattened dorsoventrally • Bilateral symmetry • Classes Monogenea Trematoda and Cestoda are entirely parasitic • Class Tubellaria – free-living

7. Triploblastic – three germ layers • Acoelomate – no body cavity between the mesoderm and endoderm • Sexual reproduction by gametes – most forms monoecious (separate sexes) • No asexual reproduction • Complex life cycles with multiple hosts in parasitic forms

8. Phylum Nematoda Thread • Roundworms • Organ-system level of organization • Body round slender tubelike, tapered at both ends • Bilateral symmetry • Mostly free-living in soil or water; some parasitic forms (Ascaris)

9. Triploblastic – three germ layers • Pseudocoelomate – body cavity in between the mesoderm and endoderm • Body covered with a secreted, flexible, nonliving cuticle • Sexual reproduction with gametes – dioecious (male and female forms) • No asexual reproduction

10. Phylum Annelida Little rings • Segmented worms • Bilateral symmetry • Two major classes • Oligochaeta (earthworm) • Hirudinea • Includes leeches • Freshwater parasites • Secrete enzyme to prevent blood clotting in host

11. Mollusks • Phylum = Mollusca • Includes oysters, clams, snails and octopus • Three classes • Bivalvia – clams, two shells • Gastropoda – snails, single shell • Largest group • Cephalopoda – octopus, no shell • Most advanced • Mouth surrounded by tentacles

12. Echinoderms – spiny skin • Phylum Echinodermata includes starfish, sea urchins, sea cucumbers and sand dollars • Have internal skeletons that consists of calcified plates embedded in body wall • Radial symmetry • Spiny projections on plates stick through skin. • Have an oral and aboral surface

13. Phylum: Arthropoda • Most successful and abundant phylum of animals • 1 million known species (400,000 plants, 200,000 all other animals)

14. 5 classes of arthropods • Crustacea – lobsters etc. • Chilopoda - centipedes • Diplopoda - millipedes • Arachnida - spiders • Insecta - bugs

15. Common Features of all Arthropods • Jointed legs • Exoskeletons made of protein and chitin (hard and lightweight but must molt) • Segmented, most have: • Head • Thorax • Abdomen • Well developed nervous system • Open circulatory system

16. Centipedes • Class: Chilopoda • Poison claws on first segment • Body segments have one pair of legs • Feed on insects

17. Millipedes • Class: Diplopoda • Body segments have two pairs of legs • No poison claws • Feed on decaying plants • May roll into ball or use “stink” glands when disturbed

18. Spiders, ticks, mites, scorpions • Class Arachnida • Most live on land and resemble insects • Book lungs for gas exchange • Some have spinnerets for spinning silk (web) • 8 legs

20. Insects are successful because: • Only invertebrate that can fly • Tremendous variation and adaptations for feeding and reproduction, such as: • Mouthparts • Body form • Legs • High rate of reproduction and a short life cycle • Small

21. Metamorphosis • Distinct changes as an animal develops from an egg to an adult • Incomplete (grasshoppers and crickets) eggs  nymphs  adult • Complete (moths, butterflies, beetles, bees) eggs  larva  pupa  adult

23. Entomology – the study of insects • Bad: • Billions of dollars in damage to crops • Transmit animal and plant diseases • Insecticide poisons the environment • Sting and bite • Good • Pollinate crops • Destroy harmful insects • Make honey and other products Economic Importance

24. Clam Dissection (pg 739) • Find the valve adductor muscles. To open the shell, you must CAREFULLY cut these muscles. • Once open – make two drawings • Internal anatomy • Draw before you cut it open • Label 10 items total.

25. Crayfish Dissection • External anatomy – draw and label ten items • To open crayfish you must remove the carapace: Most of the body organs are located in the cephalothorax, the abdomen is mostly muscle. Make cuts 1 cm on each side of the midline toward the eyes. Snip between the two cuts and remove the strip of carapace. • Internal anatomy – draw and label five to ten items • Look at any part of the crayfish with the dissection scope. Make a drawing and label what it is.

26. Grasshopper Dissection • External Anatomy – draw and label 10 items • To open grasshopper up: • Cut off the wings and legs. Carefully open the exoskeleton. • Internal Anatomy – draw and label 5 items, is it male or female? • Make third drawing using the dissection scope. Label what it is.