Invertebrate Diversity

1. InvertebrateDiversity Comparison of Increasing Complexity

2. What is an invertebrate? Name some common invertebrates? Are snakes invertebrates?

3. Introductory Vocabulary Invertebrate – animal without a backbone Coelom – fluid-filled space between body wall and intestine Cephalization – sensory organs concentrated at the anterior end of the organism Sexual reproduction – gametes are produced and fuse to form unique diploid offspring Asexual reproduction – single parent produces offspring genetically identical to itself Hermaphrodite – animals with both ovaries and testes

4. Sessile – nonmotile; animal that doesn’t move on its own Open circulatory system – vessels empty into body spaces called sinuses Closed circulatory system – blood never leaves vessels as it flows through the body Compound eye – eye with many lenses; found in arthropods Notochord – stiff rod found in chordates that becomes the vertebral column in vertebrates Dorsal nerve cord – bundle of nervous tissue found in chordates that becomes the spinal cord in vertebrates Pharyngeal slits – openings in the pharynx found in chordates that give rise to many structures in vertebrates

5. Kingdom Animalia Invertebrate phyla: Porifera -sponges Cnidaria-sea anemones,coral and jelly fish Platyhelminthes-flatworms (planaria, flukes, tapeworms) Nematoda -roundworms

6. Mollusca-slugs, snails, “seashell animals”, octopii and squid Annelida – segmented worms (marine worms, earthworms & leeches) Arthropoda – insects, arachnids & crustaceans Echinodermata – starfish, sand dollars, sea urchins, & sea cucumbers

7. Porifera • Sponges • Multicellular; no true tissues; asymmetric; sessile • spongin- protein fibers for structure; spicules for skeleton • individual cells acting together as an organism • filter feeders using collar cells (choanocytes) & amoebocytes • Water enters pores and exits osculum • Asexual reproduction • fragmentation • sexual reproduction (hermaphroditic) • External fertilization

8. Cnideria • Radial symmetry; true tissues; sessile and/or motile • Cnidocytes - stinging barbs to capture prey • Tentacles to bring prey into gastrovascular cavity • Two body forms • Polyp – sessile with mouth dorsal • Medusa – motile with mouth ventral • Asexual reproduction - budding • Sexual reproduction - external fertilization resulting in planulae larvae Classes of cniderians: Hydrozoa – hydra, Obelia, & Portuguese man-of-war Scyphozoa – jellyfish Anthozoa – sea anemones & coral

9. Platyhelminthes - flatworms • bilateral symmetry; cephalization; acoelomate; organs • Nervous system: ganglia & nerve cords • Excretory system: flame cells • Digestive system: two-way digestive tract with common mouth/anus; gastrovascular cavity • Respiratory system: diffusion through epidermis • Circulatory system: none (diffusion) • Reproductive system: • Sexual – internal fertilization; hermaphroditic; lay eggs • Asexual - fragmentation

10. Class Trematoda - endoparasites OR ectoparasites - complex life cycle with more than one host - primitive or no digestive system Schistosoma – major public health threat; cause liver damage • Class Cestoda • Tapeworms • Parasites • Attach to intestinal wall of host with scolex • proglottids – segments packed with reproductive organs • absorb nutrition from host –don’t need digestive system Class Turbellaria - planaria - freeliving - one of few freshwater species “typical” flatworm

11. Phylum Nematoda - roundworms - pseudocoelomate - hydrostatic skeleton • one-way digestive system with separate mouth/anus • Respiration and circulation by diffusion • Have longitudinal muscles • Reproduction – sexual; complex life-cycle with multiple hosts • Most are free-living predators in the soil • Some are parasitic; hookworms, pinworms, Trichinella

12. Mollusca • Coelomate; bilateral symmetry; organs; exoskeleton (shell) • 3-part body plan: • Visceral mass – contains organs • Mantle – secretes shell • Foot – locomotion • Radula – for feeding • cephalization • Open circulatory system • One-way digestive system • Nephridia – excretory organs • Respiration – gills, mantle cavity, and/or diffusion across skin • Reproduce sexually; many hermaphroditic; form trochophore larvae • Classes of mollusks – based on body plan: • *Gastropoda – stomach-foot; snails and slugs • *Bivalvia – two-shells; clams, oysters, mussels • *Cephalopoda – head-foot; nautilus, squid, octopi, cuttlefish

13. ANNELIDA • Oligochaeta – earthworms • Hirudinea – leeches • Polychaeta – marine worms

14. Major characteristics of all annelids: • Segmentation – separated by septa; each segment has organs of each major system • Cephalization – including cerebral ganglia • Ventral nerve cord • Coelom – hydrostatic skeleton • Organ systems • Setae – bristles for movement • Parapodia – fleshy appendages for movement &/or respiration

15. Earthworms • Ecologically important scavengers • Two layers of muscle: longitudinal & circular • 5 hearts; closed circulatory system • Nephridia for excretion • Respiration through epidermis • Complex digestive system with mouth, pharynx, esophagus, crop, gizzard, intestine, and anus • Sexual reproduction; hermaphroditic; clitellum forms mucus cocoon to protect fertilized eggs

16. How are HUMANS separated into body segments? Remnants of segmentation are visible in the embryo as repeated blocks of tissue called somites and in the vertebral column

17. Arthropods • largest and most diverse phylum; includes insects, crustaceans, spiders • segmented bodies – head, thorax, & abdomen or cephalo-thorax & abdomen; segmentation apparent on abdomen • jointed appendages (3, 4 or 5 pairs of walking legs plus assorted other specialized appendages) • Respiration: spiracles into trachea; gills; book lungs • Excretion through Malpighian tubules • Incomplete or complete metamorphosis • exoskeleton of chitin *complex muscular system • ventral nerve cord & brain * open circulatory system • compound eyes * ecdysis (molting)

18. Millipedes – 2 pairs of legs per segment - herbivores or detritovores, but can be really smelly! - one pair of antennae Centipedes – 1 pair of legs per segment - predators with jaws - one pair of antennae

19. Insects – 3 body regions: head, thorax, abdomen - 3 pairs of legs attached to thorax - exoskeleton of chitin - jaws (mandibles)modified for particular feeding method - wings are extensions of the exoskeleton; 0, 1 or 2 pairs - 1 pair of antennae - compound eyes

20. Arachnids – spiders, scorpions, ticks, & mites • Chelicerae – mouthparts modified into pincers or fangs • Cephalothorax & abdomen • 4 pairs of walking legs • No antennae • Simple eyes • Spinnerets & silk glands in spiders • Book lungs in spiders • Predators that consume liquified food • Distantly related to horseshoe crabs tick mite

21. Crustaceans Ecologically important – copepods & krill are planktonic crustaceans that form the basis of many marine food chains Crabs, lobsters, shrimp, & crayfish are other well-known crustaceans called decapods – “10 feet” First pair of walking legs often modified into chelipeds (pincers) 2 pair of antennae Compound eyes Sexual reproduction Cephalothorax covered by carapace Small appendages on abdomen of of some called swimmerets Barnacles are sessile crustaceans Pill bugs (isopods) are terrestrial crustaceans with gills

22. ECHINODERMS • Only live in salt water (oceans) • Five-part radial symmetry in adults; larvae are bilaterally symmetrical • Hard, bumpy, spiny endoskeleton composed of ossicles • Water vascular system with 5 rows of tube feet that aid them in movement, gas exchange, food capture and waste excretion. • Skin gills increase respiratory surface area & function in excretion • Feeding in starfish involves everting stomach out of mouth, digesting prey outside of body, and then pulling the digested material into the body; other echinoderms tend to be filter feeds or detritivores • Ex: starfish, sand dollar, sea cucumber, sea urchin, sea cucumber, sea biscuit, brittle stars, sea lilies, sea daisies, sea pens, feather stars

23. Invertebrate Chordates 4 characteristics of all chordates: *Notochord *Dorsal hollow nerve cord *Pharyngeal gill slits *Postanal tail Invertebrate chordates include tunicates & lancelets; all other chordates are vertebrates tunicate lancelet