INVERTEBRATES Characteristics of Animals Invertebrates Eukaryotic Heterotrophic Multicellular
INVERTEBRATES
Characteristics of Animals (Invertebrates) • • • Eukaryotic Heterotrophic Multi-cellular No backbone (invertebrates only) Reproduce sexually and/or asexually
Phylum Porifera • “Pore-bearer” • Ex. Sponges • No tissues or organ systems
Porifera Systems • Asymmetrical • Mechanism for digestion, excretion, respiration, and circulation- movement of water through body • Reproductionsexual: egg/sperm asexual: budding or gemmules
Phylum Cnidaria • “Nettle” or “Stinger” • Ex. Hydras, Jellyfish, Sea anemones, Corals • Cells organized into tissues
Cnidarian Life Cycle • Two different stages of life cycle: – Polyp: usually sessile, mouth points up – Medusa: motile, mouth points down • Radial Symmetry
Cnidarian Systems • Digestion- stings prey, in through mouth, into gastrovascular cavity • Respiration, Circulation, Excretion. Diffusion through body • Nervous system- nerve net, special cells
Cnidarian Systems cont’d • Reproduction– Sexual: external fertilization of eggs – Asexual: budding
Worms- 3 Phyla • Phylum Platyhelminthes • Ex. Flatworms (planarians, flukes, tapeworms)
Worms- Platyhelminthes • Bilateral symmetry • Tissue layersectoderm, mesoderm, endoderm • Digestion- mouth, gastrovascular cavity
Platyhelminthes Systems • Respiration, Circulation, and Excreation- rely on diffusion through body • Nervous- ganglia, nerve cords, eyespots • Reproduction– Sexual: hermaphrodites – Asexual: fission
Worms- Nematoda • • Ex. Roundworms Bilateral symmetry Tissue layers Digestion- mouth and anus • Respiration, Circulation, Excretiondiffusion
Nematoda Systems cont’d • Nervous- several ganglia, nerves • Reproduction – Sexual: internal fertilization of egg
Worms- Annelida • Phylum Annelida • Ex. “Segmented” worms: earthworms, leeches, bristleworms • Bilateral symmetry • Tissue layers
Annelida Systems • Digestion- mouth and anus, pharynx • Circulation- closed system (blood contained in vessels) • Respiration- some gills, skin • Excretion- Nephridia, anus
Annelida Systems cont’d • Nervous- brain and nerve cords • Reproduction– Sexual: (most), separate sexes, hermaphrodites
Phylum Mollusca • Mollusks • Ex. Gastropods (snails), Bivalves (clams), Cephalopods (squid) • Internal or external shell • Bilateral symmetry • Tissue layers
Mollusk Systems • Digestion: Variety, mouth and anus • Respiration- gills or skin • Circulation- open system (except squid/octopi- closed) • Excretion-Nephridia
Mollusk Systems cont’d • Nervous- small ganglia, nerve cords brains • Reproduction– Sexual: internal/external fertilization
Phylum Echinodermata • Echinoderms- “Spiny skin” • Ex. Sea Stars, Sea Urchins, Sand Dollars • Internal skeleton • Water vascular system (tube feet) • Radial symmetry
Echinoderm Systems • Digestion- pushes out stomach through mouth, digests prey with enzymes • Respiration, Circulation- water vascular system • Excretion- water vascular system and anus
Echinoderm Systems cont’d • Nervous System: Nerve ring, sensory cells • Reproduction: external fertilization, most are separate sexes
Phylum Arthropoda • Arthropods- “Jointed foot” • Ex. Insects, crustaceans, spiders • Segmented body, exoskeleton, jointed appendages
Arthropod Systems • Respiration- tracheal tubes & spiracles, book lungs, gills • Circulation- open circulatory system • Excretion- Malpighian tubules or diffusion
Arthropod Systems cont’d • Nervous system. Brain, nerve cord, ganglia, sense organs • Reproduction- Internal fertilization, some (aquatic) external – Growth requires molting
Phylum Chordata • Characteristics: – Notochord (stiff flexible rod) – Nerve cord (hollow cord) – Gill slits – Post-anal tail • Two invertebrate subphyla: – Urochordata: tunicates – Cephalochordata: lancelets
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