Introduction to Invertebrates Chapter 29 Mader: Biology 8th Ed.

Cnidarians and Comb Jellies Hydra Obelia Bilateral Symmetry Flatworms Outline Evolution of Animals Sponges Cnidarians and Comb Jellies Hydra Obelia Bilateral Symmetry Flatworms Roundworms Mader: Biology 8th Ed.

Classification Criteria Level of organization Cellular, tissue, organ Evolution of Animals All animals are multicellular heterotrophic organisms that must take in preformed food. Classification Criteria Level of organization Cellular, tissue, organ Body Plan Sac, tube-within-a-tube Segmentation Segmentation leads to specialization. Mader: Biology 8th Ed.

Radial - Two identical halves. Evolution of Animals Symmetry Radial - Two identical halves. Bilateral - Definite right and left halves. Type of Coelom Pseudocoelom Coelom Protostome - First embryonic opening becomes the mouth. Dueterostome - Second embryonic opening becomes the mouth. Mader: Biology 8th Ed.

Only level of animal to have cellular organization. Multicellularity Sponges Only level of animal to have cellular organization. Saclike bodies perforated by many pores. Beating of flagella produces water currents that flow through pores into central cavity and out osculum. Sessile filter feeders. Asexual reproduction by fragmentation or budding. Mader: Biology 8th Ed.

Simple Sponge Anatomy Mader: Biology 8th Ed.

Total of three possible germ layers. Ectoderm, endoderm, and mesoderm True Tissue Layers Total of three possible germ layers. Ectoderm, endoderm, and mesoderm Animals in phlyum Ctenophora (comb jellies) and in phylum Cnidaria (cnidarians) develop only ectoderm and endoderm. Diploblasts Radially symmetrical Mader: Biology 8th Ed.

Cnidarian and Comb Jelly Mader: Biology 8th Ed.

Small, transparent, and often luminescent. Comb Jellies Small, transparent, and often luminescent. Most of body composed of mesoglea. Largest animals propelled by beating of cilia. Capture prey with tentacles. Mader: Biology 8th Ed.

Tubular animals that most often reside in shallow marine waters. Cnidarians Tubular animals that most often reside in shallow marine waters. Polyp and medusa body forms. Specialized stinging cells (cnidocytes). Fluid-filled capsule, nematocyst. Two-layered body sac. Outer layer - Protective epidermis. Inner layer - Gastrovascular cavity. Nerve net found throughout body. Mader: Biology 8th Ed.

Cnidarian Diversity Mader: Biology 8th Ed.

Freshwater cnidarians. Hydra Freshwater cnidarians. Small tubular poly body about one-quarter inch in length. Gastrovascular cavity is central cavity. Tentacles can respond to stimuli. Can reproduce sexually and asexually. Mader: Biology 8th Ed.

Hydra Mader: Biology 8th Ed.

A colony of polyps enclosed by a hard, chitinous covering. Obelia A colony of polyps enclosed by a hard, chitinous covering. Feeding polyps Extend beyond covering Have nematocyst-bearing tentacles. Reproductive polyps Budding of new polyps. Also has sexual reproduction (medusae) stage. Mader: Biology 8th Ed.

Obelia Mader: Biology 8th Ed.

Ribbon worms (phylum Nemertea) Have distinctive proboscis Bilateral Symmetry Ribbon worms (phylum Nemertea) Have distinctive proboscis Flatworms (phylum Platyhelminthes) Majority are parasitic Organ-level organization No specialized circulatory or respiratory structures. Have undergone cephalization Ladder-type nervous system Mader: Biology 8th Ed.

Free-living Flatworms Planarians (genus Dugesia) Live in freshwater habitats. Head is bluntly arrow shaped. Auricles function as sense organs. Two light-sensitive eye spots. Three kinds of muscle layers: Outer circular layer Inner longitudinal layer Diagonal layer Mader: Biology 8th Ed.

Excretory organ functions in osmotic regulation and water excretion. Planarians Excretory organ functions in osmotic regulation and water excretion. Can reproduce asexually Hermaphroditic Practice cross-fertilization Mader: Biology 8th Ed.

Mader: Biology 8th Ed.

Parasitic flatworms are flukes (trematodes) and tapeworms (cestodes). Well-developed nerves and gastrovascular cavity are unnecessary. Flukes Usually named for type of vertebrate organ they inhabit. Reproductive system well developed. Usually hermaphroditic. Mader: Biology 8th Ed.

Transmission of Schistosomiasis Mader: Biology 8th Ed.

Behind head region, scolex, a long series of proglottids are found. Parasitic Flatworms Tapeworms Have anterior region with modifications for attachment to intestinal wall of host. Behind head region, scolex, a long series of proglottids are found. Segments each containing a full set of both male and female sex organs. Complicated life cycles. Mader: Biology 8th Ed.

Life Cycle of Taenia Mader: Biology 8th Ed.

Roundworms (phylum Nematoda) Nonsegmented, generally colorless worms. Pseudocoelom Pseudocoelom is a false body cavity that is incompletely lined by mesoderm. Provides a space for internal organs and can serve as hydrostatic skeleton. Roundworms (phylum Nematoda) Nonsegmented, generally colorless worms. Several parasitic roundworms infect humans. Mader: Biology 8th Ed.

Roundworm Anatomy Mader: Biology 8th Ed.

Trachinella - Trichinosis Dirofilaria - Heartworms Parasitic Roundworms Ascaris Trachinella - Trichinosis Dirofilaria - Heartworms Wuchereria - Elephantiasis Mader: Biology 8th Ed.

Rotifers (phylum Rotifera) Named for crown of cilia resembling a rotating wheel. Serves as both as an organ of locomotion and aids direction of food to mouth. Mader: Biology 8th Ed.

Rotifer Mader: Biology 8th Ed.

Cnidarians and Comb Jellies Hydra Obelia Bilateral Symmetry Flatworms Review Evolution of Animals Sponges Cnidarians and Comb Jellies Hydra Obelia Bilateral Symmetry Flatworms Roundworms Mader: Biology 8th Ed.

Mader: Biology 8th Ed.