Invertebrates Chapter 28 PDF

INVERTEBRATES Chapter 28  Invertebrates 97% of all species within Kingdom Animalia are invertebrates Invertebrates lack a spine and cranium There are unicellular and multicellular organisms Inhabit land, freshwater, and oceans There are 8 phyla of invertebrates: Porife...

INVERTEBRATES Chapter 28  Invertebrates 97% of all species within Kingdom Animalia are invertebrates Invertebrates lack a spine and cranium There are unicellular and multicellular organisms Inhabit land, freshwater, and oceans There are 8 phyla of invertebrates: Porifera, Cnidaria, Platyhelminthes, Mollusca, Annelida, Nematoda, Arthropoda, Echinodermata Within each phylum, we will consider adaptations in gas exchange, food ingestion/digestion, waste removal, nervous/sensory organs.  Phylum Porifera – the sponges Tissues: They do not have “true” tissues They are not truly diploblastic or triploblastic They do not create a true gastrula Do not create true endoderm and ectoderm They do have specialized cells that perform “tissue-like” functions So,they do have tissues but not tissues that are homologous to the other animals Their larvae are flagellated and swim, but they settle on a substrate and then grow into an adult Adult is not motile Theyobtain nutrients and oxygen from the water – filter feeders Their body is organized in a way to allow efficient movement of water through the sponge  Poriferan morphology Body Plan: Asymmetrical Theyare neither protostome nor deuterostome because they do not have gastrulation Sponges have the general shape of a cylinder The large, internal cavity is called the spongocoel Water flows into the spongocoel through pores called ostia The water is expelled through a large opening at the top of the sponge called the osculum Sponge video  Poriferan physiology Sponges lack digestive, nervous, respiratory, and circulatory systems Foodis digested intracellularly Absorbed by cells inside the spongocoel Gas exchange, circulation and waste excretion are processed through diffusion All cells in the spongocoel can absorb O2, release CO2, and excrete nitrogenous waste Intercellullar communication for contraction and choanocytes Reproduction: Both sexually and asexually  Phylum Porifera (the sponges) Body symmetry: Asymetrical No gastrulation So not diploblastic or triploblastic No true ectoderm or endoderm tissue Have tissues but not homologous to the other animals Filter feeders Adults nonmotile Water flows into spongocoel through ostia, expelled through osculum No digestive system – food digested intracellularly No respiratory system – gas exchanged through cells in spongocoel No nervous system, only intercellular communication Reproduction: Sexual and asexual  Phylum Cnidaria – jellyfish, anemones Body Plan: Radial or biradial symmetry Tissues: Diploblastic They are neither protostome nor deuterostome Incomplete Digestive System Food enters & waste leaves the same opening Almost all are marine organisms Defining character is a cnidocyte, or stinging cell Located on tentacles and around the mouth Catch prey and protect against predators Cnidocytes have stinging organelles called nematocysts Anemone fight Cnidarian body plan  Cnidarian morphology Two body types: Polyp and Medusa Polyp species are sessile Medusa species are motile Epidermis is derived from ectoderm tissue Gastrodermis is derived from endoderm tissue Non-living mesoglea tissue between them They have specialized, differentiated tissue cells but no true organ systems Nerve cells but no nervous system Contractile epithelial cells for movement Enzyme excreting cells and nutrient absorbing cells but no digestive system  Cnidarian physiology Notrue nervous system Network of nerve cells throughout body Gastrovascularcavity has one opening Both mouth and anus Digestive system: Incomplete Digestion begins extracellularly Enzymes excreted into the gastrovascular cavity begin digestion Cells absorb nutrients Nutrients are distributed through the mesoglea to the epidermal cells Cells in the gastrovascular cavity and in the epidermis absorb O2 and release CO2 Nitrogenous waste diffuses out of cells into the gastrovascular cavity or the water surrounding the epidermis  4 Cnidarian Classes Class Anthozoa Only sessile polyp species Coral, sea fans, sea anemones Class Scyphozoa Medusa species Jelly fish Class Cubozoa Medusa species Box jellies Class Hydrozoa Sessileand medusa species Hydra, Portuguese man o’ war  Phylum Cnidaria (jellyfish, anemones, corals, etc) Body symmetry: Radial or Biradial Diploblastic Not protostome or deuterstome Incomplete digestive system Polyps (nonmotile) and Medusa (motile) body types Epidermis from ectoderm tissue Gastrodermis from endoderm tissue No organ systems No digestive system – food digested in gastrovascular cavity No respiratory system – gas exchanged through cells in gastrovascular cavity No nervous system, have nerve cells for movement Have Cnidocytes Reproduction: Mostly sexual but some are asexual  Phylum Platyhelminthes - flatworms Body Plan: Bilateral Tissues: Triploblastic, acoelomate Protostome Incomplete Digestive System Have simple cephalization Nerve tissues and sensory organs in a head May be free-living or parasitic Free-living species are predators or scavengers Digestive system: Incomplete Mouth is also anus Ingested food goes into rudimentary digestive system Food is digested extracellularly then absorbed into cells of gut Waste products are returned to the gut then released through the mouth/anus  Phylum Platyhelminthes - flatworms Excretory system is a network of tubules running along the periphery of the animal. Have flame cells with cilia that propel waste fluid out of the body through pores Nervous system is only two nerve cords running the length of the body Two cerebral ganglia for sensing light and chemicals Nocirculatory or respiratory systems Gas exchange through epidermis Nutrients are distributed through gap junctions Reproduction: Most are monoecious Internal fertilization, produce eggs Platyhelminthes video Phylum Platyhelminthes - flatworms  Phylum Platyhelminthes (the flatworms) Body symmetry: Bilateral with very simple cephalization Triploblastic - acoelomate Protostome Incomplete digestive system Rudimentary digestive system – food digested in intestine No respiratory system – gas exchanged through epidermis Simple nervous system Two cerebral ganglia and two nerve cords Reproduction: Most are monoecious and reproduce sexually, some reproduce asexually