Animals I

  1. "Parazoa" : Phylum Porifera
    • sponges; only extant parazoa group
    • Classes:
    • Calcarea (calcium carbonate spicules)
    • Silicea (glass spicules)
    • Demospongia (glass spicules and/or spongin fibers)
  2. Phylum Cnidaria
    • Classes:
    • Hydrozoa (Hydra)
    • Scyphozoa (true jellies; Aurelia)
    • Anthozoa (anemenies/corals; Metridium)
  3. Phylum Platyhelminthes
    • flatworms
    • Classes:
    • Turbellaria (planaria)
    • Trematoda (flukes)
    • Cestoda (tapeworms)
  4. Phylum Nematoda
  5. Kingdom Animalia derived characteristics
    • multicellular
    • descended from a hypothetical flagellated protist ancestor
    • artificial taxons include parazoa and eumetazoa
  6. eumetazoa
    • all other animal phyla besides porifera
    • differentiated cells
    • true tissues derived from germ layers
  7. diploblastic
    • 2 germ layers - endoderm and ectoderm
    • cnidarians
  8. ectoderm
    • outermost primary germ layer in animal embryos
    • gives rise to outer covering, skin, and its accessory organs; nervous system
  9. endoderm
    • innermost primary germ layer
    • gives rise to digestive tract lining and its accessory organs; lungs
  10. mesoderm
    • germ layer between ectoderm and endoderm
    • mesodermally-derived cells include the coelom lining and organs
  11. triploblastic
    consists of 3 germ layers - ectoderm, mesoderm, endoderm
  12. radial symmetry
    • cnidarians, echinoderms
    • divided by many planes through the central axis of its body
    • top (oral side with mouth) and bottom (aboral side)
    • no distinct head
  13. asymmetrical
    • no symmetry
    • sponges
  14. bilateral symmetry
    • divided into mirror halves through one longitudinal plane (medial)
    • right and left sides (lateral)
    • distinct head (anterior) and tail (posterior)
  15. cephalization
    an evolutionary trend towards concentrating sensory and nervous system at the anterior end of the organism
  16. no possession of a coelom
    • lack mesoderm
    • includes porifera and diploblastic animals (cnidarians)
  17. coelom
    • body cavity
    • usually deveoped from mesoderm layers
  18. acoelomates
    • do not possess a coelom
    • possess mesoderm
    • platyhelminthes
  19. pseudocoelomates
    • possess an internal fluid-filled cavity, but the cavity is incompletely lines with mesoderm-derived tissue
    • nematoda
  20. coelomates
    • include most animal phyla
    • coelom forms during embryonic development
    • fluid-filled cavity completely lined with mesodermally-derived cells
    • organs are suspended by double layers (mesenteries)
  21. a coelom is important because it provides:
    • room for organs to grow and develop
    • an increased surface area for gas exchange and nutrient transport into/out of organs
    • a hydrostatic skeleton for support and movement
    • a place to store materials
    • a route to pass wastes and gametes to the outside
  22. internal skeleton (sponges)
    • composed of spicules
    • Calcarea (calcareous spicules)
    • Silicea (glass spicules)
    • Demospongiae (protinaceous spicules, spongin)
  23. body specialization (sponges)
    • no cephalization
    • no segmentation
    • every cell exchanges gases and eliminates wastes through diffusion
  24. adaptations for a sessile lifestyle (sponges)
    no distinct nervous, muscular, or endocrine systems
  25. cellular level of organization (sponges)
    • no tissues, organs, organ systems
    • no obvious body symmetry
    • somatic regeneration - isolated cells can aggregate and form a new sponge
    • totipotent - each cell can potentially give rise to any other cell type
  26. digestive system (sponges)
    • none; no germ layers, digestive tract, or coelom
    • pores and canals lead to the central spongocoel, through which water moves
    • digestion occurs in the choanocytes and amebocytes
    • intracellular digestion
  27. choanocytes (sponges)
    • flagellated cells that are involved in many activities
    • important in intracellular digestion
  28. amebocytes (sponges)
    • amoeboid cells involved in intracellular digestion (receive food vacuoles from choanoctyes) and food transport
    • involved in spicule production, reproduction, contraction
  29. ostia and water flow (sponges)
    • small; lead to small incurrent canals
    • -- in the spongocoel
    • -- water exits through a large, single osculum (outcurrent pore)
    • water currents formed by teh beating of choanocyte flagella lining the radial canals
  30. pinacocytes (sponges)
    think, plate-like cells lining the outside of the sponge, the spongocoel, and canals
  31. mesohyl (sponges)
    • thin, gel-like matrix
    • amebocytes scattered here throughout
  32. reproduction (sponges)
    • cell clusters are sponge larvae, called amphiblastulas (formed by the zygote undergoing mitosis)
    • eggs retained in the mesohyl, sperm captured by choanocytes; fertilization considered internal
    • amphiblastulas break through the spongocoel and exit out the osculum
    • reproduce asexually by fragmenting and budding
  33. body plan (cnidarians)
    • diploblastic
    • acoelomate
    • mesoglea - an acellular gelatinous layer between the two dermal layers
    • radial symmetry
    • unsegmented
  34. body forms (cnidarians)
    • sessile polyp - hydrozoans and anthozoans
    • free-swimming medusa - scyphozoa
  35. integumentary systems (cnidarians)
    • no specialized integument
    • some colonial species have a protective outer covering composed of proteins, polysaccharides, and chitin (collectively called the perisarc) that surrounded all of the polyps
    • epidermis contains cnidocytes
  36. cnidocytes
    • stinging cells
    • possess a spiked, harpoon-like organelle (nematocyst) that can be discharged
    • pierce, entangle, paralyze prey; self-defense
  37. digestive systems (cnidarians)
    • occurs extracellularly in the gastrovascular cavity
    • fluids move through due to body wall contractions and ciliated actions in the gastrodermis
    • mostly carnivorous diet
    • some have symbiotic algae living inside of them (eg, coral)
  38. respiratory/circulatory systems (cnidarians)
    • no specialized circulatory, respiratory systems
    • simple diffusion of gases across body wall
    • ciliary action can move contents in the gastrovascular cavity
  39. osmoregulatory/excretory systems (cnidarians)
    no specialized systems
  40. nervous systems (cnidarians)
    • simple nerve net
    • no brain/cephalization
    • bidirectional synapses - nerve potentials can go both ways across a synapse (unique)
    • neurosensory cells that can respond to light, touch, balance
  41. reproductive systems (cnidarians)
    • reproduce asexually by budding
    • sexually; either medusa or polyps produce both the eggs and sperm
    • external fertilization
    • generally dioecious
  42. skeletal systems (cnidarians)
    • no major support structures
    • coral species form an exoskeleton made of calcium carbonate
  43. muscular systems (cnidarians)
    cells found in both the epidermis (epitheliomuscular cells) and in the gastrodermis (nutritive-muscular cells) are capable of contraction
  44. Aurelia life cycle (cnidarian)
    • ciliated larval stage (the planula) settles on the bottom, forming a polyp (the scyphistoma)
    • the scyphistoma eventually becomes the strobila
    • the strobila forms many medusae asexually, by budding
    • the ephyra is a young medusa that matures into a dioecious adult
  45. Obelia life cycle (colonial hydrozoan cnidarian)
    • is a thecate - the polyp is mostly coverd in a sheath
    • entire colony encased in a transparent protective tube (perisarc)
    • colonies grow by asexually budding polyps
    • form multiple medusae by budding; medusae grow into dioecious, sexually mature adults, which externally fertilize a zygote; grows into planula larva, which settles and develops into a polyp; young polyp grows by reproducing asexually through budding
  46. gastrozooids (polyp type in sessile hydrozoan colonies)
    feeding polyp with tentacles
  47. gonozooids (polyp type in sessile hydrozoan colonies)
    • reproductive polyps
    • -- see "Obelia life cycle"
  48. hydrorhiza (hydrozoan colony)
    • a stolon attached to the substrate
    • gives rise to stalks, called hydrocauli
    • the living part of the hydrocauli is called the coenosarc, which surrounds a common gastrovascular cavity
    • individual polyps (zooids) are attached to the hydrocaulus
  49. anthozoans (cnidarians)
    • all are marine
    • only have polyp stage
    • includes corals
    • secrete a protective outer skeleton of calcium carbonate
    • make up the larges class of cnidarians
  50. body plan (platyhelminthes)
    • dorsoventrally flattened body
    • triploblastic
    • acoelomate
    • unsegmented (tapeworms produce structures called protoglottids, which make them appear segmented)
    • bilateral symmetry
    • organ system level of organization - distinct tissues and organs including epithelial, muscular, and nervous tissues
  51. osmoregulatory/excretory systems (platyhelminthes)
    • protonephridium - closed tubular systems that open to the outside along the length of the body at various points called nephridiopores
    • nitrogenous wastes (ammonia) diffuse out of each cell into the environment
  52. respiratory/circulatory systems (platyhelminthes)
    • no specialized systems
    • parasitic flatworms typically use anaerobic respiration
  53. digestive systems (platyhelminthes)
    • incomplete digestive tract consisting of a gastrovascular cavity
    • initially extracellular digestion, followed by intracellular digestion inside cells lining the gastrovascular cavity
    • in some parasitic species, the digestive tract is much reduced or absent; obtains its food in predigested form (by the host)
  54. nervous systems (platyhelminthes)
    • cephalization
    • cerebral ganglia in the anterior end and several pairs of lateral nerve cords running along the length of the body
    • nerve cells are unidirectional
    • parasitic flatworms often exhibit reduced cephalization and lack sensory organs
    • distinct sensory neurons and motor neurons
    • receptor organs that respond to light, tough, chemicals, gravity, and currents
  55. diet and living situation (platyhelminthes)
    • free-living carnivores
    • parasites within the digestive, respiratory, circulatory systems
  56. reproductive systems (platyhelminthes)
    • typically monoecious
    • cross-fertilize (exchange sperm with another organism)
    • parasitic tapeworms may self-fertilize
    • internal fertilization
  57. integumentary systems (platyhelminthes)
    • distinct integument that protects their body from the host's digestive enzymes
    • move by muscular action and by ciliary action - mucus serves as a lubricating slime as the animal moves
    • can regenerate lost body parts; cells are not totipotent
  58. muscular systems (platyhelminthes)
    • ciliary motion
    • circular and longitudinal muscles are present in the body wall
    • thrash about
  59. Clonorchis life cycle (platyhelminthes fluke: Class Trematoda)
    • larval stages (miracidia) that hatch from eggs
    • infect intermediate hosts (aquatic snails); a single miracidium forms a single mother sporocyst within the snail hemocoel; asexually forms daughter parasites; germ cells within the sporocyst may develop into redia, larvae with mouths and gastrovascular cavities; within redia, germ balls develop into cercariae, another distinct larval stage
    • cercaridae burrow through the snail's body wall; with a muscular tail, they infect a second intermediate host (fish) where the larva encyst as metacercariae
    • a human eats the fish (plus encysted metacercariae); inside the human's digestive tract, the adult flukes leave the metacercariae cysts; mature and produce eggs; eggs are passed through the feces and into water again, where miracidia hatch from them
  60. Schistosoma life cycle (platyhelminthes fluke: Class Trematoda)
    • adults live in veins; eggs leave through feces and into water
    • miracidium excysts from an egg; burrows into an intermediate host (snail) and becomes a mother sporocyst, which asexually produces daughter sporocysts which mature in the snail's digestive tract
    • each daughter sporocyst produces many cercariae, which burrow out of the snail and into the exposed skin of a human host; then loses its tail and becomes a young schistosomule, traveling through the circulatory system and maturing into adults
    • no metacercaria stages
    • males have split bodies with females inside (called the gynocophoral canal)
  61. Taenia life cycle (platyhelminthes tapeworm: Class Cestoda)
    • generally lack a digestive system, developed the ability to absorb nutrients across their body wall (from the contents of their host); sensory systems are much reduced or absent
    • the scolex (head) often contains suckers/hooks that allow the tapeworm to attach to the intestinal wall
    • remainder of the body consists of segments called protoglottids, each of which contains both testes and ovaries (produced asexually by budding); eggs (within protoglottids or relased from) exis with the host's feces; picked up by an intermediate host, where they eggs hatch into larvae and encyst in muscles
    • the human (final/definitive host) eats the intermediate host
  62. body plan (nematodes)
    • roundish, cylindrical
    • unsegmented
    • tapered ends
    • pseudocoelom
    • triploblastic
    • bilaterally symmetrical
    • cephalization
    • exhibit eutely - each individual consists of exactly the same number of cells (unique)
  63. muscular systems (nematodes)
    • only longitudinal muscles in the body wall (no circular or diagonal muscles)
    • no muscles surround the roundworm's digestive tract
    • pressure is exerted on the contents of the gut by hydrostatic pressure
    • muscles send processes to the nerves for innervation, not vice versa (unique)
  64. digestive systems (nemetodes)
    • complete digestive tract
    • unidirectional
    • pharynx present
    • extracellular digestion within the gut, followed by intracellular digestion
  65. integumentary systems (nematodes)
    • cuticle (containing chitin) produced by the epidermis
    • typically have four molts and four larval stages
    • the cuticle maintains turgor pressure, prevents the worm from drying out quickly, provides mechanical protection, and is resistant to digestion by the host's digestive tract (for parasites)
    • cuticle is similar to cuticle of arthropods
  66. diet and living situation (nematodes)
    • free-living carnivores
    • free-living detrivores (feed on dead plant and animal tissue)
    • parasites
    • sound in marine, freshwater systems, moise soils, and in the tissues and fluids of nearly all plants and animals
  67. respiratory/circulatory systems (nematodes)
    • no specialized systems
    • gases diffuse across body wall
    • parasitic forms may use anaerobic respiration
  68. osmoregulatory/excretory systems (nematodes)
    • series of excretory canals
    • no flame bulbs
    • renette cells - special excretory cells that absorb nitrogenous wastes, which can be passed through a pore outside
    • eliminate ammonia via the gut (similar to arthropods)
  69. reproductive systems (nematodes)
    • dioecious
    • internal fertilization
  70. skeletal systems (nematodes)
    use a hydrostatic skeleton (from the pseudocoelom) and the cuticle to provide structure
  71. nervous systems (nematodes)
    • simple
    • cephalization
    • nerve cords run posteriorly
    • several sense organs for touch; a few can detect light
  72. Ascaris life cycle (nematodes)
    • intestinal
    • eggs deposited in the host's feces; development occurs inside the egg, two larval molts occur inside the egg; after ingestion, they hatch or cyst in the host's intestines, then find their way to the lungs; work its way to being swallowed again, back down to the small intestine
Card Set
Animals I
Unit 18