chapter 9 n.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
Chapter 9 PowerPoint Presentation
Download Presentation
Chapter 9

Loading in 2 Seconds...

play fullscreen
1 / 44

Chapter 9 - PowerPoint PPT Presentation


  • 202 Views
  • Uploaded on

Chapter 9. Multicellular and Tissue Levels of Organization. Evolutionary Perspective. Porifera No tissues Division of labor among independent cells Independent origin from common animal ancestor Choanoflagellate protists (?) Cnidaria and Ctenophora Tissue level organization

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Chapter 9' - alton


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
chapter 9

Chapter 9

Multicellular and Tissue Levels of Organization

evolutionary perspective
Evolutionary Perspective
  • Porifera
    • No tissues
    • Division of labor among independent cells
    • Independent origin from common animal ancestor
    • Choanoflagellate protists (?)
  • Cnidaria and Ctenophora
    • Tissue level organization
    • Independent origins from common animal ancestor
    • Choanoflagellate protists (?)
  • Origins of Multicellularity
    • At least 800 million years—Precambrian
    • Colonial hypothesis
    • Syncytial hypothesis
slide4

Figure 9.2 Two hypotheses regarding the origin of multicellularity. (a) Colonial hypothesis. (b) Syncytial hypothesis.

phylum porifera
Phylum Porifera
  • Asymmetrical or superficially radially symmetrical
  • Three cell types: pinacocytes, mesenchyme cells, and choanocytes
  • Central cavity, or a series of branching chambers, through which water circulates during filter feeding
  • No tissues or organs
cell types body wall and skeletons
Cell Types, Body Wall, and Skeletons
  • Pinacocytes
    • Outer surface
    • Some contractile, others may be specialized into porocytes
  • Mesohyl
    • Jellylike middle layer
  • Mesenchyme cells
    • Amoeboid cells
    • Reproduction, secreting skeletal elements, transporting and storing food, form contractile rings
  • Choanocytes
    • Flagellated
    • Collarlike ring of microvilli
    • Water currents for filter feeding
  • Skeleton
    • Spicules
    • Spongin
figure 9 6 water currents and body forms
Figure 9.6 Water Currents and Body Forms.
  • Complex sponges have increased surface area for filtering large volumes of water.
maintenance functions
Maintenance functions
  • Filter feeding
    • Bacteria, algae, protists, suspended organic matter
    • Trapped in choanocyte collar and incorporated into food vacuole
    • Digestion by lysosomal enzymes and pH changes
  • Nitrogeneous waste removal and gas exchange
    • Diffusion
  • Coordination
    • Responses of individual cells (some coordination)
reproduction
Reproduction
  • Monoecious
  • Choanocytes (and sometimes ameboid cells) lose collars and flagella and undergo meiosis.
  • External fertilization and planktonic larvae in most
  • Asexual reproduction
    • Gemmules
    • Freshwater and some marine
slide13

Figure 9.7 Development of sponge larval stages.

Parenchymula larva.

(b) Amphiblastula larva.

(c) Gemmule.

(d)

phylum cnidaria
Phylum Cnidaria
  • Radial symmetry or modified as biradial symmetry
  • Diploblastic, tissue-level organization
  • Gelatinous mesoglea between the epidermal and gastrodermal tissue layers
  • Gastrovascular cavity
  • Nerve cells organized into nerve net
  • Specialized cells, called cnidocytes, used in defense, feeding, and attachment
the body wall
The Body Wall
  • Epidermis
    • Outer cellular layer
    • Ectodermal origin
  • Gastrodermis
    • Inner cellular layer
    • Endodermal origin
  • Mesoglea
    • Jellylike
    • Cells present but origins are epidermal or endodermal
nematocysts
Nematocysts
  • Cnidocytes
    • Epidermal or gastrodermal cells that produce cnida
    • 30 types
      • Nematocysts used in food gathering and defense
slide19

Figure 9.10 The generalized cnidarian life cycle involves alternation between a sexual medusa stage and an asexual polyp stage.

maintenance functions1
Maintenance Functions
  • Gastrovascular cavity
    • Digestion
    • Gas exchange
    • Excretion
    • Reproduction
    • Hydrostatic skeleton
      • Support and movement
      • Epitheliomuscular cells act against water-filled cavity.
  • Nerve net coordinates body movements.
reproduction1
Reproduction
  • Medusa
    • Dioecious
    • External fertilization most common
    • Planula larva
  • Polyp
    • Budding produces miniature medusae.
class hydrozoa
Class Hydrozoa
  • Mostly marine
  • Some freshwater
  • Unique features
    • Nematocysts only epidermal
    • Gametes epidermal and released to outside of body
    • Mesoglea largely acellular
    • Medusae with velum
class staurozoa
Class Staurozoa

Figure 9.13 Members of the class Staurozoa are marine and lack a medusa stage. Lucernaria janetae is shown here.

class scyphozoa
Class Scyphozoa
  • Marine
  • Medusa dominant in life history
    • Lacks velum
  • Cnidocytes epidermal and gastrodermal
  • Gametes gastrodermal
    • Dioecious
slide27

Figure 9.14 Representative scyphozoans (a) Mastigias qinquecirrha and (b) Aurelia labiata.

(b)

(a)

class cubozoa
Class Cubozoa
  • Cuboidal medusa
  • Tentacles hang from corners
  • Tropical
  • Dangerous nematocysts

Figure 9.17 The sea wasp, Chironex fleckeri.

class anthozoa
Class Anthozoa
  • Colonial or solitary
  • Lack medusa
  • Cnidocytes lack cnidocils
  • Anemones and corals
  • Mouth leads to pharynx
  • Mesenteries divide gastrovascular cavity and are armed with nematocysts.
  • Mesoglea with ameboid mesenchyme cells
slide32

Figure 9.18 (a) The giant sea anemone (Anthopleura xanthogrammica) and (b) a sea anemone (Callictis parasitical)

living in a mutualistic relationship with a hermit crab.

reproduction2
Reproduction
  • Asexual
    • Pedal laceration
    • Longitudinal or transverse fission
  • Sexual
    • Monoecious or dioecious
    • External fertilization produces planula.
    • Monoecious species
      • Protandry
        • Male gametes mature first.
corals
Corals
  • Stony
    • Reef forming
    • Lack siphonoglyphs
    • Cuplike calcium carbonate exoskeleton
    • Asexual budding expands colony.
    • Symbiotic relationship with zooxanthellae
corals1
Corals
  • Octacorallian
    • Warm waters
    • Eight pinnate tentacles
    • Eight mesenteries
    • Internal protein or calcium carbonate skeleton
phylum ctenophora
Phylum Ctenophora
  • Diploblastic or possibly triploblasitic
  • Biradial symmetry
  • Gelatinous, cellular mesoglea
  • True muscle cells
  • Gastrovascular cavity
  • Nerve net
  • Colloblasts
  • Eight comb rows
phylum ctenophora1
Phylum Ctenophora
  • Cellular mesoglea and true muscle cells suggest that members may be triploblastic.
  • Locomotion by bands of cilia are called comb rows.
  • Tentacles contain adhesive cells called colloblasts that capture prey.
  • Monoecious with gastrodermal gonads
    • External fertilization leads to flattened larval stage.
slide42

Figure 9.22 (a) The bioluminescent ctenophoran Mnemiopsis sp. (b) The structure of Pleurobranchia. (c) Colloblast structure.

(a)

further phylogenetic considerations
Further Phylogenetic Considerations
  • Porifera
    • Oldest fossil deposits
    • Choanoflagellate ancestors
    • Increases surface-to-volume ratio in syconoid and leuconoid body forms evolved in response to selection for increased size.
  • Cnidaria
    • Radially symmetrical ancestor
      • Minority view suggest bilateral ancestor.
    • Molecular data and morphology suggests relationships shown in figure 9.23.
  • Ctenophora
    • Relationships to other groups uncertain but probably distant