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Tree of Life. The tree of life according to Ernst Haeckel, 1891. How does Porifera fit in?. Porifera. 3 body types . Other animals. choanocytes. cellular level of organization. Blastula stage. heterotrophic. multicellular. eukaryote. unknown common ancestor.

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tree of life
Tree of Life

The tree of life according to

Ernst Haeckel, 1891

how does porifera fit in
How does Porifera fit in?

Porifera

3 body types

Other animals

choanocytes

cellular level

of organization

Blastula stage

heterotrophic

multicellular

eukaryote

unknown

common ancestor

how does cnidaria fit in
How does Cnidaria fit in?

Cnidaria

Porifera

Other animals

3 body types

choanocytes

cellular level

of organization

Blastula stage

heterotrophic

multicellular

unknown

common ancestor

eukaryote

level of organization
Level of Organization

Tissue

  • cells are organized into tissues and work together to accomplish physiological functions
tissue layers
Tissue Layers
  • Diploblastic = 2 germ layers
        • endoderm  gastrodermis
        • ectoderm  epidermis
  • mesoglea
      • gelatinous matrix between the 2 layers

gastrovascular

cavity

epidermis

mesoglea

gastrodermis

general body plan
General Body Plan
  • sac-like body (only 1 opening)
  • Food and waste go in/out the same opening
  •  no anus!
  • water within GVC acts as a hydrostatic skeleton

oral surface

mouth

gastrodermis

Gastrovascular

cavity

mesoglea

epidermis

aboral surface

general body forms
General Body Forms

2 different body forms are usually present in the life cycle:

polyp & medusa

** one animal may pass through both forms during its life **

radial symmetry
Radial Symmetry
  • - body parts are arranged concentrically around an oral-aboral axis

oral

aboral

nematocysts
Nematocysts
  • specialized stinging organelles
  • found within cnidocytes (cells)
  • cnidocytes are located in epidermis

A cnidocyte with a nematocyst within it

nematocysts12
Nematocysts
  • nematocysts are like “mini-harpoons”
  • cnidocil senses movement & acts like a “trigger”
  • can inject poison, coil around prey, or be adhesive
  • functions:
    • - prey capture; defense

nematocyst

cnidocil

cnidocyte

Undischarged

Discharged

colony formation
Colony formation
  • colony formation is common (colonial animals)
  • occurs via asexual reproduction (e.g. fission)
  • individual polyps are connected to one another by the GVC

individual polyp

physiology
Physiology

Feeding

  • nematocysts within cnidocytes
  • tentacles

Digestion

  • extracellular (in GVC)
  • intracellular (by gastrodermal cells)
  • incomplete system (no anus)

Gas exchange & Excretion

  • these systems are absent
physiology15
Physiology

Nervous System

  • nerve net

(no central nervous system= no brain)

  • sense organs
      • statocysts (equilibrium organs)
      • ocelli (photosensitive organs)

Skeletal System

  • water in GVC acts as a hydrostatic skeleton
physiology16
Physiology

Reproduction

Asexual

  • budding
  • longitudinal fission
  • pedal laceration

(e.g. sea anemones)

physiology17
Physiology

Reproduction

Sexual

  • usually dioecious

(separate sexes e.g. humans)

  • monoecious

(both male + female gonads in 1 individual)

  • results in Planula larva
phylum cnidaria18
Phylum Cnidaria

Class Hydrozoa

Class Scyphozoa

Class Anthozoa

class hydrozoa
Class Hydrozoa
  • medusa & polyp body forms

Fire coral

class hydrozoa20
Class Hydrozoa
  • medusa & polyp body forms
  • most are colonial
  •  colonies are formed of individual zooids

a single zooid

class hydrozoa21
Class Hydrozoa
  • many of these colonies show polymorphism
  •  this is where there are several different types of polyps/zooid and each type is specialized for a different function
  • e.g. gastrozooids = feeding polyps
  • e.g. dactylzooids = defense polyps
  •  all the zooids within a colony are genetically identical
  •  these different zooids work together in the colony
class hydrozoa22
Class Hydrozoa

- a sessile colony showing polymorphism

gonozooid

entire

colony

gastrozooid

class hydrozoa23
Class Hydrozoa

- a Portugese Man-o-war is a floating hydrozoan colony showing polymorphism

pneumatophore

entire

colony

gastrozooid

dactylzooid

class hydrozoa life cycle
Class Hydrozoa- life cycle

sexual

reproduction

asexual

reproduction

class hydrozoa25
Class Hydrozoa
  • Hydra is an example of a solitary, freshwater hydrozoan

asexual

reproduction

sexual

reproduction

gonads

bud

class scyphozoa
Class Scyphozoa
  • “true” jellyfish
  • medusa & polyp body forms
  • thick mesoglea
class scyphozoa life cycle
Class Scyphozoa- life cycle

sperm

egg

ephyra

Adult medusa

strobila

scyphistoma

larva

class anthozoa
Class Anthozoa
  • polyp body form ONLY
  • all marine
class anthozoa29
Class Anthozoa
  • some are colonial
  •  colonies are formed of individual zooids
  • some are solitary
class anthozoa30
Class Anthozoa

Sea anemones

class anthozoa31

Sea pansy

Class Anthozoa

Soft Corals

Sea pen

class anthozoa32
Class Anthozoa

Stony Corals

class anthozoa life cycle
Class Anthozoa- life cycle

Sexual reproduction

sperm

egg

larva

class anthozoa life cycle34
Class Anthozoa- life cycle

asexual reproduction

fission

pedal laceration

fission

how does cnidaria fit in35
How does Cnidaria fit in?

Cnidaria

3 classes:Hydrozoa, Scyphozoa, Anthozoa

Porifera

2 body types: polyp, medusa

diploblastic

3 body types

tissue level

of organization

choanocytes

cellular level

of organization

Blastula stage

heterotrophic

multicellular

unknown

common ancestor

eukaryote

symbiosis
Symbiosis

Mutualism –

  • Corals contain endosymbiotic algae called zooxanthellae
  • the zooxanthellae photosynthesize and provide food for the coral while the coral provides a safe home

zooxanthellae

symbiosis37
Symbiosis

Mutualism –

  • Many species of anemone fish (clown fish) live within anemones and are immune to their stinging nematocysts
  • the fish may lure in other fish for the anemone to capture and eat, while the anemone provides protection and a home
coral reefs
Coral Reefs
  • What are they?
    • stony corals lay down a calcium carbonate skeleton
    • these skeletons are laid down on top of one another and over thousands of years, form large calcium carbonate structures
    • these large structures, along with the plants and animals that inhabit them, are known as coral reefs
  • Where do they form?
    • in optimal conditions for their zooxanthellae
      •  shallow, warm, nutrient-poor waters
importance of coral reefs
Importance of Coral Reefs
  • one of the most productive ecosystems although the water is nutrient-poor
  • “hot spots” for biodiversity
threats to coral reefs
Threats to Coral Reefs
  • over-enrichment of nutrients from sewage and agricultural run-off
  • overfishing of herbivorous fish
  • global warming (leads to coral bleaching where corals expel their zooxanthellae)