Download Phylum Cnidaria

Phylum Cnidaria
 Coral Reef David Att.

Taxonomy
Kingdom Animalia
Phylum Cnidaria
Class Hydrozoa
(Hydra, Man-o-war)
Class Cubozoa
(cube jellyfish)
Class Scyphozoa
(true jellyfish)
Class Anthozoa
(anemones, coral)
Phylum Cnidaria
Examples:
 Sea anemones
 Corals
 Sea Pen
 Sea Fan
 Sea Plume
 Hydra
 Jelly fish
 Portuguese Man o’ War
 Box Jelly Fish
General Characteristics
cnidarians
1. More complex than sponges but still very simple animals
2. Most are sessile (corals) but some are sedentary (jellyfish)
3. Found in all oceans and at all depths
4. Live in colonies or free-living
5. All have radial symmetry
6. Most have tentacles with stinging cells
Man of War
Body Plan
1. Polyp- attaches to a rock or coral at its base (anemone)
2. Medusa – has a bell with tentacles hanging down
(jellyfish)
Body Plan
Body Layers
 Ectoderm: the outer layer that contains sensory organs and
nerves
 Mesoglea: the middle, jelly-like substance containing little to
no cells
 Endoderm: the inner layer containing muscle cells and cilia
for movement
Cnidocytes
 Cnidocytes: cells found in the tentacles that sting and
have venom
 Used to capture and subdue prey and to protect against
predators
 How Jellyfish Sting
Cnidocytes
Most are not harmful to humans, however Portuguese man-ofwar and certain jellyfish are quite painful and sometimes
dangerous
Locomotion
 Polyps: move around by sliding, “inch worming” or
summersaulting
 Medusa: move by contracting muscles and expelling water
from their bell
 cnidarian movement
Feeding and Digestion
 The mouth opens into the gastrovascular cavity where
enzymes are released to digest food
 cnidarians feeding
Reproduction
Polyps
 1. Budding: a knob of tissue forms on the side
of the “parent”
 The bud develops into an adult and the
offspring detaches
 Detached: free-living clone of the parent
 Undetached: stay together and live as a
colony
Reproduction
 2. Fission
 The polyp splits in half
forming 2 identical animals
 3. Pedal Laceration
 tissue is torn from the basal
disc and develops into a
new identical offspring
Reproduction
Medusa
 Sexual reproduction only!
 Sperm and egg get released into the water where fertilization
occurs
 coral spawning
 jellyfish life cycle
Ecological Relationship
1. Neurotoxins are useful in medical research
2. Build coral reefs that are habitats for many other species
3. Used to make jewelry
4.
Ecological Relationship
4. Have mutualistic relationships with other species
Mutualism: when 2 species benefit from living with each
other
 Fish living within tentacles of a man o’ war
 Anemone & clown fish
Class Hydrozoa
 Hydra, man-o-war
 Alternate between polyp and
medusa stage
 Most live in colonies
 Found in salt and fresh water
Portuguese man-of-war
Man o' war
Portuguese man-of-war attack
Class Scyphozoa: true jellyfish
 Includes most jellyfish
 Medusa is the dominant stage
 Have a bettr developed nervous system than most cnidarians
 How to live forever: be a jellyfish
 Jellyfish
 jellyfish documentary
Giant Jellyfish
Northern Sea Nettle
Class Cubozoa
 Cube Jellyfish
 Bells are square with tentacles on the 4 corners
 All are active predators
 Their sting can be fatal to humans
Irukandji jellyfish
Sea Wasp
Box Jellyfish
Box Jelly Video
 box jelly

Sting of a Sea Wasp
 The venom has cardiotoxic, neurotoxic and highly
dermatonecrotic components
Class Anthozoa: Flower Animals
 Anemones, corals, sea fans, sea pen, sea pansies
 Have no medusa stage
 Live alone or in colonies
 Have more developed muscle cells
 Build coral reefs
Sea anemone
Coral reef
A Closer Look at Coral
coral
Tube anemone
Sea fans
Sea pens
Sea Pansies
Phylum Ctenophores
Ctenophores
 Examples: “sea walnuts” and “comb jellies”
 General Characteristics:
 Live in warm, tropical waters
 Have bioluminescent, transparent bodies
 Fewer than 100 species exist
Form and Function
 Form and function: they have a few tentacles with sticky
cells instead of stinging cells to catch prey
 Have cilia for movement
 Colloblasts: sticky cells used to catch prey
 Reproduction: Monoecious, both sexual and asexual
reproduction
Sea Walnut
Comb Jelly
Comb Jelly
 Coral Reef
 breat barrier reef
 BBC great barrier reef