Phylum CnidariaPhylum CnidariaCnidos = “Stinging Needle”Cnidos = “Stinging Needle”

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BC jellyfish and sea pen

CoralCoral

• Water temperature must be at least Water temperature must be at least

25 degrees Celsius to survive!!! 25 degrees Celsius to survive!!!

• The Great Barrier Reef in Australia can The Great Barrier Reef in Australia can be seen from outer space!be seen from outer space!

• The remains of billions of individual The remains of billions of individual creatures!creatures!

• Some coral reefs are 300 metres thickSome coral reefs are 300 metres thick

• Some coral reefs are 25000 years old!Some coral reefs are 25000 years old!

CoralCoral

• Water temperature must be at least Water temperature must be at least

25 degrees Celsius to survive!!! 25 degrees Celsius to survive!!!

• The Great Barrier Reef in Australia can The Great Barrier Reef in Australia can be seen from outer space!be seen from outer space!

• The remains of billions of individual The remains of billions of individual creatures!creatures!

• Some coral reefs are 300 metres thickSome coral reefs are 300 metres thick

• Some coral reefs are 25000 years old!Some coral reefs are 25000 years old!

OUCH!OUCH!

Stings from a Stings from a Portuguese Man-of-War Portuguese Man-of-War

4 Classes of Phylum Cnidaria4 Classes of Phylum Cnidaria

HYDROZOA – Obelia, Hydra (above), Portuguese Man O War

SCHYPHOZOA - Jellyfish

ANTHOZOA – anemones (above), corals, sea fans

CUBOZOA – box jellies (sea wasps)

Characteristics - Phylum Cnidaria

• Acoelomates & therefore do not possess any true body systems or organs.

• 2 germ layers include ectoderm (protection), endoderm (inner lining)

• and mesoglea (not a germ layer-it’s the jelly!!!)

• Radial symmetry

Characteristics - Phylum Cnidaria

• Tentacles• Capturing food with stinging cells

(cell:cnidocyte with nematocysts)• Transportation

• Possess a Gastrovascular Cavity (GVC)• Primitive Nervous System (nerve net)• Hermaphroditic : can reproduce sexually

(do not self fertilize) or asexually by regeneration or budding

• Have a motile (medusa) and a sessile (polyp) stage in their lives

NERVE NETNERVE NET

• The first animals to The first animals to have nerve cells.have nerve cells.

• The nerves form a The nerves form a “nerve net”“nerve net”

• There is no brainThere is no brain

• There is no There is no cephalization (a cephalization (a bunching of nerve bunching of nerve cells to form a brain)cells to form a brain)

2 Body Types2 Body Types

PolypPolyp

MedusaMedusa

Gastrovascular Cavity (GVC)Gastrovascular Cavity (GVC)• digestion, circulation, respiration and excretion.digestion, circulation, respiration and excretion.

• Cons: Cons: – only one opening….. The mouth is the anus…..only one opening….. The mouth is the anus…..– Body systems - not separated or specializedBody systems - not separated or specialized

Tentacle

Tentacle Gastrovascular Cavity

Mouth and Anus

Calcified Shell (Coral)Note: This diagram shows the GVC in the polyp body type.

GVC

•Digestion: glands release enzymes into body cavity

•Circulation: via currents generated by body movements & flagella on endodermal cells

•Respiration & Excretion: via diffusion because ectoderm & endoderm are in direct contact with the water

Cnidocyte with the Nematocyst

The stinging cells: NematocystsThe stinging cells: Nematocysts

• Function: to ward off Function: to ward off predators and attack predators and attack preyprey

• Location: Location: end of end of tentaclestentacles

• Special cells called Special cells called cnidocytescnidocytes

• Contain organelle Contain organelle called called nematocystnematocyst

• Produce a Produce a toxintoxin• Action: Releases a Action: Releases a

barbed needle that barbed needle that penetrates the flesh penetrates the flesh and injects toxins and injects toxins when stimulated when stimulated

A discharged nematocyst

Life cycle of a typical JellyfishLife cycle of a typical Jellyfish#1-10 exhibit the formation of the polyp life form.

#11 shows the polyp undergoing asexual reproduction in the form of budding. The top of the polyp breaks off and goes on to form the medusa stage of the jellyfish’s life. (if this was an anemone the polyp would settle on the ocean floor and become a new polyp…. See picture of brooding anemone on next slide)

#12-14 shows the formation of the adult medusa

The medusa will then go on to produce and release egg and sperm into the water. The eggs will be cross fertilized by the sperm of another medusa and eventually develop into a new polyp

This alternating between two life forms is termed ALTERNATION OF GENERATIONS

Brooding Anemones - very common – Other polyps form off existing polyps, break off and then settle on the ocean floor –Asexual reproduction!

Ecological Importance of CnidariansEcological Importance of Cnidarians

• Filter and clean the waterFilter and clean the water• Coral die as water

temperature increases or decreases. – Death of coral often

precedes death of entire ecosystems

Symbiotic relationships of Symbiotic relationships of cnidarianscnidarians

• Coral – a colony of Coral – a colony of polyps in symbiosis polyps in symbiosis with algaewith algae

• Clownfish and Clownfish and anemoneanemone

.Benefit to clownfish: stinging cells do not harm the clownfish, but make the fish toxic to other fish…provide protection and shelterBenefit to anemone: clownfish clean the anemone

Killer CnidariansKiller CnidariansThe Portuguese Man O’ War The Portuguese Man O’ War • a a colony of specialized colony of specialized

polyps and medusas polyps and medusas (not a (not a single jellyfish)single jellyfish)

• sting - sting - causes excruciating causes excruciating pain and sometimes deathpain and sometimes death

• Named for its air bladder Named for its air bladder which looks like the sails of which looks like the sails of a a Portuguese fighting shipPortuguese fighting ship

Super cool fact: Loggerhead Super cool fact: Loggerhead turtles are actually turtles are actually immune immune to their toxins and feed on to their toxins and feed on the Portuguese Man O’ Warthe Portuguese Man O’ War

Portuguese Man O’ War Physalia physalis

A common sign to observe near

Australian Beaches

Box JellyfishBox Jellyfish• Possess the Possess the most deadly most deadly

venom (toxins) venom (toxins) in the in the animal kingdom which animal kingdom which cause anaphylaxis shock cause anaphylaxis shock and deathand death

• In In Nov. – April Nov. – April they are they are abundant in Australian abundant in Australian waters but it is not known waters but it is not known where they go for the where they go for the winterwinter

• Through Through ultrasonic tagging ultrasonic tagging it has been found that they it has been found that they sleep on the ocean floor sleep on the ocean floor between between 3pm and dawn 3pm and dawn to to conserve energy and avoid conserve energy and avoid predatorspredators

• Possess Possess 22 very simple 22 very simple light sensing eyes as well light sensing eyes as well as a more developed eye as a more developed eye 0.1 mm 0.1 mm acrossacross

Box Jellyfish Chironex flecker

This jellyfish has had an ultrasonic tag attached (very carefully!) to it in order to help learn more about the migration patterns of these

cnidarians

JellyJelly FISH OUT OF WATERFISH OUT OF WATER

• http://ca.youtube.com/watch?v=Fm3EmkWMeHY (part 1 http://ca.youtube.com/watch?v=Fm3EmkWMeHY (part 1 cnidaria)cnidaria)

• http://ca.youtube.com/watch?v=QvUZJh9MHt8 (part 2 cnidaria)http://ca.youtube.com/watch?v=QvUZJh9MHt8 (part 2 cnidaria)• http://ca.youtube.com/watch?v=6zJiBc_N1Zk (nematocyst http://ca.youtube.com/watch?v=6zJiBc_N1Zk (nematocyst

firing)firing)• http://ca.youtube.com/watch?v=Dm98n3908QM (swimming http://ca.youtube.com/watch?v=Dm98n3908QM (swimming

anemone)anemone)• http://ca.youtube.com/watch?v=_jNwWQtLeY4 (fighting http://ca.youtube.com/watch?v=_jNwWQtLeY4 (fighting

anemone)anemone)• http://ca.youtube.com/watch?v=JoMCTvRkvxo (national http://ca.youtube.com/watch?v=JoMCTvRkvxo (national

geographic jellyfish)geographic jellyfish)• http://ca.youtube.com/watch?v=JoMCTvRkvxo(anemone/http://ca.youtube.com/watch?v=JoMCTvRkvxo(anemone/

clownfish partnership)clownfish partnership)

• http://www.youtube.com/watch?http://www.youtube.com/watch?v=grTN7BIbzfY comb jellyfishv=grTN7BIbzfY comb jellyfish