Phylum Cnidaria Cnidos = “Stinging Needle”

BC jellyfish and sea pen

Coral 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 be seen from outer space! The Great Barrier Reef in Australia can be seen from outer space! The remains of billions of individual creatures! The remains of billions of individual creatures! Some coral reefs are 300 metres thick Some coral reefs are 300 metres thick Some coral reefs are years old! Some coral reefs are years old!

Coral 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 be seen from outer space! The Great Barrier Reef in Australia can be seen from outer space! The remains of billions of individual creatures! The remains of billions of individual creatures! Some coral reefs are 300 metres thick Some coral reefs are 300 metres thick Some coral reefs are years old! Some coral reefs are years old!

OUCH!

Stings from a Portuguese Man-of-War

4 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 NET The first animals to have nerve cells. The first animals to have nerve cells. The nerves form a “nerve net” The nerves form a “nerve net” There is no brain There is no brain There is no cephalization (a bunching of nerve cells to form a brain) There is no cephalization (a bunching of nerve cells to form a brain)

2 Body Types PolypMedusa

Gastrovascular Cavity (GVC) digestion, circulation, respiration and excretion. digestion, circulation, respiration and excretion. Cons: Cons: – only one opening….. The mouth is the anus….. – Body systems - not separated or specialized 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: Nematocysts Function: to ward off predators and attack prey Function: to ward off predators and attack prey Location: end of tentacles Location: end of tentacles Special cells called cnidocytes Special cells called cnidocytes Contain organelle called nematocyst Contain organelle called nematocyst Produce a toxin Produce a toxin Action: Releases a barbed needle that penetrates the flesh and injects toxins when stimulated Action: Releases a barbed needle that penetrates the flesh and injects toxins when stimulated A discharged nematocyst

Life 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 Cnidarians Filter and clean the water Filter and clean the water Coral die as water temperature increases or decreases. –Death of coral often precedes death of entire ecosystems

Symbiotic relationships of cnidarians Coral – a colony of polyps in symbiosis with algae Coral – a colony of polyps in symbiosis with algae Clownfish and anemone Clownfish and anemone. Benefit to clownfish: stinging cells do not harm the clownfish, but make the fish toxic to other fish…provide protection and shelter Benefit to anemone: clownfish clean the anemone

Killer Cnidarians The Portuguese Man O’ War a colony of specialized polyps and medusas (not a single jellyfish) a colony of specialized polyps and medusas (not a single jellyfish) sting - causes excruciating pain and sometimes death sting - causes excruciating pain and sometimes death Named for its air bladder which looks like the sails of a Portuguese fighting ship Named for its air bladder which looks like the sails of a Portuguese fighting ship Super cool fact: Loggerhead turtles are actually immune to their toxins and feed on the Portuguese Man O’ War Portuguese Man O’ War Physalia physalis

A common sign to observe near Australian Beaches

Box Jellyfish Possess the most deadly venom (toxins) in the animal kingdom which cause anaphylaxis shock and death Possess the most deadly venom (toxins) in the animal kingdom which cause anaphylaxis shock and death In Nov. – April they are abundant in Australian waters but it is not known where they go for the winter In Nov. – April they are abundant in Australian waters but it is not known where they go for the winter Through ultrasonic tagging it has been found that they sleep on the ocean floor between 3pm and dawn to conserve energy and avoid predators Through ultrasonic tagging it has been found that they sleep on the ocean floor between 3pm and dawn to conserve energy and avoid predators Possess 22 very simple light sensing eyes as well as a more developed eye 0.1 mm across Possess 22 very simple light sensing eyes as well as a more developed eye 0.1 mm across 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

Jelly FISH OUT OF WATER

(part 1 cnidaria) (part 1 cnidaria) (part 2 cnidaria) (part 2 cnidaria) (nematocyst firing) (nematocyst firing) (swimming anemone) (swimming anemone) (fighting anemone) (fighting anemone) (national geographic jellyfish) (national geographic jellyfish) partnership) partnership) BIbzfY comb jellyfish BIbzfY comb jellyfish BIbzfY BIbzfY