Phylum CnidariaPhylum CnidariaA. 2 body formsA. 2 body forms

1. Medusa: jellyfish1. Medusa: jellyfish

a. motilea. motile

b. umbrella shapedb. umbrella shaped

c. tentacles and mouth underneathc. tentacles and mouth underneath

2. Polyp: corals2. Polyp: corals

a. sessilea. sessile

b. tubelikeb. tubelike

c. Tentacles and mouth on topc. Tentacles and mouth on top

B.B. Some cnidarians exist as either a medusa or polyp but many will Some cnidarians exist as either a medusa or polyp but many will alternate between the two during their life cycle. alternate between the two during their life cycle.

C.C. Radial symmetryRadial symmetry

D.D. The unique feature of the Cnidaria is that they have stinging The unique feature of the Cnidaria is that they have stinging cells, called cells, called nematocystsnematocysts. Each of these cells contains a . Each of these cells contains a thread-like sting that is discharged in attack or defensethread-like sting that is discharged in attack or defense. .

E.E. CarnivoresCarnivores

Class Hydrozoa: Hydra

Classs Scyphozoa: Jellyfish

Class Anthozoa: Corals

Class HydrozoaClass Hydrozoa Hydra, Portuguese man-of-warHydra, Portuguese man-of-war No Medusa StageNo Medusa Stage Most are found in lakes, rivers, pondsMost are found in lakes, rivers, ponds Some are Marine; ex: Portuguese man-of-warSome are Marine; ex: Portuguese man-of-war Attach to rocks or other plants through their basal diskAttach to rocks or other plants through their basal disk Brown or whiteBrown or white Move by a tumbling or somersaulting action. (pg 642)Move by a tumbling or somersaulting action. (pg 642) Reproduce: Reproduce:

1. Asexually: budding; Polyps produce buds, they will grow into 1. Asexually: budding; Polyps produce buds, they will grow into aa

new polyp, then they will eventually separate from the oldnew polyp, then they will eventually separate from the old

polyps body and attach polyps body and attach

themselves to rocks or plants and live independently. themselves to rocks or plants and live independently.

Bud

Parent

2. Sexually Reproduction: Mostly marine hydrozoas2. Sexually Reproduction: Mostly marine hydrozoas.. a. The medusas release sperm or eggs into the water. a. The medusas release sperm or eggs into the water. The gametes fuse and produce zygotes that develop into The gametes fuse and produce zygotes that develop into free-swimming larvae (planulae). The planulae will free-swimming larvae (planulae). The planulae will settle and attach to the bottom of the ocean floor and settle and attach to the bottom of the ocean floor and develop into a polyp. Each polyp will produce multiple develop into a polyp. Each polyp will produce multiple buds (called a colony). These buds do not separate from buds (called a colony). These buds do not separate from the body (as it does in asexually reproduction). They will the body (as it does in asexually reproduction). They will stay attached and eventually turn into male and female stay attached and eventually turn into male and female medusas. These medusas will leave the polyps to grow medusas. These medusas will leave the polyps to grow and mature. and mature.

FeedingFeeding When feeding, hydras extend their body to maximum When feeding, hydras extend their body to maximum

length and then slowly extend their tentacles. Despite their length and then slowly extend their tentacles. Despite their simple construction, the tentacles can extend four to five simple construction, the tentacles can extend four to five times the length of the body. Once fully extended, the times the length of the body. Once fully extended, the tentacles are slowly maneuvered around waiting for a tentacles are slowly maneuvered around waiting for a suitable prey animal to touch a tentacle. Once contact has suitable prey animal to touch a tentacle. Once contact has been made, nematocysts on the tentacle fire into the prey been made, nematocysts on the tentacle fire into the prey and the tentacle itself coils around the prey. Within 30 and the tentacle itself coils around the prey. Within 30 seconds, most of the remaining tentacles have already seconds, most of the remaining tentacles have already joined in the attack to control the struggling prey. Within joined in the attack to control the struggling prey. Within two minutes, the tentacles will surround the prey and two minutes, the tentacles will surround the prey and move it into the mouth. Within ten minutes, the prey will move it into the mouth. Within ten minutes, the prey will be enclosed within the gastrovascular cavity and digestion be enclosed within the gastrovascular cavity and digestion will have started. The hydra is able to stretch its body wall will have started. The hydra is able to stretch its body wall considerably in order to digest prey more than twice its considerably in order to digest prey more than twice its size. After two or three days, the undigestible remains of size. After two or three days, the undigestible remains of the prey will be discharged by muscular contraction the prey will be discharged by muscular contraction through the mouth. through the mouth.

Hydra StructureHydra Structure

A: TentacleA: Tentacle

B. Budd/new hydra forming B. Budd/new hydra forming

C. MesogleaC. Mesoglea

D. Basal DiskD. Basal Disk

E. Cnidocyte (stinging cells)E. Cnidocyte (stinging cells)

F. Nematocyst (used for F. Nematocyst (used for defense)defense)

G. Gastrovascular cavity (Help G. Gastrovascular cavity (Help Digest)Digest)

H. Endoderm (inner cell layer)H. Endoderm (inner cell layer)

I. Ectoderm (outer cell layer)I. Ectoderm (outer cell layer)

J. Sperm sacJ. Sperm sac

K. MouthK. Mouth

Class ScyphozoaClass Scyphozoa

JellyfishJellyfish Can range from a thimble to as large as a queen-size Can range from a thimble to as large as a queen-size

mattress. mattress. Feeding: predators; use their tentacles to capture and sting Feeding: predators; use their tentacles to capture and sting

their prey. Their nematocysts can be extremely toxic. their prey. Their nematocysts can be extremely toxic. Reproduction: sexually. Alternation of polyps and medusas Reproduction: sexually. Alternation of polyps and medusas

(as discussed in Hydrozoa)(as discussed in Hydrozoa)

Dominant form is the MedusaDominant form is the Medusa

Moon Jellyfish

Class AnthozoaClass Anthozoa Largest classLargest class Consists of only polyp formConsists of only polyp form Ex: sea anemones, coralEx: sea anemones, coral Reproduce: asexually: budding. Sexually be releasing eggs Reproduce: asexually: budding. Sexually be releasing eggs

and sperm into the ocean where fertilization will occur. and sperm into the ocean where fertilization will occur. Most species live in warm water and they are brightly colored. Most species live in warm water and they are brightly colored. Feeding: They feed on fishes, which are caught by means of Feeding: They feed on fishes, which are caught by means of

the numerous nematocysts in their tentacles. These animals the numerous nematocysts in their tentacles. These animals are known for their symbionts. These include species of fish are known for their symbionts. These include species of fish that actually live among the tentacles of large anemones, that actually live among the tentacles of large anemones, somehow avoiding lethal contact with the nematocysts. Other somehow avoiding lethal contact with the nematocysts. Other anemones have unicellular algae living within their tissues, anemones have unicellular algae living within their tissues, from which they probably derive some nutrition. Yet others from which they probably derive some nutrition. Yet others have a symbiotic relationship with hermit crabs, which gather have a symbiotic relationship with hermit crabs, which gather up the anemones and place them on the snail shells that the up the anemones and place them on the snail shells that the crabs occupy. The anemones benefit from food particles crabs occupy. The anemones benefit from food particles dropped by the crab, and the crab gains protection from dropped by the crab, and the crab gains protection from predators due to the presence of the nematocyst-laden predators due to the presence of the nematocyst-laden anemones. anemones.

Anemonaes

CORAL GRIEF: Global warming isn't just affecting cold areas. Coral reefs are found mainly in warm waters. Tiny animals called coral polyps build the reefs. But if the water gets too warm, the polyps can die. That's already starting to happen at the Great Barrier Reef, Earth's largest coral reef.