Phylum CnidariaPhylum Cnidaria

Phylum CnidariaPhylum Cnidaria

Cnidarians have special stinging cells Cnidarians have special stinging cells called cnidocytes. They have long called cnidocytes. They have long flexible tentacles and usually live in flexible tentacles and usually live in sea water. Because they have a sea water. Because they have a hollow gut called a__________, they hollow gut called a__________, they are known as ____________ as well as are known as ____________ as well as Cnidarians.Cnidarians.

Phylum CnidariaPhylum Cnidaria

Characteristics of CnidariansCharacteristics of Cnidarians Body planBody plan Two cell layersTwo cell layers Specialized structuresSpecialized structures Nerve netNerve net Sexual and asexual reproductionSexual and asexual reproduction

Phylum CnidariaPhylum Cnidaria

Body PlanBody Plan Cnidarians generally have _______ Cnidarians generally have _______

symmetry. symmetry.

Phylum CnidariaPhylum Cnidaria

Body PlanBody Plan Cnidarians live in the ocean and can Cnidarians live in the ocean and can

have one of two different body plans:have one of two different body plans:1.1. _______– free swimming_______– free swimming

2.2. ______- sessile______- sessile

Phylum CnidariaPhylum Cnidaria

Two Cell LayersTwo Cell Layers Cnidarians are advanced beyond Cnidarians are advanced beyond

sponges in the development of their sponges in the development of their cell layers. Although sponges also cell layers. Although sponges also have two cell layers, in cnidarians the have two cell layers, in cnidarians the cell layers are organized into ______. cell layers are organized into ______. These tissues have specific functions These tissues have specific functions and serve specific purposes.and serve specific purposes.

Phylum CnidariaPhylum CnidariaTwo Cell LayersTwo Cell LayersA jelly-like substance, the__________, separates the A jelly-like substance, the__________, separates the

two cell layers. The three together make up a two cell layers. The three together make up a body wall called a _____________cavity that body wall called a _____________cavity that surrounds a central cavity.surrounds a central cavity.

Phylum CnidariaPhylum Cnidaria

Specialized StructuresSpecialized Structures

Cnidarians are aggressive hunters for Cnidarians are aggressive hunters for food. They have strong _________ food. They have strong _________ cells which shorten and lengthen to cells which shorten and lengthen to allow _________ of the organism. This allow _________ of the organism. This movement allows the tentacles to movement allows the tentacles to capture food and allows the cnidarian capture food and allows the cnidarian to swim and actively seek prey.to swim and actively seek prey.

Phylum CnidariaPhylum CnidariaSpecialized StructuresSpecialized StructuresCnidarians also have specialized stinging Cnidarians also have specialized stinging

cells called _________. Cnidocytes contain a cells called _________. Cnidocytes contain a coiled protein strand called a __________. coiled protein strand called a __________. The strand has poison barbs or spines on The strand has poison barbs or spines on it.it.

Phylum CnidariaPhylum Cnidaria

Specialized StructuresSpecialized Structures

When Cnidarians encounter prey, the When Cnidarians encounter prey, the cnidocyte fires the nematocyst. The cnidocyte fires the nematocyst. The poison on the barb of the nematocyst poison on the barb of the nematocyst paralyzes or kills the prey. The paralyzes or kills the prey. The Cnidarian then draws the strand back Cnidarian then draws the strand back in and hauls the prey in to be in and hauls the prey in to be digested.digested.

Phylum CnidariaPhylum Cnidaria

Nerve NetNerve Net Cnidarians lack a sophisticated Cnidarians lack a sophisticated

nervous system but possess a nervous system but possess a

________. Nerve nets are ________. Nerve nets are

considered to be the_______considered to be the_______

form of a nervous system.form of a nervous system.

Phylum CnidariaPhylum Cnidaria

Nerve NetNerve Net Nerve impulses cause cell Nerve impulses cause cell

contractions, but no center for contractions, but no center for control exists with a nerve net. There control exists with a nerve net. There is _______ or central nervous system is _______ or central nervous system in cnidarians.in cnidarians.

Phylum CnidariaPhylum CnidariaSexual and Asexual ReproductionSexual and Asexual ReproductionSexual reproduction in the common jellyfishSexual reproduction in the common jellyfish 1. The adult female medusa (free-1. The adult female medusa (free-

swimming form) releases ____ into the swimming form) releases ____ into the water. The adult male medusa releases water. The adult male medusa releases ______ into the water. Fertilization is ______ into the water. Fertilization is _______._______.

Phylum CnidariaPhylum CnidariaSexual and Asexual ReproductionSexual and Asexual Reproduction 2. Fertilization results in formation of 2. Fertilization results in formation of

a ________. This stage is sometimes a ________. This stage is sometimes called the larva or _______. The called the larva or _______. The planula is free-swimming due to the planula is free-swimming due to the presence of cilia.presence of cilia.

Phylum CnidariaPhylum CnidariaSexual and Asexual ReproductionSexual and Asexual Reproduction 3. The planula settles to the ocean floor or any 3. The planula settles to the ocean floor or any

sturdy surface and develops into a sessile stage sturdy surface and develops into a sessile stage called the ________.called the ________.

4. The polyp matures by developing a ________ 4. The polyp matures by developing a ________ and __________. As it grows, layers of __________ and __________. As it grows, layers of __________ form inside the ring of tentacles.form inside the ring of tentacles.

Phylum CnidariaPhylum CnidariaSexual and Asexual ReproductionSexual and Asexual Reproduction

5. Medusa _______ and swim off in the 5. Medusa _______ and swim off in the water to mature and release more water to mature and release more eggs and sperm.eggs and sperm.

Phylum CnidariaPhylum CnidariaSexual and Asexual ReproductionSexual and Asexual ReproductionAsexual Reproduction in CnidariansAsexual Reproduction in Cnidarians Asexual reproduction is usually by Asexual reproduction is usually by

_______. Hydra reproduce in this _______. Hydra reproduce in this

manner. Small buds are formed on the manner. Small buds are formed on the

exterior of their body.exterior of their body. The buds grow, mature within a few The buds grow, mature within a few

_____, and fall off the adult form. They _____, and fall off the adult form. They

then begin life as independent new then begin life as independent new

individuals.individuals.

Phylum CnidariaPhylum CnidariaClasses of CnidariansClasses of Cnidarians

1. Class Hydrozoa1. Class Hydrozoa

These include the _____ and the obelia.These include the _____ and the obelia.

Phylum CnidariaPhylum CnidariaClasses of CnidariansClasses of Cnidarians

2. Class Scyphozoa2. Class Scyphozoa

This class is composed of ________. The This class is composed of ________. The _______ is the dominant body form._______ is the dominant body form.

Phylum CnidariaPhylum CnidariaClasses of CnidariansClasses of Cnidarians3. Class Anthozoa3. Class Anthozoa____________ and _______ compose Class Anthozoa. ____________ and _______ compose Class Anthozoa.

The _______ is the only body form present. Polyps The _______ is the only body form present. Polyps grow as solitary individuals or in colonies.grow as solitary individuals or in colonies.