An Introduction to the Phylum

Cnidaria & NematodaInvertebrates

Stages of a Cnidarian

1-Polyp

2- Medusa

IMAGE LOCATION: http://www.mesa.edu.au/friends/seashores/cnidaria.html

Anatomy

Characteristics of Cnidarians-Nematocysts- small organelles

used to capture prey and ward off predators, located on the tentacles-Radially symmetrical-Sexual Production in Medusae, Asexual Budding in Polyps

CNIDARIANS

Anthozoa

Hydrozoa

Scyphozoa

Three Major Types

#1- AnthozoaInclude the corals that build great

reefs in tropical

waters, as well as sea anemones,

sea fans, and sea pens.

IMAGE LOCATION: http://tolweb.org/Anthozoa

The oldest anthozoans

are probably

the polyp-like and sea

pen-like fossils from the Vendian

(late Precambrian) period.

Most hydrozoans switch between a polyp and a medusa stage, but they spend part of their lives as "jellyfish,” and they are predatory

Dioecious and colonial

#2-Hydrozoa

IMAGE LOCATION: http://www.freeweb.hu/tarrdaniel/images/hydrozoa.htm

#3- ScyphozoaDespite their large size, jellyfish have no head, no skeleton, and no special organs for respiration or excretion. Their life cycle involves an alternation between polyp phase and a medusa stage, though the medusa stage usually predominates.

IMAGES LOCATION: http://www.ucmp.berkeley.edu/cnidaria/scyphozoamm.html

Cubozoa

They appear cubic from

above, and have four evenly spaced out tentacles or bunches of

tentacles and well-developed

eyes.IMAGE LOCATION: http://www.ucmp.berkeley.edu/cnidaria/cubozoa.html

Arguably, Cubozoans are

a 4th group

Additional FactsOn Cnidarians

Cnidarians have a single orifice and

body cavity used for digestion and respiration.

Most cnidarians prey on organisms from plankton to animals larger than themselves, however most

obtain much of their nutrition from endosymbiotic algae, and some are

parasitic.

Cnidarians make up corals - found in warm, shallow marine waters - other cnidarians live in the depths, in polar seas and in freshwater.

NematodaRoundworms

-HABITAT

-BODY STRUCTURE

-SYSTEMS AND REPRODUCTION

IMAGE LOCATIONS: http://en.wikipedia.org/wiki/Nematodahttp://www.ucmp.berkeley.edu/phyla/ecdysozoa/nematoda.html

HabitatNematodes inhabit nearly every geographic location on Earth

Can live in extreme habitats

Can be parasitic

Found in soil and sediments

Some can parasitize humans

And Interaction With Humans

Body StructurePseudocoelemates

Tough, Covered with transparent

cuticle, cylindrical,

unsegmented body,pointy

posterior,blunt anterior

end,bilaterally

symmetrical

Systems and

Reproduction

Complete digestive system

No circulatory system

Sexual Reproduction

Has a nervous system

SOURCES http://www.mesa.edu.au/friends/seashores/cnidaria.html

http://tolweb.org/Anthozoa

http://www.ucmp.berkeley.edu/cnidaria/cubozoa.html

http://www.freeweb.hu/tarrdaniel/images/hydrozoa.htm

http://www.ucmp.berkeley.edu/cnidaria/scyphozoamm.html

http://www.ucmp.berkeley.edu/phyla/ecdysozoa/nematoda.html

http://www.earthlife.net/inverts/nematoda.html

http://ucmp.berkeley.edu/phyla/ecdysozoa/nematoda.html