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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