Transcript KINGDOM PROTISTA - University of West Alabama

PHYLUM
CNIDARIAN
Outline
• Classification
• Characteristics
• Reproduction
• Description of the 4 classes
• Current experimentation
• Distribution
• Fossil records
Classification
Cnidarian - (Gr. Knide, nettle, + L. aria [pl.
suffix] like or connected with)
 Alternate phylum name is Coelenterate
(Gr. Koilos, hollow, + enteron, gut, + L. ata
[pl. suffix]
 Consist of more than 9000 species
 4 classes
Characteristics of cnidarians
• Aquatic (marine, some
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fresh water)
Body structure (radial or
biradial symmetry)
Gastro vascular cavity
Two layers (epidermis
and gastrodermis)
Nematocysts
Two forms of
cnidarians
1. Polyp (attached)
– live in colonies
2. Medusa (jellyfish)
– Free-swimming
REPRODUCTION
Class Scyphozoan
(Gr. Skyphos, cup)
“The true jellyfish,” can be characterized by a thick,
jelly like bell made up of mesoglea and 95% to 96%
water. Their entire body is covered with
nematocysts, which packs a painful sting. Oral arms
are their primary source for feeding and ingestion.
Reproduction is sexual.
Class Hydrozoa
(Gr. Hydra, water serpent, + zoon, animal)
Mainly marine and live colonial. Consist of an
epidermis, gastrodermis, and mesoglea. Hydras use
a basal disc for movement and secrete mucous for
assistance. The hydra relies on tentacles for feeding
and digestion. They reproduce asexually (budding)
and sexually, usually in Autumn.
Class Anthazoan
(Gr. Anthos, flower, + zoon, animal).
Only exist in the polyp form. Can live solitary as
anemones or in colonies, such as corals. Possess a
gastro vascular cavity subdivided by septa bearing
nematocysts. Reproduction through separate sexes
or asexually by budding, but commonly pedal
laceration
Class Cubozoa
(Gr. Kybos, a cube + zoon, animal).
Size range up to 25 cm tall, but are usually 2 to 3 cm. The
transverse of the bell appears square in these animals. On the
corners of the bell are tentacles these help in moving and
feeding. Reproduce by asexual budding.
Current experimentation
Bioluminescence
Aequorin, composed of
Calcium++activated
photoprotein emits a
blue-green light. This
light is used by
scientists to highlight
genes for quicker
studies.
Distribution
Fungiid Coral from Indonesia
Distribution
• Cnidarians generally occupy two major
niches
• Some use their cnidocysts to trap prey.
Other cnidarians, such as anthozoans
depend on zooxanthellae. These are,
symbiotic dinoflagellates within their
tissues. This is how they survive.
Distribution
• These single-celled protists carry out
photosynthesis within the animal's tissues,
and pass on the carbon compounds they
fix to their hosts; corals, therefore, are
photosynthetic animals in a sense
Distribution
• While not all corals are dependent on symbionts
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— some live at great depths where there is
never light
colonial, reef-forming corals depend on these
symbionts; therefore, reefs can only exist in
shallow water. The white areas on the coral reef
on the next slide show the reefs exposed at low
tide. This loss of symbionts, called bleaching, is
deadly to coral reefs.
Fossil Records
• Cnidarian fossils date back to the time
when animals first appear in the fossil
record, the Vendian. Since then, the fossil
record of cnidarians without mineralized
skeletons is quite sparse, and restricted to
unusual sites with excellent fossil
preservation.
Fossil Records
• Cnidarians which possessed hard skeletons, the corals,
have left a significant legacy of their existence. While a
few mineralized coral-like fossils have turned up in the
Cambrian Period, identifiable corals began an
evolutionary radiation in the Early Ordovician. These
Paleozoic corals included taxa known as tabulate corals,
rugose corals, and heliolitid corals. All these forms were
wiped out at the end of the Permian Period, in a mass
extinction event that claimed something like 95% of all
marine invertebrate species (Foster, 1979)
Fossil Records
• Scleractinian corals first appear in the Middle
Triassic, about 15 milion years after the Permian
extinction. They rapidly expanded into ecological
niches once dominated by tabulate and rugose
corals, and became the dominant hermatypic
(reef-building) organisms in shallow tropical
marine habitats. Because corals are sensitive to
changes in light, temperature, water quality, and
salinity, their fossils provide information that can
be used to interpret climate and geography of
past environments.
Scyphozoa
• All scyphozoa are marine, though a few
fresh water forms have occasionally been
reported.
• While many species live solitary lives,
some like Aurelia may travel in shoals of
hundreds to thousands of individuals
stretching for dozens of kilometers.
Hydrozoans
• Hydrozoans may date back to the Vendian (late
Precambrian), but the fossil record of
hydrozoans is scanty before the Cenozoic,
starting about 65 million years ago. The oldest
fossil milleporines and stylasterines — the "fire
corals," so called from their stony growths that
resemble those of true true corals — appeared
in the Late Cretaceous and are moderately
common as fossils in the Cenozoic
• A rare fossil hydroid, Mississippidendrium
from the Cretaceous of northeast
Mississippi
Anthozoans
• Anthozoans are exclusively marine, polypoid
cnidarians. They occur from the intertidal zone
to the depths of the trenches (to 6000 m). In
excess of 6000 species currently exist (Hyman
1940), comprising about two-thirds of extant
cnidarian species (Dunn 1982); some
anthozoans, such as the scleractinian corals,
have a rich fossil history (Wells and Hill 1956).
Cubozoans
• A few probable cubozoans are known as
fossils from the famous Mazon Creek
locality (Pennsylvanian age) near Chicago,
Illinois
• Other fossils that may be cubozoans have
been found in the Jurassic Solnhofen
Limestone of Bavaria, Germany
Dispersal
• Cnidarians live in aquatic environments and inhabit all
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depths, from the sandy substrate up to the surface.
They can be found from the Great Barrier Reef rising off
the coast of northeastern Australia to the continental
shelves of bone-chilling arctic oceans, and just about
every saltwater marine habitat in between. (national
zoo, 2008)
Some jellyfish are even found in freshwater lakes, such
as the freshwater jellyfish (Craspedacusta sowerbyi),
which haunts several lakes in New Zealand. Not to worry
though, these jellyfish are harmless to humans and feed
mainly on zooplankton (national zoo, 2008)
Figure 1a. Distribution map of 60 species of Chilean sea anemones according to the literature. The two species with
doubtful classification and the species without location are not shown in the distribution map. p: type localities; D: type
locality of synonymous species; : other collection sites; collection sites are connected by lines for greater clarity. NPZ:
North Patagonian Zone, CPZ: Central Patagonian Zone, SPZ: South Patagonian Zone.
Dispersal Patterns
Works Cited
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Conway Morris, S., 1993: The fossil record and early evolution of the Metazoa. --Nature, vol. 361, 21 January, pp.
219-225
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Daly, M, DG Fautin & VA Cappola (2003), Systematics of the Hexacorallia (Cnidaria: Anthozoa). Zool. J. Linn. Soc.
139: 419–437
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Fautin, Daphne G. and Romano, Sandra L. 1997. Cnidaria. Sea anemones, corals, jellyfish, sea pens, hydra.
Version 24 April 1997. http://tolweb.org/Cnidaria/2461/1997.04.24 in The Tree of Life Web Project,
http://tolweb.org/
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Fautin, Daphne G. and Romano, Sandra L. 2000. Anthozoa. Sea Anemones, Corals, Sea Pens. Version 03 October
2000. http://tolweb.org/Anthozoa/17634/2000.10.03 in The Tree of Life Web Project, http://tolweb.org/
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Fautin, D. G. and R. N. Mariscal. 1991. Cnidaria: Anthozoa. Pp. 267-358 in F. W. Harrison and J. A. Westfall
(eds.), Microscopic Anatomy of Invertebrates, volume 2: Placozoa, Porifera, Cnidaria, and Ctenophora. Wiley-Liss,
Inc., New York and other cities.
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Fautin, D. G., Romano, S. L. & Oliver, W. A. Jr., 1999: Zoantharia - Sea Anemones and corals. The Tree of Life
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Fedonkin, Misha A. and Waggoner, Benjamin M. 1997. The Late Precambrian fossil Kimberella is a mollusc-like
bilaterian organism. Nature 388(6645): 868-871
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Foster, Merrill W. 1979. Soft-bodied coelenterates in the Pennsylvanian of Illinois. pp. 191-267 In: Mazon Creek
fossils. edited by Nitecki, Matthew H. Academic Press, New York, NY.
Works cited
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Fundación Huinay, Departamento de Biología Marina, Universidad Austral de Chile Casilla 567, Valdivia, Chile
http://nationalzoo.si.edu/Animals/Invertebrates/Facts/cnidarians/
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Parker, S. P. (ed.), 1982: Synopsis and classification of living organisms. Vols. 1 & 2 --McGrew-Hill Book Company
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Image: http://en.wikipedia.org/wiki/Jellyfish
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Image: www.aloha.com