Cnidaria

1
Cnidaria Ctenophora
(Permission granted from University of California
Museum of Paleontology.)

• Michael Ulizio

2
Common and Scientific Names

• Cnidarians Phylum in the kingdom Eumetazoa.
• Four Cnidarian classes
• Hydrozoa - Hydroids. Includes genus Hydra.
• Scyphozoa - Jellyfish.
• Cubozoa - Box Jellyfish.
• Anthozoa - Sea Anemones and Corals.
• Ctenophores Smaller Phylum - Comb Jellies

Picture from Cnidaria and Ctenophora  Second
Edition.
3
Fundamental Biology

• Cnidarians
• Carnivores which trap their prey.
• Some suspension feeders.
• Some supplement food intake with photosynthetic
  symbiotic algae which produces coral.
• Two life stages.
• Polyp stage (Colonial) - asexual reproduction by
  budding.
• Medusa stage Sexual Reproduction.
• Both stages are diploid.

Picture from Cnidaria and Ctenophora  Second
Edition. 

• Ctenophores
• Carnivorous.
• Trap prey like Cnidarians
• Usually feed on plankton
• Most hermaphroditic. (One organism creates
  both the eggs and sperm.)

4
Features Shared with Closely Related Taxa

• Invertebrate classification is undergoing a
  reevaluation
• - Organization of phyla by body plan
• - Organization of phyla by rRNA analysis. 
• Both are similar to Aceolmates, Pseudocoelomates
  and Coelomates in that they all have tissues.
• Both are similar to Echinoderms because they both
  have radial symmetry. 

Picture from Cnidaria and Ctenophora  Second
Edition. 

• Radiata, Bilateria, and Parazoa
• - all multicellular
• - all stem from a hypothesized ancestral protist

5
Different/Unique Features When Compared to
Related Taxa

• Unique Cnidarians
• -have a medusa and a polyp stage
• -Some such as corals and sea anemones only have
  the polyp stage
• stinging cells ingested with food and eliminated
  through various pathways

Picture from Cnidaria and Ctenophora  Second
Edition. 

• Nervous system - manner in which the cells
  grow and spread out within the organism 
• No difference between Axons and Dendrites in
  hydra (also Ctenophora)

6
Importance of Cnidaria Ctenophora

• Blooms of jellyfish
• -yearly problem to fishermen and coastal
  residents
• -can destroy fisheries by consuming fish larvae
  and eating all of the shrimp and plankton (the
  same food the fish need to survive)
• New discoveries of jellyfish
• - April 2004 - new jellyfish was discovered with
  no tentacles
• -Instead of tentacles, the jelly had clusters of
  stinging cells across its body

Picture from Cnidaria and Ctenophora  Second
Edition.
7
Other Important Features

• Marine Medicine
• use of coastal areas for scuba diving, surfing,
  snorkeling, etc. has increased
• risk of humans coming into contact with harmful
  marine life
• this new field is becoming a responsibility of
  family physicians
• patients suffer trauma, envenomation, or
  poisoning from marine creatures.
• Serious Dangers
• Jellyfish poison can also create problems with
  the heart tissue of humans if they are stung. 
• This creates oxygen deprived regions of the
  heart, which can lead to various complications

Picture from Cnidaria and Ctenophora  Second
Edition.
8
Interesting Facts

• Jellyfish can have up to 800 tentacles
• Jellyfish have been on Earth for 450 million
  years
• A coral reef can contain over 1500 types of fish
• The Great Barrier Reef is the only natural
  structure able to be seen from space
• It takes about 20 years for Coral to grow one foot