Classes of Cnidirians

Classes of Cnidirians

4 Classes - Hydroza (Hydroids)

- Scyphozoa (Jellyfish) - Cubozoa (Box Jellyfish)- Anthozoa (Anemones and corals)

Classes of Cnidirians

Class Hydrozoa (Hydroids) • 2700 species • Have both Polyp and Medusa stages • Most are Marine and Colonial • Some are Bioluminescent• Well know fresh water species is the Hydra

(has no medusa stage and exist only as a polyp)

Classes of Cnidirians

Class Hydrozoa (Hydroids)

Classes of Cnidirians

Class Scyphozoa (The Jellyfish)• 200 species • Transparent and Translucent marine organisms • Orange, Pink and Blue in color • Spend most of life floating near surface• Medusa stage is dominant, larger and more

complex that polyp stage• Medusa are bell shaped with hanging tentacles

Classes of Cnidirians

Classes of Cnidirians

Class Scyphozoa (The Jellyfish)• Have separate male and female individuals.• After fertilization planulae form and then

attach and develop into polyps. The polyps can reproduce asexually or bud off the medusa

Classes of Cnidirians

Classes of Cnidirians

Class Cubozoa ( The Box Jellyfish)• Once considered a scyphozoa • Box shaped medusa • Polyp stage is inconspicuous and little known • Tentacles are at each corner of the box• A box jellies sting has been known to be fatal

to humans in some cases

Classes of Cnidirians

Classes of Cnidirians Class Anthozoa (The Sea Anemones and Corlas)• Largest class of cniderians.• “Flower Animals”• 6200 species • Solitary or Colonial marine species • Include stone like corals or soft bodied sea

anemones• Use tentacles for feeding • Almost all live in shallow water and harbor a

symbiotic algae

Classes of Cnidirians

The Ctenophores (Comb Jellies)• Spherical and ribbon like and are known as comb jellies or sea

walnuts • Roughly 90 known are related to the cnidirians • Structurally more complex • They have anal pores • Abundant in the open ocean and are only a few centimeters

long • Propel themselves with 8 comblike plates of fused cilia • Many are Bioluminescent

Classes of Cnidirians

Classes of Cnidirians