Cnidaria&ctenophora

Cnidaria&ctenophora

1. Cnidaria and Ctenophora Presented By Nyeem Hasan - ASH 1819029M Jannatul Fowzia – MUH1819046F Tasnim Sultana – MUH1819034F Farida Yasmin – MUH1819004F

2. Cnidaria Cnidaria means the name of the diploblastic animal which is embryonic organism Ctenophera Ctenopheras are fairly simple invertival animals that live in marine water.

3. Characteristics Cnidaria Stinging cells. Two stages in life cycle (polyp & medusa ) Radial symmetry. Diploblastic. Presence of Nematocyst. Contain incomplete digestive system. Ctenophora Adhesive cells. One stage of life cycle; only medulla. Bi-radial symmetry. Diploblastic. Absence of Nematocyst. Complete digestive system.

4. Classification of Ctenophora 1 Tentaculata : They have tentacles and small stomodaeum. Examples: Hormiphora (The Sea Walnut), Pleurobrachia (The Sea gooseberry). Ctenoplana , Cestum (The Venus’ Girdle). 2 Nuda : Their body is without tentacles. They has spaceous mouth and stomodaeum. Example: Beroe .

5. Importance of Ctenophora  Since Ctenophora reproduce quickly and are good predators, they can easily bring down an ecosystem where they have no predators . Ctenophores have left a poor fossil record. Nearly all ctenophores are bioluminescence. They give off excess energy in the form of light instead of heat. There are more than 100 varieties of ctenophore spread through out the worlds, which form a considerable proportion of the entire plankton biomass.

6. Classification of cnidaria Hydrozoa Individuals are either exclusively poly­ploid or medusoid or constituted by both forms in the life cycle. Examples: Hydra , Obelia . Anthozoa Appear like plants but are animals. Medula stage is dominating. Examples : Coral , Helipara . Scyphozoa Generally refered to as jellies. Polyp stage is dominating. Example: Aurelia, Pilema

7. Nematocysts Cnidaria have stinging cells called cnidocytes . Cnidocytes contain large organelles called (a) nematocysts that store a coiled thread and barb, the nematocyst. When the hairlike cnidocil on the cell surface is touched, even lightly, ( b) the thread, barb, and a toxin are fired from the organelle.

8. Reproduction of Hydra There are two types of reproduction process in hydra. Sexual Reproduction Asexual Reproduction

9. Jellyfish life cycle Jellyfish have a stalked (polyp) phase, when they are attached to coastal reefs, and a jellyfish (medusa) phase, when they float among the plankton . The medusa is the reproductive stage; their eggs are fertilised internally and develop into free-swimming planula larvae. After a brief period floating about in surface waters, the larvae settle to the sea floor, attaching themselves at one end. There they develop into polyps and begin to feed and grow . In spring, some of the polyps start to bud off immature jellyfish known as ephyra larvae and then these grow into mature jellyfish.

10. Importance of Cnidiaria Coral reefs provide food and shelter for thousands of species Reefs protect the land from ocean waves Filter and clean the water From symbiotic relationship with other ocean life. Scientist have discovered many chemical compounds and other illness

11. REFERENCE https:// ctenophoras.weebly.com/importance.htm https ://en.wikipedia.org/wiki/Hydra_(genus ) https://opentextbc.ca/biology2eopenstax/chapter/phylum-cnidaria / http:// www.ucmp.berkeley.edu/cnidaria/ctenophora.html http://www.notesonzoology.com/phylum-ctenophora/ctenophora-and-cnidaria-similarities-and-dissimilarities-zoology/5829