Alternation of generation in cnideria

ALTERNATION OF GENERATION IN CNIDERIA

1. PRESENTATION : ALTERNATION OF GENERATION IN CNIDERIA

2. Alternation of generation is also known as metagenesis . The phenomenon in which asexually repruducing polyp alternates which sexually rèproducing medusa in called alternation of generation. Alternation of generation in cnideria

3. There are two body forms in the life history of most cnidarians. These are Polyp Modusa

4. The polyp is usually asexual. It is sessile. It attaches to a substrate at the aboral end. It has a cylindrical body, called the column. lt has mouth surrounded by food gathering tentacles. POLYP

5. 2 ) Medusa (Plural Medusae ) It is a sexual. It is dioecious . It is free-swimming. Its shape is an inverted bowl Tentacles are on its margins. The mouth openings is centrally located lacing downward. .

6. Alternation of generation: In Alternation generation of cniderian the asexual polyp produce male or female medusa , as a result sexual reproduction form zygote which transformers into planula larvae which fix itself to a substrate and finally form a new asexual polyps.