Question

A brief explanation of phylum cnideria ?​

Answer 1

$\bigstar\:\underline{\boxed{\bf{\red{Phylum\:Cnideria :}}}}$

• They have tissue level of organisation and are diploblastic.
• Body and tentacles have peculiar stinging cells called as Cnidoblasts (nematoblasta).
• A nematoblast has nematocysts (stinging oragans).
• These are used for adhesion, food capture, ogfence and defense.
• A ventral gastrovascular cavity or coelenteron with a single opening, mouth. Thus, there is present incomplete digestive tract. Both intra and extra cellular digestion present.
• Colonial forms show two main types og individuals or zooids : polyps and medusa.
• The cnidarians which exist in both the forms exhibit metagenesis, i.e., polyps (attached form) peoduce medusae (free-swimming form) asexually and medusae form the polyps sexually (e.g., Obelia)

Examples :

▪ Physalia (portugese man of war)

▪ Adamsia (sea anemone)

▪ Pebnatula (sea pen)