AIIMS 2013 Biology Question Paper for free online practice with solutions

Stinging cells (cnidocytes or cnidoblasts or nematoblasts) are used for offence and defence. These have nematocysts (the stinging organs), composed of capsule, shaft and thread tube. The thread tube coils around the prey or attaches to it or injects a toxin, called hypnotoxin which paralyzes the victim. They are found in cnidarians- sea pen (Pcnnatnla), sea fan (Gorgonid), etc.