The structure shown is Cnidoblast or Cnidocytes seen in Coelenterates and hence this phylum is also known as Phylum Cnidaria. These are stinging cells mainly present on the tentacles and also on the body. These cells help in anchorage, capturing the prey and for defense. These cells contain nematocysts which is filled with hypnotoxin (neurotoxin) and a thread is suspended inside the fluid. As any organism rests on the tentacles, the pressure is exerted to the fluid of cnidoblasts due to which the the thread expels out and hypnotoxin depresses the brain activity of the prey or the predator.
