Describe the structure and function of nematocysts. Solution Nematocysts are protective capsules found in the phylum Cnidaria(jelly fish, sea anemone etc) produced by specialised cells called cnidoblast.Upon proper stimulation (chemical or mechanical) a hollow thread like structure pops aside this stinging structure is used to poison or kill prey.Cnidocyls are sensory structure present in the cnidoblast which triggers the release of nematocysts through an operculum. Cnidarians are invertebrates they use a hydrostatic skeleton.Cnidocytes can be used once and constantly replaced. 4types nematocysts are present Penetrant:it penetrates the target and release toxins; used for defence Volvent:it wraps around the target Large and small Glutinant : use sticky fibres called velcro to attack target.