where are the stinging cells located on a jellyfish
Jellyfish Most jellyfish do not have specialized digestive, osmoregulatory, central nervous, respiratory, or circulatory systems. The manubrium is a stalk-like structure hanging down from the centre of the underside, often surrounded by oral arms, which connects with the mouth/anus at the base of the bell.[20] This opens into the gastrovascular cavity, where digestion takes place and nutrients are absorbed. It is joined to the radial canals which extend to the margin of the bell, where tentacles are attached.[21] Nematocysts, which deliver the sting, are located mostly on the tentacles; scyphozoans also have them around the mouth and stomach.[22] Jellyfish do not need a respiratory system since their skin is thin enough that the body is oxygenated by diffusion. They have limited control over movement, but can use their hydrostatic skeleton to navigate through contraction-pulsations of the bell-like body; some species actively swim most of the time, while others are mostly passive.[23] Depending on the species, the body contains between 95 and 98% water.[24] Most of the umbrella mass is a gelatinous material — the jelly — called mesoglea which is surrounded by two layers of protective skin. The top layer is called the epidermis, and the inner layer is referred to as gastrodermis, which lines the gut.
Central nervous system The central nervous system (CNS) is the part of the nervous system consisting of the brain and spinal cord. The central nervous system is so named because it integrates information it receives from, and coordinates and influences the activity of, all parts of the bodies of bilaterally symmetric animals—that is, all multicellular animals except sponges and radially symmetric animals such as jellyfish—and it contains the majority of the nervous system. Many consider the retina[2] and the optic nerve (cranial nerve II),[3][4] as well as the olfactory nerves (cranial nerve I) and olfactory epithelium[5] as parts of the CNS, synapsing directly on brain tissue without intermediate ganglia. As such, the olfactory epithelium is the only central nervous tissue in direct contact with the environment, which opens up for therapeutic treatments. [5] The CNS is contained within the dorsal body cavity, with the brain housed in the cranial cavity and the spinal cord in the spinal canal. In vertebrates, the brain is protected by the skull, while the spinal cord is protected by the vertebrae.[6] The brain and spinal cord are both enclosed in the meninges.[6] In central nervous systems, the interneuronal space is filled with a large amount of supporting non-nervous cells called neuroglial cells.