Siphonophores are predatory carnivores. Their diets consist of a variety of copepods, small crustaceans, and small fish. Generally, the diets of strong swimming siphonophores consist of smaller prey, and the diets of weak swimming siphonophores consist of larger prey. A majority of siphonophores have gastrozooids that have a characteristic tentacle attached to the base of the zooid. This structural feature functions in assisting the organisms in catching prey. Species with large gastrozooids are capable of consuming a broad range of prey sizes. Similar to many other organisms in the phylum of Cnidaria, many siphonophore species exhibit nematocyst stinging capsules on branches of their tentacles called tentilla. The nematocysts are arranged in dense batteries on the side of the tentilla. When the siphonophore encounters potential prey, their tentillum react to where the tentacles create a net by transforming their shape around the prey. The nematocysts then shoot millions of paralyzing, and sometimes fatal, toxin molecules at the trapped prey which is then transferred to the proper location for digestion. Some species of siphonophores use aggressive mimicry by using bioluminescent light so the prey would not properly identify the predator.