Nerve net Nerve net A nerve net consists of interconnected neurons lacking a brain or any form of cephalization. While organisms with bilateral body symmetry are normally associated with a central nervous system, organisms with radial symmetry are associated with nerve nets. Nerve nets can be found in members of the Cnidaria, Ctenophora, and Echinodermata phyla, all of which are found in marine environments. Nerve nets can provide animals with the ability to sense objects through the use of the sensory neurons within the nerve net. The nerve net is the simplest form of a nervous system found in multicellular organisms. Unlike
Venom Other insects, such as true bugs and many ants, also produce venom. At least one ant species ("Polyrhachis dives") has been shown to use venom topically for the sterilisation of pathogens. There are venomous invertebrates in several phyla, including jellyfish such as the dangerous box jellyfish and sea anemones among the Cnidaria, sea urchins among the Echinodermata, and cone snails and cephalopods including octopuses among the Molluscs. Venom is found in some 200 cartilaginous fishes, including stingrays, sharks, and chimaeras; the catfishes (about 1000 venomous species); and 11 clades of spiny-rayed fishes (Acanthomorpha), containing the scorpionfishes (over 300 species), stonefishes