Nervous System
The box jellyfish is an invertebrate that is part of the animal phylum cnidaria and have a slightly better developed nervous system than other jellyfish. The box jellyfish is also actually one of the most dangerous jellyfish in the sea. Their venom is one of the most deadly in the world and actually attack the heart and the nervous system. Like all jellyfish, the box jellyfish does not have a brain. Instead, they have distributed nervous systems that are distributed throughout the body. These nervous systems have three major neuronal components; the rophalia, the scyphomedusae, and the cubomedusae. The rophalia is the sensory structure and it sets the basic swim motion. The scyphomedusae is the network of neurons that direct muscle contractions. The cubomedusae is the network of neurons that direct tentacle movement. There are two different networks that direct muscle and tentacle movement. With these three, the box jellyfish has a well developed, yet scattered, nervous system.