Jellyfish canal. Cilia in these canals circulate the fluid in a regular direction. The box jellyfish is largely similar in structure. It has a squarish, box-like bell from each of the four lower corners of which hang a short pedalium or stalk which bears one or more long, slender tentacles. The rim of the bell is folded inwards to form a shelf known as a velarium which restricts the bell's aperture and creates a powerful jet when the bell pulsates, allowing box jellyfish to swim faster than true jellyfish. Hydrozoans are also similar, usually with just four tentacles at the edge
Jellyfish as food coastal areas have been utilized as a source of food and ingredient in Chinese cuisine for over 1,700 years. Cannonball jellyfish ("Stomolophus meleagris") and jelly blubber ("Catostylus mosaicus") are edible species of jellyfish. When live, the cannonball jellyfish contains toxins that can cause cardiac problems in animals (including humans). "Rhopilema esculentum" and "Rhopilema hispidium" are edible jellyfish, and are the most common ones consumed in China, Japan and Korea. Additional edible jellyfish species include "Aurelia aurita", "C. orsini", "Dactylometra pacifica", "Hispidium spp.", "Lobonema smithi", "Lobonemoides gracilis" and Nomura's jellyfish ("Stomolophus nomuria"). Desalted ready-to-use jellyfish are low in calories and contain