Tangs, or Surgeonfishes, are one of the most commonly encountered reef fishes around all tropical water of the world. They are named after the characteristic scalpel-like spines on the caudal peduncle or posterior portion of the body. Tangs are one of the dominant herbivores of the reef community and play an important role in the overall food chain of the reef ecosystems. While most feed on benthic algae and occur in relatively shallow water, some species such as certain Naso regulary venture to depths of 60m or more and three species of Acanthurus (mata, nubilus, and thompsoni) feed on current-borne zooplankton. Surgeonfishes often feed in schools, sometimes containing hundreds of individuals and often with more than one species involved. This is an effective strategy for overwhelming certain damselfishes that zealously defend their algal gardens against intruders.