Based on the category in which your question is posted, I supposed you are inquiring as to the loudest animal in the world.
Blue Whales are not only the largest animals alive, but they are the loudest as well. To get an idea of how loud they are, there are a few basic comparisons in decibels. A normal conversation between two people is between 60 and 70 decibels. That's not very loud, considering the human ear's threshold for pain is between 120 and 130 decibels. A jet engine runs about 140 decibels, while Rock Music peaks at 150 decibels. Quite loud. However, the Blue Whale is even louder. The Blue Whales call can reach up to 188 decibels.
"Blue Whales mostly emit very loud, highly structured, repetitive low-frequency rumbling sounds that can travel for many miles underwater. These songs may be used for communicating with others Blue Whales, especially in order to attract and find mates" (EnchantedLearning, 1996-2009).
EnchantedLearning.com (1996-2009). Blue whale, the loudest animal on earth. Retrieved on February 10, 2010 from http://www.enchantedlearning.com/subjects/whales/species/bluewhale/Loudest.shtml.
shrimp
The Demented Shrimp
The blue whale
Cricket
Howler Monkeys.
A dorado
The Howler Monkey.
A Great White shark
The Oyster toadfish, found on the Atlantic coast of North America, is known to be one of the noisiest fish in the world. It produces loud grunting sounds by vibrating its swim bladder, which it uses to attract mates and establish territories.
The correct spelling is "noisiest" (making or accompanied by a lot of noise).
single unicellular creature
a Caribbean sea creature