Introduction A particularly interesting marine creature is the whale shark, formally known as the Rhincondon typus and was first discovered in 1828 by Andrew Smith (Rowat 2012). This large fish is found worldwide in warm tropical oceans and prefers to remain within 200 meters of the ocean surface in waters ranging from 4.2 to 28.7 degrees Celsius (Stevens 2006). This creature can be found worldwide in all warm tropical seas. Aggregates of whale sharks have occasionally been sighted off the coast of Australia, although they are primarily a solitary creature. Whale sharks are filter feeders that consume plankton and small fish and are harmless to humans. The whale shark is a species with a fascinating ecology, life history, behavior and anatomy. Its body and dorsal surfaces have patterns of bright spots and stripes on a dark blue background. The length of the whale shark varies on average from 12 meters up to 20 meters. Females typically grow larger than males and weigh 47,000 pounds to 66,000 pounds as adults. The average lifespan of this species is estimated to be approximately 70 years, although accurate measurements have proven difficult (Stevens 2006). The Rhincondon typus is known to be primarily a loner that travels alone most of the time, although they have been known to aggregate seasonally in specific areas. Life cycle Due to the large expanse and size of the whale shark, much of the species' life cycle is unknown. Although in recent years some aquariums have created exhibits large enough to contain the whale shark allowing for more in-depth research. It is largely assumed that the ratio of male to female whale sharks determines the structure of their mating system (Martin 2007). Rhincodon typus are oviparous and give birth to live young and have been documented carrying up to 300 embryos at one time. Female whale sharks give birth to numerous batches of pups in short succession and can rest for up to a year after giving birth before mating again. The large size of the litter and the birth rate suggest a very high rate of neonatal mortality. The young cubs will remain with their mother for an indeterminate period of time until they reach maturity. At maturity males are typically close to nine meters in length while females are slightly larger. Throughout its adult life the whale shark is mostly solitary, traveling alone and staying aloof. Due to its size it does not have many predators, although killer whales have been known to attack Rhincodon typus on occasion (Rowat 2012). Structure and function The lorenzini is a pit-shaped organ located on the whale shark's head that senses weak electric and magnetic fields. This is an area that is currently being extensively researched and is largely unknown. It is hypothesized that this organ is used by the whale shark as an aid to navigation through the use of the Earth's magnetic force (Rowat 2012). Evolution Studying the evolutionary history and adaptation of this species is difficult and an ongoing struggle for scientists. It is classified in the order Chondrichthyes, suborder Elasmobranchii and in the family Rhincodontidea. The difficulty in reconstructing the evolutionary history of this species derives from the fact that its ancestors date back 245 million years ago, to the Jurassic and Cretaceous periods.