Whale Shark Essay

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Introduction One particularly interesting sea creature is the whale shark, formally known as Rhincondon typus it was first discovered in 1828 by Andrew Smith (Rowat 2012). This large fish is found globally in warm tropical oceans and prefers to stay within 200 meters of the ocean’s surface in waters ranging from 4.2 to 28.7 degrees Celsius (Stevens 2006). This creature can be found all across the globe in any warm tropical seas. Aggregations of whale sharks have been seen off the coast of Australia at times, although it is primarily a creature of solitude. Whale sharks are filter feeders that consume plankton as well as small fish and are harmless to humans. The whale shark is a species with a fascinating ecology, life history, behavior, anatomy
Its body and dorsal surfaces have patterns of light spots and stripes over a dark blue background. The whale shark’s length ranges from 12 meters up to 20 meters on average. Females typically grow to be bigger than the males and weigh anywhere from 47,000lbs to 66,000lbs as adults. It is estimated that this species average lifespan is around 70 years, though accurately measurements have proven difficult (Stevens 2006). Rhincondon typus is known to be primarily a loner traveling by itself the majority of the time, although they are known to seasonally aggregate in specific areas.
Life cycle Due to the large expanse and sheer size of the whale shark much of the species lifecycle is unknown. Although in recent years some aquariums have created exhibits large enough to contain the whale shark enabling more thorough research. It is largely speculated that the ratio of male to female whale sharks dictate the structure of their mating system (Martin 2007). Rhincodon typus are oviparous giving birth to live young and have been documented to carry up to 300 embryos at one time. Female whale shark’s will give birth to numerous batches of pups in short succession and may rest up to a year after giving birth before mating again. The large size of the litter and rate of birth suggests a very high rate of neonatal mortality. Young pups will stay with their mother for an undetermined amount of time until they are
At maturity males are typically close to nine meters in length with the females being slightly larger. Throughout its adult life the whale shark is mostly solitary traveling alone and staying to itself. Due to the size of it doesn’t have many predators though on occasions killer whales have been known to attack Rhincodon typus (Rowat 2012).
Structure and Function The lorenzini is a pit-like organ located on the head of the whale shark that senses weak electrical and magnetic fields. This is an area that is currently being researched extensively and is largely unknown. It is speculated that this organ is used by the whale shark as a navigational aid through using the earth’s magnetic force (Rowat 2012).
Evolution
Studying the evolutionary history and adaption for this species is difficult and an ongoing struggle for scientists. It is classified in the order of Chondrichthyes suborder Elasmobranchii and family of Rhincodontidea. The difficulty in tracing this species evolutionary history stems from the fact that its ancestry dates back 245 million year ago to the Jurassic and Cretaceous

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