Blast from the Past: Living Fossils
When the goblin shark species was first discovered off the coast of Japan in 1898, it set off a case of scientific déjà vu. Researchers realized that they had seen goblin sharks before -- not swimming in the seas, but in fossil remains. Shark fossils from the Scapanorhynchus species dating back more than 100 million years bore striking resemblance to the goblin shark [source: Bright]. Since the species was thought to be extinct, goblin sharks are now classified as living fossils.
A comparison between the current incarnation and fossils also revealed that little about the fish has changed over time [source: Carwadine]. Despite its ugliness, the goblin shark's body structure seems to have been perfected for survival.
For starters, its flat snout is lined with openings called ampullae of Lorenzini that serve as electrical sensors that track down food. Sharks have a unique sense called electroreception. Ampullae pick up weak electrical impulses living fish and animals give off whenever a muscle contracts. This built-in homing device allows goblin sharks to seek out food. Once it's tracked down a meal, the goblin shark's retractable jaw provides the quick-draw action to snatch up food.
In spite of the goblin shark's large size, it can sneak up on prey effectively thanks to its liver (of all things). In relation to body size, the goblin shark's oily liver takes up enough room on its insides to make it almost as dense as water [source: Ebert]. Since it floats so easily, the fish requires little movement to get around, and it can discretely float up to its desired food source.
Research conducted on the small number of goblin sharks that have come out of the water suggest that their main food sources include fish, shrimp and squid [source: Food and Agriculture Organization of the United Nations]. Deciphering more concrete dietary information has been a challenge since many of the goblin sharks examined have empty stomachs. For example, in one large-scale study on goblin sharks performed in 2006, 29 percent of the 148 individual fish studied had no food inside of them [source: Yano et al].
The last goblin shark sighting occurred in 2007 in Tokyo Bay, Japan [source: Mehta]. After one day in captivity, the living fossil fish died. Since opportunities like that one are few and far between, it may be a long time before we decode all the mysteries of the goblin shark. For more shark-related information, visit the links below.
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More Great Links
- Bright, Michael. "The Private Life of the Sharks: The Truth Behind the Myth." Stackpole Books. 2000. (May 14, 2008)http://books.google.com/books?id=w31fF5IlqdoC
- Carwadine, Mark. "Shark." Firefly Books. 2004. (May 14, 2008)http://books.google.com/books?id=Qh44RNa5yh0C
- Ebert, David A. "Sharks, Rays and Chimaeras of California." University of California Press. 2003. (May 14, 2008)http://books.google.com/books?id=1SjtuAs702kC
- Food and Agriculture Organization of the United Nations. "Mitsukurina owstoni." Fisheries and Aquaculture Department. 2001. (May 14, 2008)http://www.fao.org/fishery/species/13494
- Jordan, Vanessa. "Goblin Shark." Florida Museum of Natural History Ichthyology Department. (May 14, 2008)http://www.flmnh.ufl.edu/FISH/Gallery/Descript/GoblinShark/GoblinShark.html
- Krock, Lexi. "Other Fish in the Sea." NOVA Online. January 2003. (May 14, 2008)http://www.pbs.org/wgbh/nova/fish/other.html
- Mehta, Aalok. "Rare 'Prehistoric' Goblin Shark Caught in Japan." National Geographic. Feb. 9, 2007. (May 14, 2008)http://news.nationalgeographic.com/news/2007/02/070209-goblin-shark.html
- ReefQuest Centre for Shark Research. "Biology of the Goblin Shark." Biology of Sharks and Rays. (May 14, 2008)http://elasmo-research.org/education/shark_profiles/m_owstoni.htm
- Yano, Kazunari; Miya, Masaki; Aizawa, Masahiro; Noichi, Tetsuhisa. "Some aspects of the biology of the goblin shark, Mitsukurina owstoni, collected from the Tokyo Submarine Canyon and adjacent waters, Japan." Ichthyological Research. May 22, 2007. (May 14, 2008)http://www.springerlink.com/content/p430623g30188246/fulltext.pdf