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8. The Goblin Shark: A Living Fossil from the Depths
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Often referred to as a "living fossil" because of its prehistoric look and ancient heritage, the goblin shark (Mitsukurina owstoni) is among the most strange and mysterious species of deep sea life. Belonging to the family Mitsukurinidae, this uncommon species is the only surviving example of a lineage going back over 125 million years. The unusual shape and specialised hunting strategies of the goblin shark have attracted great public interest as well as strong scientific attention.
The extended, flattened snout of the goblin shark—often referred to as a rostrum—is particularly arresting. The shark gets its unique "goblin-like" look from this unusual protrusion, which spans much beyond the mouth. Specialised sensory organs known as the ampullae of Lorenzini abound on the rostrum, enabling the shark to detect the weak electrical fields generated by possible prey in the dark of the deep ocean. The survival of the goblin shark in an environment where visual clues are few or absent depends on this highly evolved electrosense.
The extraordinarily protrusible jaws of the goblin shark are maybe its most amazing adaption. The shark can quickly extend its jaws far beyond the edge of its snout to create a strong suction that drags prey into its mouth. Among sharks, this jaw mechanism is unusual and made feasible by a sophisticated system of ligaments and cartilage allowing the whole jaw apparatus to move forward. With the whole process of extending the jaws, catching prey, and withdrawing, this jaw protrusion moves shockingly quickly—less than a second.
Usually living between 270 and 960 meters, the goblin shark's body is suited for survival in the deep sea; yet it has been found as deep as 1,300 meters. Its soft, flabby body has a pinkish-gray hue that, given the filtering of light at extreme depths, most likely seems red in its natural home. In the darkly lit seas where the shark resides, this colouration can provide cover. Small and vestigial-looking, the shark's eyes provide more proof of its reliance on other senses in the dark depths.
Though it looks intimidating, the goblin shark is a rather slow predator that depends more on ambush techniques than aggressive hunt of prey. Its main food is crustaceans, cephalopods, and teleost fishes. The fact that the shark may find and seize prey in total darkness is evidence of how well its sensory and eating adaptations work.
Because of their rareness and the difficulties of researching deep-sea creatures, reproduction in goblin sharks is poorly known. Like many deep-sea sharks, they are thought to be ovoviviparous—that is, the eggs hatch inside the female's body and she delivers live offspring. Still unresolved, though, are the specifics of their reproductive cycle, gestation length, and number of children.
Scientists find it difficult to investigate the rare goblin shark because of its deep-sea habitat. Most of what we know about these species comes from the odd stranding or from specimens caught inadvertently in deep-sea fishing nets. Every fresh specimen offers important information that enables scientists to put the life history and ecology of this mysterious animal together.
The rarity of the goblin shark and deep-sea habitat hinder efforts for conservation. Although commercial fisheries not target it, deep-sea trawl operations can catch it as bycatch. Unknown is the effect of such incidental captures on goblin shark populations, which emphasises the necessity of more study and maybe preventive actions for deep-water environments.
The goblin shark reminds us powerfully of the amazing variety and adaptations of life in Earth's least explored frontier as we explore the deep sea. Its special characteristics not only offer understanding of shark evolution but also motivate biomechanical research, especially on highly dynamic jaw systems. Understanding and safeguarding the biodiversity of the waters on Earth depends on constant research on the goblin shark and other deep-sea species.
