Deep Sea Bloggerhead: Creatures of the Deep

Wednesday, February 24, 2010

Creatures of the Deep

For years people thought that life could not exist in places without light, at just above freezing temperatures and at crushing pressures so powerful that some minerals simply dissolve. But we were wrong. Scientists have recently found that life can exist at depths of 11 km under the ocean’s surface, the Challenger Deep, with the discovery of single celled foraminifera; these microscopic creatures use debris that falls from above to build their homes. Technically deep-sea creatures occupy a zone 1800 m below the surface, but in this blog I will be covering a wide variety of creatures that live in or below the photic zone, a depth where the light is insufficient for photosynthesis to occur. Such fish as Fangtooth, anoplogaster cornuta, or the deep-sea Angler, Melanocetus johnsonii, both of which occupy the midwater range, 700-1000 m.

Because there is no light where these fish live, they have to rely on methods other than sight to catch their prey. Many fish have evolved their eyes making them larger so as to catch the bioluminescent light that fish like the anglers give off: this adaptation is used by both prey, as a way to communicate during mating season, and predators as a way of attracting potential food. The angler literally fishes for his food: he uses a glowing appendage called a photophore to attract his prey, waving it back and forth as a lure.

It is not uncommon for fish living below the photic zone to prey on fishthat are bigger than itself: gulper eels have evolved to have detachable jaws so they can swallow prey 3x bigger than themselves. Other fish have oversized teeth so they can rip and tear at preys much larger than themselves. One example of this is the Fangtooth fish, which has a jaw filled with teeth capable of taking down large prey. The Fangtooth has some of the nastiest teeth in the entire ocean: according to BBC’s Blue Planet the Fangtooth has the largest teeth in the entire ocean proportional to its body. The Fangtooth fish is part of a group of deep-sea fish that are diel migration fish: they spend the day in the deepest parts of the ocean, but at night they migrate to shallower waters to feed.

Recently there have been thousands of discovered creatures that live below the photic zone, but scientists say that there is even more to come. Some marine biologists hypothesize that there are millions of unidentified species living in the deepest parts of the ocean.