Editor’s note: On March 26, 2012, James Cameron made a record-breaking solo dive to the Earth’s deepest point, successfully piloting the DEEPSEA CHALLENGER nearly 7 seven miles (11 kilometers) to the Challenger Deep in the Mariana Trench. DEEPSEA CHALLENGE is now in its second phase—scientific analysis of the expedition’s findings. Click here for news about the historic dive, an exclusive postdive interview with Cameron, and information about the next phase of the expedition.
At the frigid bottoms of Earth’s ocean trenches, scientists have discovered life-forms where they once thought none could survive. From gelatinous animals called holothurians to shrimp-like creatures named amphipods, the animals of the deep can quickly start to resemble alien beings. But they live here, on planet Earth, and scientists hope to discover more new life-forms during the DEEPSEA CHALLENGE expedition.
In addition to adding new animals to the list of known species, studying how these animals survive at depth could lead to new developments in biotechnology and even provide clues about how to search for life on other planets.
While some samples of creatures from the Mariana Trench have been taken, most have been collected by trawling or by sending remotely operated vehicles. The DEEPSEA CHALLENGER is taking a completely different approach. With multiple cameras and the most advanced lighting ever taken to such depths, the sub will allow a human to look around and interpret the surrounding environment directly. In addition, when a sample is taken, sophisticated film equipment can record where it came from, what else was there, and any activity that might have been going on. When taken as a whole, the various samples, data points, and experiences collected on this project will result in baseline data that can be used to monitor future changes in the trench as research continues in life’s most extreme environment.
Below are some of the areas the expedition scientists will be examining.
Scientists are particularly interested in the microorganisms that may be found in the Challenger Deep. Analyzing how deep-sea microbes survive could impact biomedicine and biotechnology. For example, these tiny organisms may be able to resist heavy metals that are toxic to other organisms. They also can feed upon hydrocarbons such as methane or various oils. Some of these creatures have membranes high in omega-3 fatty acids, which prevent the animals from freezing. Studying everything from how their membranes operate to how they replicate their DNA could lead to more discoveries. With careful handling, deep-sea bacteria can be repressurized in special chambers to deep-ocean pressures, isolated, and cultivated in the laboratory, providing a continuing source of biomaterials. The genomes of these bacteria will be unraveled using the latest techniques, revealing their evolutionary relationships with other life.
LIFE ON OTHER PLANETS
Studying life in the extreme environment of the Challenger Deep could also provide insight into how life might survive on other planets. The cold, high-pressure, low-to-no-light conditions of the Mariana Trench are similar in some respects to conditions thought to exist elsewhere in the solar system, such as on some icy moons of Jupiter and Saturn. The temperature and pressure conditions at the Challenger Deep are comparable to what scientists think any life would have to tolerate deep within Europa’s ocean.
Life at the Challenger Deep has evolved special mechanisms for adapting to this environment. For instance, the foraminifera don’t have shells; instead they have tough organic walls. The expedition’s astrobiologist will be analyzing the composition and chemistry of these organisms to better understand how they might help guide our search for life elsewhere.
CREATURES OF THE DEEP
Relatively little is known about the animals that dwell on the deep-ocean floor. Scientists hope to identify new species.
This journey is not just about general discovery. Below are some of the creatures that have already been found in the deep ocean and could be studied further during the DEEPSEA CHALLENGE.
Giant Single-celled Xenophyophores: Recent footage from National Geographic Dropcams deployed in the Mariana Trench revealed these incredible creatures, which can reach 4 inches (10 centimeters) in length and which each have many nuclei but just one enormous cell. They can take various forms, from disclike to wildly undulating, and they consume food by surrounding and absorbing it, similar to more familiar microscopic single-celled creatures such as amoebas.
Fish: Snailfish (Pseudoliparis amblystomopsis) currently hold the record as the deepest living fish ever photographed, having been filmed 4.8 miles (7.7 kilometers) beneath the surface of the Pacific Ocean in 2008. But Jacques Piccard and Don Walsh of the Trieste bathyscaphe mission reported seeing a flatfish when on the bottom of the trench in the 1960s. Since they had no underwater cameras and didn’t collect the fish as a sample, many have dismissed the sighting as a trick of the eye. Walsh says he’s certain that what they saw was a fish. The DEEPSEA CHALLENGE expedition could potentially confirm the Trieste pilots’ story half a century after their sighting.
Crustaceans: Amphipods are some of the most commonly encountered deep-sea creatures living on and above the seafloor. Related to shrimp, these armadillo-like crustaceans will devour almost anything they can find, from bacteria, phytoplankton, and fish to the remains of large animals that have come to rest on the ocean bottom—and they’ve even been known to prey on each other.
Echinoderms: Sea cucumbers (holothurians) are relatives of starfish and are found at all depths in the ocean. They amble across the deep seafloor, vacuuming up mud and digesting the minute organic particles found within. This strategy serves the sea cucumber well—in places they can make up 90 percent of the biomass in the deep sea, making them one of the dominant forms of life on Earth. Strange shapes, patterns, and forms of motion continue to surprise and intrigue scientists with each discovery.
Mollusks: Water pressure at the bottom of the Mariana Trench makes growing a shell a challenge. At great depths calcium carbonate, the material that makes seashells hard and strong, is slowly corroded by seawater. But this hasn’t stopped snails and bivalves from colonizing the trenches. Snails with soft shells have been discovered in the Japan Trench, and dense communities of clams inhabit trench sites where methane-rich fluids percolate through geological faults in the seafloor.
Cnidarians (Sea Anemones, Coral, and Jellyfish): Cnidarians could be encountered on the DEEPSEA CHALLENGER’s journey to the depths, on or above the trench floor and on the steep, rocky walls of the trench. Jellyfish and their relatives have been photographed drifting at great depths, but none have ever been collected, and it’s unknown if they belong to a species new to science. Rocky outcrops deep in the trench may also harbor undiscovered corals, anemones, and other organisms that need a hard surface to grow upon.
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