![]() ![]() Subsequent cruises have conducted research in the Northeast Pacific and off the coast of the Bahamas. The mission began by deploying autonomous underwater vehicles and sensors in the Atlantic Ocean, offshore from the recently created Northeast US Shelf Long-Term Ecological Research (LTER) site. WHOI's scientists, engineers and technicians are doing this by continuing their groundbreaking work developing new generations of smart robots and other tools necessary to explore the zone. With this mission, WHOI aims to form a new body of knowledge that will promote responsible stewardship of the ocean and shed new light on how our planet works. WHOI’s mission comes at a crucial time to advance human understanding of this vast frontier. Commercial fishing interests are scaling up efforts to harvest the twilight zone, despite our lack of knowledge about the region and its inhabitants. The goal is to understand how the extraction of resources from this zone might affect it in ways that could reverberate throughout the ocean and around the world, for centuries to come. Woods Hole Oceanographic Institution (WHOI) is launching a mission to explore the twilight zone, a globe-spanning ecosystem that is deeply intertwined with the entire marine food web and even Earth’s climate system. Yet, the region has been largely unexplored. The world’s largest animal migration takes place here every day. In fact, the twilight zone is believed to be home to more than one million new species, and up to 90 percent of the world’s total fish biomass. The sun in the twilight zone is barely a glimmer, but the region is teeming with life. The photophores give off a greenish light.The ocean’s twilight zone, known to scientists as the mesopelagic or midwater region, sits beyond human sight, about 200 to 1,000 meters beneath the surface. They make light with special organs in their bodies called photophores. Some animals that live in this zone make their own light with bioluminescence. They either stalk it or wait for it to float or swim by. Most of the fish in this zone don't chase their food. Other fish have large eyes that help them see in the dark waters. Some fish, like viper fish and the hatchet fish, have sharp fangs and large mouths that help them catch food. When a predator is looking up at them, they are so thin that they are hard to see! Other organisms in this zone are red or black in color to better blend in with the dark water. Many animals in this zone have thin bodies that help them hide from predators. Octopus, squid, and the hatchet fish are some of the animals that can be found in this zone. There are no plants in this zone, because there is not enough light for photosynthesis. The Twilight Zone Animals that live in the twilight zone must be able to survive cold temperatures, an increase in water pressure and dark waters. When a predator is looking at them from below, they blend into the lighter waters above. When a predator is looking down on them from above, they blend into the darker waters below. These animals are dark on the top and lighter on their undersides. There are not a lot of places to hide in the sunlit zone! Some species have an adaptation called countershading. Lots of marine animals can be found in the sunlit zone including sharks, tuna, mackerel, jellyfish, sea turtles, seals and sea lions and stingrays. Let the Sun Shine In The sunlit zone is home to a wide variety of marine species because plants can grow there and water temperatures are relatively warm. Sometimes people divide the midnight zone into two zones: the aphotic zone and the abyss. No sunlight reaches this zone and it can reach depths of close to 20,000 feet. The last zone is the aphotic or midnight zone. The dysphotic zone goes down to about 3,300 feet. Some sunlight reaches this zone, but not enough for photosynthesis to occur. The next zone is the dysphotic or twilight zone. The sunlit zone goes down to about 660 feet. Because this zone gets sunlight, photosynthesis can occur and plants can grow here. This is the ocean zone that sunlight penetrates. The top zone is the euphotic or sunlit zone. The ocean can be divided into two basic areas: the benthic zone or ocean floor and the pelagic zone or ocean waters.įrom Sunlight to Darkness The pelagic region is divided into three zones. It is the water away from the coastal waters and contains a wide variety of life. The open ocean makes up about 65 percent of ocean water. If you look beneath the surface of the open ocean, you'll find a diverse and unique environment. ![]()
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