They then return to the safer, darker depths at sunrise. In this mass marine commute, fishes, squid and zooplankton alike travel to feed in plankton-rich waters at night when there’s a reduced risk of large predators. Multiple species make trips in search of food every day, spending daylight hours up to 1000m deep and rising up as far as 800m closer to the surface at sunset. It’s bewildering perhaps that while the ocean represents an extreme environment for us, many of its inhabitants regularly travel vertical distances that would take our breath away. Diel vertical migration is the term, and loads of other animals do it too.” “There are many deep-sea squids that move hundreds of meters shallower then deeper over the course of the day, but that would be considered movement or migration, not diving. “When I think of deep diving I think of marine mammals like elephant seals, beaked whales, sperm whales… I don’t think of cephalopods as divers much at all,” she says. Yet when asked about deep sea divers, she still thinks of mammals first. Stephanie Bush, a research associate at the Monterey Bay Aquarium Research Institute, has a particular interest in cephalopods of the deep sea. These elusive whales aren’t competing for glory, but hunting for deep sea squid. In the lead are Cuvier’s beaked whales ( Ziphius cavirostris) that can dive from the ocean’s surface down to 2,992m (9,816ft) thanks to adaptations that help them conserve oxygen and survive extreme pressure. When it comes to mammalian free-divers, the cetaceans beat even the best of us fins down. As pressure builds on the descent, nitrogen dissolves into the tissues of the body so if an ascent is made too quickly the gas forms bubbles affecting everything from the joints and skin, to the heart and brain. The ascent is always the riskiest part of a scuba dive due to the possibility of decompression sickness (DCS) if a diver cannot balance the gases in their body. While it took him 12 minutes to descend, he spent almost 15 hours returning to the surface. The special forces officer and diving enthusiast plunged 332.35m (1,090 ft 4.5 in). In 2015, Ahmed Gabr achieved a record-breaking scuba dive in the Red Sea at Dahab, Egypt. It’s a balancing act scuba divers are all familiar with. According to a study published in 2014, this is a biochemical limit, beyond which fish lack the ability to balance out the destabilising effects of pressure on their bodies. Based on the few specimens that have been caught, scientists predict it is unlikely any snailfish will be found living deeper than 8,200m below the surface. The deep-dwelling fish have a limited range, with different species discovered in different trenches, and they are described as ‘benthic’ meaning they have a close relationship with the seabed. Snailfish ( Liparidae) are widely distributed, but poorly understood, particularly the species encountered at such extreme depths. Three years later, Japanese scientists working with the national broadcaster NHK filmed another snailfish 85 feet deeper in the Trench. At 8,145m (26,722 ft) a pale pink snailfish was attracted to their bait and welcomed into the record books. In 2014, researchers from the University of Hawaii, US, and the University of Aberdeen, UK, teamed up to use an innovative lander to record video footage in the Mariana Trench. So, not all species familiar with the depths can be described as divers.ĭuring this intensive period of exploration, there has also been plenty of competition to find the deepest living fish. Yet these creatures have never been seen outside of this pitch-dark environment where they are perfectly adapted to the harsh conditions. The video footage from Cameron’s mission revealed there was indeed life at the very bottom of the ocean in the shape of wood-eating crustaceans, camouflaged sea cucumbers and single-celled lifeforms that catch food in their sticky filaments.
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