The ocean has long been a source of intrigue and curiosity for humanity. People have adventured in sailboats, or dove deep to better understand the mysterious blue world. Oceans cover about 70% of the Earth’s surface- that’s quite a bit! Approximately 80% of this vast area has yet to be explored, especially the deeper areas. The deepest point of the ocean is known as Challenger Deep, part of the Mariana Trench, which is near Guam in the Pacific Ocean. Challenger Deep plunges 35,814 feet below sea level. What kinds of things do you think you might find there?

The conditions of the deep ocean (starting at around 656 feet) are tough, to say the least. The waters are very dark and typically cold, as sunlight doesn’t reach so far down into the water. Pressure is high due to the water pressing downwards. As if that weren’t enough, it can be really hard to find food! Side note- it does get warmer near hydrothermal vents, which are hot springs from underwater volcanoes in the bottom of the ocean. Seawater trickles down the vents, gets heated with magma and is released- the water can reach above 700 degrees F. Surrounding areas may be much more pleasant with temperatures around 70 F, as the heated water mixes with the cooler seawater.

Now, you may be thinking: how can anything live down there? Let’s take a step back and consider natural selection. These rough conditions exert a strong selective pressure, leading to natural selection of certain traits in animals. The outcome of the selection is a variety of animals with unusual features that help them thrive in this environment. Many deep-water animals are bioluminescent- they make their own light. This helps them find partners and food, while scaring away predators. Some have very good eyesight, and others are blind. Scientists think that the cell membranes and proteins of deep-water animals have a certain structure and contain molecules to help withstand the cold and pressure.

These creatures are mostly small in size or slow-growing, so they require less food. Animals that need more food will eat plenty of food at once when they find it, or store it between meals.

Critters living near hydrothermal vents have an interesting diet. Bacteria that live near the vents create energy from hydrogen sulfide pouring out of the vents. This process is called chemosynthesis- using chemicals to create energy and grow. Since bacteria have a food source to keep growing, they can sustain other animals. The bacteria are the bottom of the food chain: small animals eat the bacteria, and larger animals eat the smaller animals.

Deep ocean-dwelling animals look different from those found anywhere else. Some hardy inhabitants include anglerfish, arrow tooth eels, vampire squid, tube worms and giant isopods, along with various microbes. If you’re interested, plenty of their photographs are available online!

Scientists are fascinated by the deep waters. Plenty of research and exploration has been done and is in progress. People have travelled in submersible vehicles, sent robots to collect information, and established underwater observatories. Studying the deep waters is important for many reasons. For example, it could help with making discoveries in medicine and energy, and understanding climate change and natural disasters. Would you like to join in the effort?