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NOAA Ocean Exploration and Life in the Mariana Trench

Linda Crampton is a writer and experienced science teacher with an honors degree in biology. She enjoys writing about science and nature.

An acorn worm in the Mariana Trench

An acorn worm in the Mariana Trench

A Mysterious Habitat in the Ocean

The Mariana or Marianas Trench is the deepest place in the ocean. It’s a fascinating area. A NOAA expedition has examined the trench and has taken some fantastic photos and videos of its inhabitants. The organization’s exploration of the area lasted for fifty-nine days. This article shares some of the expedition's discoveries and also explores the biology of the mysterious and often beautiful creatures in the trench.

The Mariana Trench is located in the western Pacific Ocean to the east of the Mariana Islands, which are in turn located to the east of the Philippines. The islands include Guam, a U.S. territory. The NOAA expedition's headquarters was the Okeanos Explorer, a converted navy ship. The trench was explored by a remotely operated vehicle, which was controlled by scientists on the ship. Guam serves as the port for the Okeanos Explorer.

All of the NOAA photos in this article were given a public domain license by the organization, though they wanted the name of the organization and the expedition to be mentioned in a particular way. NOAA stands for National Oceanic and Atmospheric Administration. The organization is a government agency in the United States.

Location of Guam and the Mariana Trench

Location of Guam and the Mariana Trench

The Mariana Trench

The Mariana Trench gets its name from the nearby archipelago known as the Mariana Islands. The islands are in turn named after Mariana of Austria (1634–1696), the second wife of King Philip of Spain. Mariana's given name was Maria Anna, but this was changed to the Spanish form when she became Queen. Spanish vessels arrived at the arc-shaped archipelago in the sixteenth century. The indigenous people of the islands are the Chamoru. They are also known as the Chamorro.

The trench was formed by the collision of two of the plates that make up the Earth's crust. The Pacific plate moved—and is still moving—underneath the Philippine plate in a process known as subduction. The downward movement of the plate created the trench. Hot magma and volcanoes that were produced as a result of the movement created the islands.

The collision of two of the Earth's crustal plates that are covered by ocean; the Mariana Trench and Islands were formed by this process.

The collision of two of the Earth's crustal plates that are covered by ocean; the Mariana Trench and Islands were formed by this process.

Mariana Trench Statistics

Researchers at various organizations have made the following measurements. The measurements vary slightly depending on the organization involved. They may be updated as equipment and techniques improve.

  • The trench is approximately 10,944 metres (36,069 feet or 6.831 miles) deep at its deepest point. This area is known as Challenger Deep.
  • Challenger Deep is located 332 km (206 miles) southwest of Guam.
  • The trench is about 2,500 metres (1,500 miles) long.
  • It's also 43 miles wide, on average.
  • At the bottom of the trench, the pressure is more than a thousand times greater than air pressure at sea level.

Although the Mariana Trench is the deepest part the ocean, its bottom is not the closest surface to the centre of the Earth. Because the Earth bulges at the equator, some areas of the Arctic seabed are actually closer to the Earth's centre.

The acorn worm shown in the video below is a strange creature compared to the known species.

Acorn Worms: Phylum Hemichordata

Acorn worms belong to the phylum Hemichordata and the class Enteropneusta. The body of an acorn worm has three sections, as shown in the illustration below. The first section is the proboscis, the middle one is the collar, and the last and longest section is the trunk. The proboscis and collar look somewhat like an acorn (the nut of an oak tree), which gave the worms their name.

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The proboscis is used to burrow through the sediment on the seabed. Some acorn worms take in sediment through their mouth and then digest organic materials and microbes in the sediment. Others filter nutrient particles and microorganisms out of the water via their gills. The gills are also used for respiration. As in a fish, water enters the worm's mouth, flows over its gills, and then travels out of the body through the gill slits. The gills absorb oxygen from the water and send it into the bloodstream. Carbon dioxide moves in the opposite direction.

Basic anatomy of an acorn worm; the animal has no eyes or other specialized sense organs but it does have receptors that can detect light and chemicals.

Basic anatomy of an acorn worm; the animal has no eyes or other specialized sense organs but it does have receptors that can detect light and chemicals.

Deep-Sea Acorn Worms

Unlike acorn worms living in shallow water, the ones discovered in deep water are very long. Their body may be more than eight feet in length. In addition, the worms are seen stretched out over the seabed. The ones at shallow depths build a U-shaped burrow and stay in it with most of their body hidden from view. As at least one researcher has said, the bodies of the deep water animals look too delicate to dig a burrow. Shallow water acorn worms are often dull in colour. The vibrant colour of deep-water forms was a surprise for scientists.

A basket star; according to NOAA, there is more than one creature in this intriguing photograph

A basket star; according to NOAA, there is more than one creature in this intriguing photograph

Basket stars are classified in the class Ophiuroidea. They belong to the phylum Echinodermata, like starfish (also called sea stars), sea urchins, sea cucumbers, and sand dollars.

A top view of a Northern basket star (not from the Mariana Trench) showing the appearance of a single individual

A top view of a Northern basket star (not from the Mariana Trench) showing the appearance of a single individual

Basket Stars: Phylum Echinodermata


Basket stars resemble starfish but have five long, slender, and flexible arms instead of relatively thick and stiff ones. Each arm branches repeatedly, forming narrower branches as it does so. The terminal branches are very fine and are often curled at their tips.

The central disk of a basket star is more distinct than that of a starfish. The design created by the branches around the disk often looks like lace or a mesh. The arms are not always arranged neatly as in the animal above, however. Basket stars sometimes have an untidy and very strange appearance.

Locomotion and Feeding

Basket stars move over their substrate by wriggling their arms. The animals curl into a ball if they are threatened. The arms are used to catch prey as well as move the animal. A basket star positions itself in a water current when it feeds. The spines, hooks, and coils on the arms are very useful for catching small prey like krill, other crustaceans, and zooplankton.

Once the prey is caught, it's gradually moved towards the mouth, which is located on the underside of the central disk. The rows of small tube feet under the arms help in the process of transporting the food. Unlike the case in starfish, the tube feet don't have suction cups and aren't useful in locomotion.

At least some of the starfish in the Mariana Trench are unusual, as the photos below show. The orange animal has soft arms, most of which are folded up. The bumps on the surface are spines. Each spine contains tiny claws called pedicillariae, which protect the animal. Pedicillariae are found in other starfish as well.

A starfish belonging to the genus Coronaster

A starfish belonging to the genus Coronaster

Novodinia, a brisingid sea star, on top of dead bamboo coral

Novodinia, a brisingid sea star, on top of dead bamboo coral

Brisingid sea stars are found in deep water. Unlike typical starfish that move over a substrate to find food, brisingids extend their arms upwards to trap tiny prey creatures being carried by water currents. This process is known as suspension feeding.

Facts About Jellyfish: Phylum Cnidaria

Like starfish, jellyfish are creatures that don't deserve the word fish in their name. Some researchers and organizations use the word "jellies" to refer to the animals, but the word jellyfish is still very popular.

Jellyfish are actually one stage in the life cycle of the organism. The other stage is the polyp stage, which gives rise to the jellyfish stage. A jellyfish consists of a gelatinous bell that contains the internal organs and contracts or pulsates in order to move the animal. Tentacles dangle from the bell and surround the mouth. The tentacles contain stinging cells that kill prey animals.

The stinging cells of a jellyfish are known as cnidocytes. (The initial c in the words Cnidaria and cnidocytes is silent.) A cnidocyte contains a capsule called a nematocyst. The capsule contains a harpoon-like structure that shoots venom into the prey. In some species of jellyfish, the "harpoon" can penetrate human skin and the venom is strong enough to hurt a person.

Deep-Sea Anglerfish: Class Osteichthyes

Anglerfish catch their prey with a fishing technique, as their name suggests. They actually have the equivalent of a fishing rod attached to their head. When a prey animal is nearby, the anglerfish lowers its rod, which has a lure at the tip. The lure is technically known as an esca. When a curious animal approaches the esca, the anglerfish swallows the animal.

A famous species of deep-sea anglerfish is Melanocetus johnsoni. Its common name is the humpback anglerfish or the black sea devil. It has a fearsome expression, sharp teeth, and a long fishing rod with a bioluminescent lure. When it swims through dark water, its glowing lure is very noticeable. The fish photographed in the Mariana Trench looks very different, however, and has a shorter fishing rod.

The genus and species of the fish below wasn't identified on the NOAA website, but I found a YouTube video of a deep-sea anglerfish with a similar appearance. This fish has been seen in deep water off the coast of California and is shown in the video below. Scientists believe that the fish is blue when it's young and then turns rose and finally red as it matures. It has the scientific name of Chaunacops coloratus.

A deep-sea anglerfish; the white spot between its eyes is the lure of its fishing rod

A deep-sea anglerfish; the white spot between its eyes is the lure of its fishing rod

The video below shows a deep sea-anglerfish in California. The animal is very similar in appearance to the one in the photo above.

Effects of Human Activity on the Mariana Trench

In addition to interesting information, the NOAA Ocean Explorer website contains two sad images of trash in the Mariana Trench—an empty beer can at 3,780 metres depth and an empty food can at 4,947 metres depth. The website says that other items of trash were found in the 2016 exploration of the trench, including several plastic bags, a piece of rope, and an item of clothing. Even the deepest part of the ocean is not immune to the action of humans.

The Mariana Trench is not a silent place. In 2016, a team consisting of members of NOAA, Oregon State University, and the U.S. Coast Guard placed a protected hydrophone in the Challenger Deep trough. The hydrophone recorded the sounds that were present in the trough over a period of three weeks.

Many of the sounds in the trench were caused by near and distant earthquakes. The "moans" of distant baleen whales were also heard, as well as noise created by a category 4 typhoon overhead. In addition to these natural sounds, however, there was a lot of noise created by the propellers of ships. Scientists hope to repeat their recordings over time so that they can monitor the noise that humans are adding to the trench environment.

There was also a lot of noise from ship traffic, identifiable by the clear sound pattern the ship propellers make when they pass by. Guam is very close to Challenger Deep and is a regional hub for container shipping with China and The Philippines.

— Robert Dziak, NOAA scientist

Mariana Trench Mysteries

Despite the high pressure and the darkness in the Mariana Trench, many different invertebrates and fish have been found there. The 2016 exploration revealed animals that have never been seen before or which have never been seen alive. It also showed us strange and unusual forms of animals that we see in other parts of the ocean.

Every time researchers explore the trench, new discoveries are made. It's a very interesting place that may still hold surprises for us. Other people have visited the trench and Challenger Deep since 2016, but the explorations that appeal to me are the detailed ones that look at life in the trench, like the NOAA one. Hopefully, another expedition in the future will reveal some additional facts about the organisms in the area. I‘m looking forward to seeing more reports about the Mariana Trench.


© 2016 Linda Crampton


Linda Crampton (author) from British Columbia, Canada on July 01, 2020:

Thank you for the comment.

idi on July 01, 2020:

useful info

Linda Crampton (author) from British Columbia, Canada on August 15, 2019:

I know what you mean, but I think the acorn worm is more cute than blobby. It's an interesting creature.

south wind on August 15, 2019:

yuk that thing is soo blobby and cuteish

Linda Crampton (author) from British Columbia, Canada on April 17, 2017:

Thank you, Scribenet. I think that the creatures that live in deep water are fascinating, too. There is so much that we need to learn about them.

Maggie Griess from Ontario, Canada on April 17, 2017:

Wonderful hub. Deep sea creatures are so beautiful and fascinating. The oceans truly are a "new frontier" that should have plenty of exploration. Sad that trash has found its way into such depths.

Linda Crampton (author) from British Columbia, Canada on September 18, 2016:

Thank you for the comment, vespawoolf. The trench is certainly interesting. I'm looking forward to hearing more news about life there.

Vespa Woolf from Peru, South America on September 18, 2016:

What an interesting article! I'd never heard of this trench and all the fascinating sealife that can be found there. Thank you for sharing.

Linda Crampton (author) from British Columbia, Canada on August 01, 2016:

Hi, Dianna. I agree - the acorn worm looks both crazy and beautiful! The animals in the trench are fascinating.

teaches12345 on August 01, 2016:

The acorn worm is crazy looking but till beautiful. I enjoyed learning about the Mariana Trench. It certainly hosts some interesting creatures.

Linda Crampton (author) from British Columbia, Canada on July 31, 2016:

Thanks for the comment, Maren Morgan. The noise pollution in the trench is worrying. I hope it doesn't get any worse.

Maren Elizabeth Morgan from Pennsylvania on July 31, 2016:

Thanks for the fabulous photos and videos. Dad to learn about human noise pollution.

Linda Crampton (author) from British Columbia, Canada on July 29, 2016:

Thank you so much, Nell. I agree - the creatures at the bottom of the ocean are wonderful and very interesting to observe.

Nell Rose on July 28, 2016:

It never fails to amaze me the wonderful and spectacular creatures at the bottom of the ocean. That's what I love about your hubs alicia, so detailed and fascinating to read, nell

Linda Crampton (author) from British Columbia, Canada on July 24, 2016:

Hi, Bill. Yes, it's very sad that trash has reached the trench. We aren't treating our world very well. Thank you for the visit and comment.

Bill De Giulio from Massachusetts on July 24, 2016:

Fascinating stuff Linda. It's an amazing world we live in, thank you for bringing it to us and explaining it all in a way that we can understand. It's sad that even in the most remote places on earth there is trash left by mankind.

Linda Crampton (author) from British Columbia, Canada on July 23, 2016:

Thank you, Faith! I appreciate your kindness very much. Blessings to you as well.

Faith Reaper from southern USA on July 23, 2016:

Fascinating article, Linda!

It's so wonderful to know there are new discoveries being made of life in the deep seas. Such interesting creatures there in the Mariana Trench.

The photos and videos are beautiful and spectacular. I always learn so much from reading your interesting hubs.


Linda Crampton (author) from British Columbia, Canada on July 22, 2016:

Thank you very much for the kind comment, ChitrangadaSharan. I agree - ocean trenches are fabulous places! The life there is often strange and amazing.

Chitrangada Sharan from New Delhi, India on July 22, 2016:

What an excellent hub with so much interesting information about life in the Mariana Trench!

I enjoy seeing documentaries about this. Your pictures and videos are amazing. Ocean trenches are fabulous places and the organisms living there look so interesting in form, quite different from what we regularly see.

Thanks for this educative and well presented hub!

Linda Crampton (author) from British Columbia, Canada on July 20, 2016:

Hi, Mel. It is fascinating to see how life can survive in such a seemingly inhospitable place as the trench. A lot of the animals there could certainly be considered bizarre! Thanks for the comment.

Mel Carriere from Snowbound and down in Northern Colorado on July 20, 2016:

What a creepy, bizarre, other-worldly place. The naysayers who think we will never find life outside Earth need only to look at the Marianas trench to see that life is tenacious, and can endure in the most extreme environments. Great article!

Linda Crampton (author) from British Columbia, Canada on July 19, 2016:

Thank you very much, Larry. Ocean trenches are fascinating places. Like you, I've been interested in the trenches and their organisms for a long time.

Larry Rankin from Oklahoma on July 19, 2016:

The Mariana Trench has always fascinated me. Some of the most extreme organisms in the world.

Wonderful read and beautiful visual accompaniments.

Linda Crampton (author) from British Columbia, Canada on July 18, 2016:

Thanks so much, Jodah. The Mariana Trench is definitely intriguing! I'm glad that photos and videos of the area are available and that researchers are sharing their experiences.

Linda Crampton (author) from British Columbia, Canada on July 18, 2016:

Hi, Rachel. Thank you for the lovely comment. I'm very interested in the ocean and marine biology, too. This article was very enjoyable to create! Blessings to you as well.

John Hansen from Gondwana Land on July 18, 2016:

A wonderful article, AliciaC. I have always been intrigued by the Mariana Trench and the amazing creatures in its depths. The videos are brilliant also. Thank you for sharing.

Rachel L Alba on July 18, 2016:

Hi Alicia, This hub is so, so, so, interesting. I love to see and read anything about the ocean and the ocean floor. I love the videos also, especially the basket star fish. Thank you for the work you put into this.

Blessings to you.

Linda Crampton (author) from British Columbia, Canada on July 18, 2016:

I don't like small spaces either, Bill. I would certainly be willing to explore the trench from the safety of a ship, though. The researchers have a fascinating job.

Bill Holland from Olympia, WA on July 18, 2016:

You couldn't pay me enough to go down there. Seriously! That confinement in a small space would drive this boy nutso! LOL Still enjoyed this article, though. It's all fascinating. I just don't want to be a part of the discover process.

Linda Crampton (author) from British Columbia, Canada on July 17, 2016:

Thank you very much for the comment and the share, Jackie! I appreciate your support. I definitely agree about the fantastic fine for littering. We need to find a solution for the ocean pollution problem.

Jackie Lynnley from the beautiful south on July 17, 2016:

Wow, how interesting! This was so very fantastic to read and observe. Terrible about the trash though, they should really make a "fantastic" fine for anyone caught littering the waters anywhere to make someone think twice before they do.

Just loved this and sharing!

Linda Crampton (author) from British Columbia, Canada on July 17, 2016:

Hi, Flourish. They are unusual creatures. The exploration was done via a remotely controlled vehicle with a camera. I don't know whether it was capable of retrieving trash. It's very sad that garbage is appearing in the trench.

FlourishAnyway from USA on July 17, 2016:

Very unusual creatures I've neither heard of nor seen. That basket star looked like a mass of tree branches (except the strange middle). It's sad that even at those depths there was trash. I wonder it they just left it there or attempted to retrieve it?

Linda Crampton (author) from British Columbia, Canada on July 17, 2016:

Thank you very much for the kind comment, Buildreps. It is incredible that life can flourish in such deep water. The trench is a wonderful place to explore.

Buildreps from Europe on July 17, 2016:

I love this kind of research to the deep oceans. It's so incredible that life can flourish so seemingly effortless at this enormous pressure. Fabulous article on this intriguing deep trenches. Thanks for the great article.

Linda Crampton (author) from British Columbia, Canada on July 17, 2016:

Hi, Heidi. Thanks for the comment. I agree - some of the life forms in the trench do look other worldly! It's certainly a wondrous place.

Heidi Thorne from Chicago Area on July 17, 2016:

I have seen documentaries on this truly incredible part of our planet. The creatures and flora truly look other-worldly. Might give us a glimpse of life we might find on other planets someday. Thanks for sharing some insight and info on this wondrous place!

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