5. Plunder Down Under


Plunder Down Under

Dive deep into the ocean abyss, where the sunlight can no longer penetrate this world of eerie, cold darkness. Miles beneath the surface lies and unexplored world, filled with sights we have never imagined!   

 Gif Credit: Tenor

How deep is it?

The deepest region is the Marianas Trench near Guam that is measured at a staggering 11,034 m deep. To compare the Eiffel tower is 324 m tall, the Burj Khalifa (tallest building in the world) is 830 m tall and Mt.Everest is 8, 848 m tall. This depth is called the Hadal zone which is named after Hades – god of the underworld. On March 26th 2012, acclaimed film director and adventurer James Cameron set the world record for journeying to the bottom of this allusive region.

Gif Credit: Giphy

The deep sea begins at about 200 m down under and there several factors that shift when going deep down. For instance the deeper you go, the less sunlight present. AS you venture down deeper and deeper to the bottom you will go through 3 main light zones: the sunlight zone, the twilight zone and the midnight zone.

Gif Credit: Ficazo

The sunlight zone is the top layer of the ocean and his is were about 90% of marine animals live due to the ability of photosynthesis.

The twilight zone is where only a tiny bit of light is able to penetrate the water this far deep. Moreover, the pressure is also increase thus making difficult for plants to thrive. You’d only see those animals specifically adapted to little sunlight dependence. This could be animals like the hatchet fish or viperfish.

The midnight zone is in deep sea territory. It’s complete darkness. This zone accounts for about 90% of the ocean. Marine animals here are typically found living by hydro thermal vents for its mineral-rich nutrients it expels. You’d see animals like angler fish or vampire squids.


Gif Credit: Giphy

Another shift that occurs is the rise of pressure in the deep sea. Every 33 feet down, 15 pounds per square inch increase in pressure. That means if you were down at 2,500 m you would have the equivalent of an elephant standing on your toe. Uncomfortable eh? How this pressure affects the body while diving is fascinating. At just 100 feet down, your lungs would begin to contract, thus giving you little air supply and an instinctively the body response to protect the vital organs who trigger the blood supply to be forced to the heart and brain. It is crazy how the human body responds to this pressure, and makes it difficult for scientists to easily access data from the deep sea. When James Cameron was a the bottom of the ocean, he said to CBS News that he had to trust that the engineers did a good job on his submersible, otherwise if there was a leak his submersible would implode.


With this extreme environment follows some fairly extreme and bizarre adaptations. Keep in mind that the deep sea is a dark, high pressure and freezing environment. Moreover, I’d like to emphasize that there remains little known about this area so insight behind these adaptations are limited.

Gif Credit: Giphy

Body Color:

Similarly to the animals above, body color is used to camouflage themselves and help them either sneak up on prey or hide from predators. Typically, this means that you’d find animals with transparent bodies, black bodies or even red (the black of red light helps to hid them).

Gif Credit: Giphy

Bio luminescence:

This adaptation can be used to lure prey, communicate with others of the same species or even to confuse predators. An adaptation is caused by either bioluminescent bacteria, as is the case for anglerfish or from the photosphores of an animal’s body.  

Gif Credit: Gifer

Large Mouths:

It seems to be a trend for many deep sea fish to have large jaws; this theorized to increase the probability of actually catching food in the dark. The bigger the bite the better the odds for a delicious meal.

Gif Credit: Giphy


This one is still a mystery. There are animals such as the giant isopod and the giant squid that call the deep sea, but why are they so much bigger than those higher up in the ocean? Some think it’s because they have less predators in the deep so they have time to grow larger. Others theorize that it has something to do with the pressure.

Photo Cred: Business Insider


You may have heard of countershading, which orcas and herring use to camouflage, deep sea animals use as well in the opposite way. It’s when an animal produces light to blend into the light of their background. With the just right amount of light produced, an animal can effectively  hide their silhouette.

Gif Credit: KU

Burglar Alarm:

This is an amazing way that some animals get the attacker attacked. Essentially, they spit out bio luminescence when being attacked which in turns causes the predator to be highly visible and appealing to a bigger predator nearby.

Questions for Your Jr. Biologists:

  1. Why is there such limited information about the deep sea?: Due to mainly the pressure it's very difficult to engineer equipment that can repeatedly withstand it. Moreover, it's tricky to get quality video footage or find animals in the darkness. 
  2. How do animals survive in this extreme environment?: Through adaptations like bio luminescence, body color, big mouths, gigantism, counter illumination and burglar alarms. 
  3. Could humans just get a really long snorkel to explore the deep sea?: The human is too fragile to withstand the pressure of the deep sea. The bodily response is slowed heart beat and constricted lung capacity. 
    Do you have any questions for Club Volunteers or our Coordinator, Jordan ? Ask away on our Discussion Board!


-Complete the James Cameron Deep Sea 3D Challenge here 

-Create a deep sea ecosystem here

-Complete these STEM deep sea activities here

Learning Objectives

-Learn about the the differing light zones of the sea. 

-Observe the range of adaptations for deep sea animals.

-Understand the effects that the pressure, light and temperature has upon a human. 

-Acknowledge that the deep sea is a highly mysterious area of research and understant why. 

Continue to 6. Operation Orca »