6 Fascinating Animals From Every Layer Of The Ocean

This World Oceans Day, we thought we’d take a journey through the different layers of the ocean and the animals that live there. The ocean covers about 70% of Earth’s surface, and 94% of wildlife lives here, producing over half the planet’s oxygen. Oceans feed us, support wildlife, help our economy, and more, yet they are under threat. 8 million tonnes of plastic enter the ocean every year and overfishing endangers countless numbers of animals like sharks.

Sunlight Zone – Sea Turtles

The sunlight zone, or the photic zone, is the top layer of the ocean. It is home to the majority of aquatic wildlife. Sunlight penetrates this level up to around 200m, and the warmth allows phytoplankton to photosynthesise.

The sunlight zone is also home to animals like the sea turtle. There are seven different species of sea turtles, and they have been around for around 100 million years. They spend the majority of their lives in the water and are actually a migratory species. The entire ocean ecosystem is supported by sea turtles, who help maintain coral reefs and other aquatic biomes. 

Twilight Zone – Jellyfish

We’re about 200m below the surface now. We find lots of funky marine life here and, in particular, we find a lot of jellyfish. These crazy looking creatures have no brain, no heart, no bones and no blood - they’re 98% water! When they become stressed, their cells undergo a very special process, where they become brand new again! These jellies could prove very important to scientific and medical research, particularly in the fight against aggressive diseases like cancer.

Jellyfish have been around for a really long time; although fossils of these guys are hard to come by, evidence suggests the earliest jellies could have been floating around about 600 million years ago!

Midnight Zone – Frilled shark

We’re about 1000m below the surface here. As the name suggests, the midnight zone is also very dark. It’s so dark, we don’t get much, if any, plant life. So, all the animals found here are either predators or scavengers. Some really cool sharks live in this zone, like the frilled shark.

Frilled sharks get their name from their frilly gills, which are placed far back on their bodies. They swim similarly to an eel or snake, but they have been known to lunge at prey and swallow them whole. These sharks give birth to live young, and once born, the young sharks can survive completely on their own.

The Abyss – Dumbo Octopus

The abyss is 3000-6000m below the surface of the ocean. It is the largest environment for life on Earth. Lots of large animals like sharks can be found in the abyss, but so can smaller animals like tiny fish and shrimp. As this zone is so deep and vast, the sunlight cannot penetrate it, and it’s very dark. Because of this darkness, a lot of animals utilise a very special adaptation; bioluminescence! These unique animals have phosphorescent cells, and this is why certain animals appear to glow bright (often blue) colours in the dark waters.

Other interesting animals live in the abyssal layer, like the Dumbo Octopus! These octopi are the deepest living genus of their species, living at around 13,000 feet below sea level. They use their big, ear-like fins to propel themselves through the water. Due to the scarcity of life at this level, they always have eggs at different stages of development in their bodies and store sperm for long periods after mating to maximise the chances of reproduction.

Trenches - Barrel Amphipod

The surface of the ocean is far from smooth. With lots of curves, edges, cliffs and holes,  got lots cliffs and holes – and even mountains and volcanos – this layer marks the ocean’s trenches. The Mauna Kea Volcano in Hawaii, for example, begins on the ocean floor, extending 6000m below the surface. The ocean floor also has many deep trenches – The Mariana Trench is the deepest location on Earth; in fact, it’s over 36,000 ft deep! Life here can be tough. The pressure is 1000x greater than on the surface, there’s no sunlight, and it’s freezing cold.

Most animals avoid this hostile habitat, but there are some, like the Barrel Amphipod, which have interesting survival techniques. These deep-sea crustaceans cling onto salps with their sharp claws, ripping apart the soft tissue. After the salp has died, the amphipod shelters inside the carcass, reshaping it into a barrel and toughening the structure with chemicals secreted from its body.

Ocean Floor – Sea cucumber

We’ve finally reached the bottom! The structure of the sea floor is often dictated by tectonic plates, which move and shift over time. Most sea beds are covered in layers of marine sediments, made up of varying combinations of land sediment, biological organisms, sediment from chemical reactions, and cosmic sediment.

The variety of animals that live on the sea floor is called ‘Benthos’ and includes animals like sea cucumbers. They are in the same class are sea urchins and starfish, and there are over 1,000 species of sea cucumber.  They feed on tiny waste particles floating in the water and have up to 30 tentacles to catch their food.

Want to learn more about the ocean? Contact us today for more info on our Oceans workshop!