The common assumption is that all living animals need oxygen to survive. Even fish and worms have certain features, such as gills and pores on the skin, that allow them to extract oxygen from their respective environments. However, there is a small group of animals that defy this particular biological rule. As part of the many wonders of Mother Nature, here is a list of animals that can survive without oxygen.
1. Loricifera
A couple of years ago, scientists discovered the first-ever multicellular animal living in the Mediterranean Ocean that can survive without oxygen. The Loricifera developed this trait because of its habitat.
It resides in the dense salt basin in the Mediterranean Ocean, which lacks oxygenated water. Despite the lack of oxygen, this animal not only survives but also reproduces under the salt brine.
Scientists believe that these creatures spend their entire lifetime under the salt brine. Upon further examination, it was revealed that Loricifera does not have mitochondria. They instead have hydrogenosomes, which perform a similar function as mitochondria only in oxygen-free environments.
2. Bursaphelenchus xylophilus (A Nematode Species)
There is a plant-parasitic nematode known as Bursaphelenchus Xylophilus that can survive for up to 14 days without oxygen. This is achieved through a reversible metabolic process called cryptobiosis, where all processes within a nematode’s body shut down for extended periods. This includes their ability to absorb oxygen from the environment. Unlike Loricifera, this nematode species may die if it doesn’t get access to oxygen.
3. Tubeworms
Tubeworms, especially those that reside near hydrothermal vents, can thrive without oxygen and photosynthesis. These animals survive in two main ways. First, they absorb the hydrogen sulfide from the hydrothermal vents and convert it into energy. Alternatively, they can create a symbiotic relationship with the bacteria that grows inside its tissues.
4. Naked Mole Rats
Besides their distinctive appearance, Naked Mole Rats can survive without oxygen. Unlike other mammals, Naked Mole rats, indigenous in East Africa, can thrive in low-oxygen environments such as caves. In these instances, the rodents switch their metabolism from oxygen to relying on fructose. This allows them to go for considerable periods without oxygen.
5. Brine Shrimp
Brine Shrimp operate similarly to Loricifera. This is expected because they both live under the same conditions. As mentioned, brine waters often feature extreme environmental conditions with low oxygen levels. As a result, Brine Shrimp have evolved and can slow down their metabolism to adapt to low oxygen levels. While in this state, these animals can survive without oxygen.
6. Palaemonetes
Brine Shrimp aren’t the only species that can thrive without oxygen. Another freshwater shrimp species, Palaemonetes, has a similar characteristic. Over the years, these creatures have evolved to have gills that can absorb oxygen, even in low-oxygen environments such as stagnant water. Even though they are not as good as Brine Shrimp when it comes to surviving without oxygen, they can do way better than most animals.
7. Spinoloricus
Spinoloricus was discovered at the same time as Loricifera. They, too, live in oxygen-free waters and thrive well. Also known as the Deep Sea Wonder, Spinoloricus has hydrogenosomes cells that allow them to survive without relying on oxygen.
8. Henneguya Salminicola
Unlike other types of fish, the Henneguya Salminicola is a unique species with quite interesting characteristics. To begin with, it is a parasite that primarily preys on salmon. Also, unlike other fish, it doesn’t have mitochondria. This is a key indicator that this species has long given up its reliance on oxygen.
Being a parasite, this fish thrives by depending solely on its hosts for nutrients, converting it to energy. Without a host and a means of absorbing oxygen, most Henneguya Salminicolas end up dead.
9. Green Sea Turtles
Green Sea Turtles can’t go for days or weeks without oxygen, as with most animals on this list. Additionally, they can hold their breath underwater for up to five hours, which is remarkable. Green Sea Turtles can dive into deep waters and survive for several hours without oxygen when looking for food or avoiding predators. They achieve this by slowing down their metabolism. This mechanism also makes them adept to low-oxygen waters.
10. Mung Bean Weevils
If you put most insects in oxygen-free environments like sealed containers, most won’t make it. However, the Mung Bean Weevil, native to Asia, can survive in low-oxygen environments for extended periods.
To achieve this, these creatures enter a state of anaerobic respiration. The Mung Bean Weevils’ survival ability in such areas has made them a stubborn pest for Asian agricultural enterprises.
11. Sea Cucumbers
On the surface, sea cucumbers may look basic. However, their biological processes are quite remarkable. One of the most outstanding features of a sea cucumber is its ability to slow down its metabolism in areas where oxygen levels are minimal. This is why sea cucumbers thrive well in deep seas.
12. Ocean Sunfish
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It’s a scientific wonder how Ocean Sunfish can survive low-oxygen waters despite their massive size. Popularly known as the mola mola, Ocean Sunfish have gills that absorb oxygen even in the most oxygen-poor ocean areas. Also, they can slow down their metabolism to accommodate extreme conditions.
