Animals constantly fight for survival - predators, fighting for breeding rights, and the environment are just some of the things animals face daily. These pressures have produced many spectacular evolutionary adaptations. Let's look at some amazing animals!
The Deep Sea Hagfish
The deep sea hagfish is an eel-like fish often observed by deep-sea submersibles; they are scavengers, feeding on the deceased bodies of fish and other animals that sink deep towards the ocean's bottom. They appear like very primitive fish, which is correct as they are the only known animal with a skull but no 'true' spinal column, just primitive vertebra.
Their unique survival strategy involves slime and lots of it! Should a predator attempt to eat a hagfish, special glands inside its body secrete slime, combined with seawater, which produces extremely fibrous slime. One hagfish can easily turn a bucket of seawater into slime. Most predators that make the mistake of trying to eat a hagish soon learn their lesson and won't try it again!
Another unusual fish is the pufferfish! With huge, cute eyes, their appearance captures many people's attention; they are, however, armed with many anti-predator abilities. The pufferfish will puff up like a living balloon, as their name suggests - preventing it from being swallowed by predators. Some species even have sharp spines that will jab their way into the predator's mouth; there have even been cases where the predator has died from a pufferfish stuck in their throat.
It doesn't stop there; many pufferfish have tetrodotoxin, which interferes with nerve signals, prevents muscle movement and will kill large animals if they successfully swallow the pufferfish.
One truly bizarre defence mechanism is self-destruction. The exploding ants found in Asia give their lives for the 'greater good' of the colony. The smaller workers of the ant species Camponotus saundersi and C. explodens can willingly rupture their body walls, which results in their toxins getting sprayed in all directions. The liquid acts as glue and has a corrosive property and a chemical irritant! Although the colony loses important workers, this strategy must be a net positive behaviour, or it simply wouldn't have evolved into existence.
One animal is so tough that it stands head and shoulders above nearly everything else on Earth (and even OFF Earth!)! The tardigrade or 'water bear' is a tiny, near-microscopic animal associated with damp places. These little animals are a maximum of 1.2mm long and have four pairs of legs with little hooked claws.
They have survived all mass extinctions on Earth, can happily go without water for over a decade (one specimen showed some movement after being 'dried' for 120 years!), and even survive the Antarctic's coldness and the Mariana Trench's deep-sea pressures.
In fact, they can survive a temperature range of 300 °F to absolute zero (-459.67°F!). It achieves this by cryptobiosis, where its metabolic activities almost completely halt - it's not dead but barely technically alive.
They have a special protein that coats their DNA and prevents damage from radiation. When added to human cells, this protein reduced radiation damage by 40%! They can repair DNA and produce fatty acids, which is something our bodies cannot do.
Here's the crazy part: on April 11th 2019, an Israeli moon lander 'Beresheet' failed its landing and crashed into the moo; its payload was several thousand tardigrades! Given their resistance, they probably survived the crash and entered that state of cryptobiosis and are, in fact, still alive. These animals are the greatest survivors on earth (and beyond)!