Imagine spending every moment of your life beneath the surface, with very little to protect you from predators. For marine animals of all kinds, the quest for safety never stops, and the survival strategies these creatures have adopted are as unique as they are fascinating. Whether you’re an underwater photography enthusiast hoping to gain greater understanding of your favorite subjects, or if you simply want to learn more about how marine animals survive and thrive in a challenging environment, the many ways they approach life underwater are certain to intrigue.
Let’s Stick Together: Schooling
One of the most prevalent survival strategies is schooling – that is, sticking together in large groups. Many fish begin life in schools then head out on their own or swim in small groups after they’ve grown to adult size, but many others spend their entire lives in shoals numbering thousands or even hundreds of thousands of individuals.
By sticking together and swimming in tightly controlled formations, schooling fish give many predators the impression that they are a single large creature. Thanks to this optical illusion, many predators ignore large schools of fishes and grant them safe passage.
Even when predators attack a school of fish, the probability that a single member of the school will be hunted down and killed is much less than the same fish’s chances of ending up as lunch, had it been swimming on its own. By concealing themselves within a large group, individual fishes increase their chances of survival.
While casual observers might think schooling is a kind of random instinct, various fish in the school have specific jobs that contribute to the safety of the group. The fish along the school’s outer edges act as sentinels, watching for danger and rapidly alerting the rest of the shoal of approaching threats. Using special receptors, the rest of the fish are able to take rapid evasive action.
Hiding Out: Camouflaging
Many fish and other marine animals have the ability to camouflage themselves within their natural surroundings. Some are able to take on the appearance of corals or rocks, appearing to be part of the reef environment. Others are able to blend in seamlessly with the bottom topography – they are very difficult to spot, even when you’re staring right at them!
Some fishes are shaded so that they blend in with the water column; when viewed from above, they blend in with the bottom or with the water’s color; when viewed from below, they blend in with the light that penetrates the water’s surface. This is such an effective camouflage strategy that military forces often paint their ships and aircraft in a similar manner, making it much more difficult for observers to spot these potential targets.
Many fish have beautiful patterns of spots, strips, and bars. When striped fish swim together, the stripes on their bodies create an optical illusion, making it very difficult for predators to differentiate between individuals. Fish with vertical bars on their bodies are able to camouflage themselves among plants growing on the seabed. The light colored areas between bars blend in with the water column, making it hard for predators to spot their quarry, particularly when they are resting.
Escaping with Ease: Speed
Some fish, particularly those that travel singly or in very small groups, are equipped with the ability to swim at high speeds in order to evade larger, slower-moving predators. Tuna, jacks, and mackerels are able to accelerate rapidly and swim fast; many adolescent sharks are also able to evade large predators including members of their own species by disappearing at a high rate of speed.
Prickly and Painful: Protective Spines and Scales
Many marine animals have sharp spines that protect them from would-be attackers. We see many of these creatures while diving; sea urchins, surgeonfish, puffer fish, and balloon fish are just a few of the animals that rely on sharp spines for protection.
Some animals don’t have sharp spines, but they do have very hard scales that act like armor, protecting them from predation. Seahorses and boxfish are two examples of fish that have tough exteriors that present predators with an overly difficult dining experience; instead of attacking these armored animals, many predators choose prey that’s easier to eat.
Poisonous Prey: Protective Venom
As a rule, we tend to think of venomous marine animals as creatures to steer clear of, and most predators think the same way we do! Lionfish, stonefish, and scorpionfish are just a few of the species which are equipped with special glands that secrete venom that packs a powerful sting that is capable of incapacitating potential predators. These animals will sting on contact; in contrast, stingrays, which also have venomous stingers, must actively defend themselves when threatened.
Protective Markings: Heads or Tails?
Some fishes, particularly members of the angelfish and butterfly fish groups, have dark spots around their eyes as well as dark spots toward their tails. These spots look almost identical to the ones around the eyes, and they create confusion within a predator’s mind; it is literally unable to tell heads from tails! These markings look lovely to us, but they also serve a purpose: they often cause predators to attack from the rear, enabling their prey to escape with only minor injuries or in some cases, to get away completely unscathed.
Into Thin Air: Taking Flight
Some marine species are able to leap great distances over the water’s surface. Some rays have this ability, as do flying fishes. These animals are equipped with fins that make swimming efficient, and which also make skipping across the surface easy. Predators without the same ability are left behind, while “flying” marine creatures escape with their lives.
Safe at Home: Burrowing
We humans often feel safest in our homes, with locked doors between ourselves and the harsh world outside. The same is true for many marine animals; they dig burrows and hidden chambers where they are almost completely protected from attack. Tilefishes and gobies, razorfishes, and eels are some examples of marine animals that use their burrows for protection.
Zapping Attackers: Electricity
A few marine species have the amazing ability to generate electricity and shock attackers. Electric eels and electric rays protect themselves in this manner, ensuring predators steer clear.
With so many fantastic defensive mechanisms available, marine animals are able to live in balance with one another. There are thousands of undiscovered species in our oceans; as these animals are discovered and as we learn more about them, we are sure to learn even more about how they survive. Still, every animal has a special story to tell. Next time you’re diving, take a closer look at the animals you encounter, and you’ll gain even more knowledge about their lives.