Survival strategies

Octopus have inventive survival strategies

Phil North

It's a tough world out in the seas & oceans. Predators come in all shapes and sizes and use speed, strength, deception and sometimes outright determination to catch their prey.

But its not all bad news for the smaller fish that are vulnerable to attack. They have devised a whole host of cunning strategies to avoid ending up as someone else's lunch.

Some team up with others, while some prefer to go it alone using disguise, deception or good old-fashioned deceit.



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Strength in numbers

Schooling
Many smaller fish gather in schools for protection. It may seem a slightly misguided tactic - bringing attention to yourself by gathering in a large group, but strength in numbers is not such a bad thing. Lost within a school of thousands, you would need to be very unlucky to be singled out for lunch. 

There is another benefit too though. A seething mass of constantly moving fish has a tendency to confuse predators and thousands of flashing silvery tails can temporarily dazzle the attacker so that they make a blind & badly judged lunge. This strength in numbers tactic is used by many fish, from Glassfish and many other kinds of Baitfish to Snappers & huge schools of Sardines. Even Barracuda school for this reason. Clever hunters, such as Dolphins, can easily defeat this approach, but it still provides successful protection against many would-be predators.

Teamwork
Sometimes, entirely different species work together to avoid becoming prey. A classic example is the partnership between a Shrimp and a Goby. The shrimp is blind, so he cannot see a predator approach. Luckily for him though, he is a very good housekeeper, which is something that is very important to his Goby Guard. The Goby stands on alert in case of a predator, his tail always in contact with his blind housekeeper. If he senses danger, a flick of his tail will warn the Shrimp and they will both dart into the den lovingly prepared by the blind shrimp until the danger is passed.

Big Friends
Some enterprising fish simply make friends with a bigger fish, offering cleaning services in exchange for protection. Many large fish, such as Manta Rays, Sharks & Whalesharks have Remoras in attendance. The Remoras keep these giants free of parasites and in return, they get a free ride and a big scary friend to ward off predators. Pilotfish use the same tactic with many species of Shark and Shrimps often live happily in the lair of a Giant Moray, safe in the knowledge that their services are just too useful to their host to ever be considered prey.

Become Indispensible
Some fish manage to survive simply by being indispensible. Small fish that provide vital cleaning services are valued so highly by potential predators that they are almost immune to attack. Cleaner Wrasse & Cleaner Shrimps run cleaning stations which other fish visit to have parasties removed, avoiding the tempatation to have a snack while they are visiting as the service is so worthwhile. Look on almost any Moray Eel and you will see small Shrimps or Wrasse that seem to flaunt themselves in front of the Moray's open jaws without a care in the world - safe in the knowledge that they are far more useful to their host alive than dead.

Schooling together is a survival strategy

Tara North


A magician's touch

Camouflage is an effective surival strategy

Phil North

Camouflage
The art of appearing invisible is a popular way to avoid predators. Many times, camouflage acts as both a tactic of attack and defence at the same time. 

Flounders are masters of camouflage, blending in perfectly with their background - a tactic that they use both to find food and avoid being eaten. Ghost Pipefish are often almost undetectable in soft corals and feather stars and it is possible to stare at a Seafan for hours, without even noticing the Pygmy Seahorse hidden within. Some juvenile Batfish appear just like a leaf that has fallen off a tree.

Deception
If you are not scary or poisonous, one of the most cunning ways to avoid being lunch is to look and act like a dangerous or poisonous species. Brightly coloured juvenile Harlequin Sweetlips constantly dance and weave in an attempt, it is believed, to mimic a flatworm. This tactic works as flatworms carry poisonous toxins that predators soon learn to avoid. Juvenile Shaded Batfish, with their black bodies and bright orange fins also look remarkably similar to Flatworms. 

Many fish have 'false eyes', which will not avoid attack, but will deceive predators into attacking in the wrong place, giving the prey more chance of escape. The master of deception though is the extraordinary Mimic Octopus. These small octopus have a repertoire that includes Seasnakes, Lionfish, Flounders and more, allowing them to take on whatever guise they believe will work best to deter their would-be attacker.

Fireworks
Some critters, especially those of the deep sea, have the ability to let off tiny fireworks of bioluminescence, which confuse and bewilder predators. By shooting these tiny packages of bioluminescence into the surrounding darkness, they buy themselves crucial seconds to escape while their attacker is distracted - in just the same way that a flare can be used to prevent a missile hitting its true target.

It was once said that necessity is the mother of all invention. Nowhere is this concept more true than in the underwater world, where the need for survival has led to some of evolution's most brilliant solutions.



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