Most food chains in the ocean have crustaceans in them. They are prolific in every ecological niche in the sea. Sadly for them, few crustaceans are apex predators. Most are low on the food chain and are on the menu for many bigger, hungrier carnivores. In fact, trillions of crustaceans get eaten every day.
The largest population of crustaceans are the microscopic, ubiquitous Copepods. These live in the sea in prodigious numbers and are food for countless predators.
Every Comb Jelly consumes hundreds of Copepods daily. Some scientists estimate that Comb Jellies are one of the largest biomasses of predators on the planet. Crustaceans get hammered by all manner of predators, all day, and every day. Whales scoop up truck-loads of krill. Octopi feed on shrimps and crabs. Humans love their crustaceans too.
Life in the sea is tough. It is a “dog eat dog” world down there and the mere act of survival is a significant achievement. Death is never far away. Given the predatory pressure they live under, I marvel at the fact that any crustacean is able to survive at all.
Crustaceans are true gladiators. The spirit of the “knights in armour,” or the samurai warrior spirit of “Bushido,” are well and truly alive in the world of crustaceans. If you are sceptical, offer your finger to a large Blue Swimmer crab and see what happens. It would be like disrespecting a martial arts expert; you would never do it again.
Larger crustaceans have learnt to fight back. In fact, some have taken the art of survival to a very sophisticated level. They have developed ingenious methods of defence and attack. Let us examine the amazing cosmos of crustaceans and discover some of their incredible secrets.
The Gladiator
Lobsters are a strong contender for the title of “Greatest Gladiator in the Sea.” Every day brings another challenge, another threat, and another battle; to stay alive is to defeat another adversary and win. There is no prize other than life itself. Avoiding death is both an art form and a science to lobsters.
Lobsters have numerous enemies. In order to reach adulthood, lobsters would have fought and won a thousand battles - any battle lost is certain death. Adult lobsters are therefore powerful undefeated gladiators, majestic, battle-scarred survivors with an impressive arsenal of weapons.
This warrior spirit is universal in all crustaceans. I love the Squat lobster. Despite its small size (it is only about half a matchstick long), it stands up to me without fear. It waves its claws menacingly at me as if to say, “Come on, make my day!” Even though I am so much larger, this tiny display of threat was clear and I can sense its determination to fight.
Crustaceans have an amazing anatomy. I compare them to a knight of old, fully equipped for battle. Knights had full body armour, swords, knives, spiked balls, lances, hammers and spears. Lobsters too, have nearly impenetrable body armour. Their exoskeleton is made of chitin impregnated with protein and minerals. They possess offensive weaponry including claws, antennae and sharp spines. They gather information via their antennae and have a sense of smell that is almost as good as that of sharks. Some species have eyes that can see infra-red, ultra-violet and polarized light; some even have night vision. Mantis shrimps use low frequency sounds to communicate with other mantis shrimps. This is thought to be used for marking their territory, and possibly for attracting mates. Long distance sound wave transmitting capabilities were discovered by accident when mantis shrimps in aquariums were overheard making sounds, trying to communicate with mantis shrimps in other tanks. Lobsters are known to make a sound to warn other lobsters of nearby predators, using a technique similar to a violin bow sliding over a string.
These crustaceans are like our modern day soldiers with their Kevlar jackets, helmets, knives, guns, radio communication, binoculars and night vision goggles.
Essay & photographs by Mike Scotland (see OG Issue 33)