The ocean, which covers about 97% of the Earth, is teeming with life. Coral reefs house the greatest diversity of plants and animals in this watery ecosystem and provide essential life nutrients to the environment as well as safe harborage for the numerous creatures. The coral, an animal itself, provides refuge to turtles, eels, octopus, anemones, nudibranchs, fish, lobsters, crabs, starfish, sponges, snails, sharks and other creatures. It acts as a protective barrier to the shore to prevent erosion. The reef however is also home to several dangerous predators.
The Lionfish or Scorpionfish is an insatiable predator as it will eat just about anything that swims. It will hunt down its prey and force it into a corner using its large fins; then in a quick movement, it will swallow its prey whole. This fish gets its name from the long, striped spines found along its pectoral and dorsal areas. These spines contain a neurotoxin that is primarily used for defense, and is very painful but not fatal to humans.
The most venomous fish in the world is the Reef Stonefish. This fish is a master of camouflage as it resembles a piece of coral or an encrusted rock. With its large pectoral fins, the Stonefish can partially bury itself in the sand. When a fish or small crustacean swims by, the Stonefish lunges at lightening speed. The Stonefish is often mistaken for a rock and stepped on by people. The venom is extremely painful and before antivenom was developed in 1959, it killed many people in the Pacific and Indian Ocean regions.
The Tiger Shark is known as the "Great White" of tropical waters since it reaches a length of eleven feet, can weigh up to 2000 pounds and is extremely aggressive. It a nocturnal hunter known to eat a wide variety of things fish, turtles, squid, pinnipeds, birds and garbage! Its keen eyesight allows it to hunt in even the poorest visibility and highly sensitive sense of smell allows detection of the faintest trace of blood. The Tiger Shark can detect low-frequency pressure waves indicating the movement of other animals in the vicinity. This shark's aggressive hunting practices will have it circle and bump its quarry before attacking and devouring it completely. This shark has a reputation for attacking humans any time it comes upon them.
Another reef dwelling shark is the Bull Shark. This medium size, aggressive, impulsive animal likes to reside in the highly populated locations of tropical shorelines. This shark is not deterred by fresh or brackish water and will wander up rivers and streams. For this reason the Bull Shark is considered the most dangerous shark in the world. This animal like the Tiger and Great White Sharks have no qualms attacking humans. They too will bump their prey before attacking it and will eat whatever crosses its path.
Size does not always matter when it comes to dangerous creatures. The eye-catching Blue-Ringed Octopus although small in stature produces potent venom for which there is no antidote. The toxic nature of this venom is potent enough to kill 26 human adults.
The Cone Snail, a beautifully colored marine gastropod carries a potent conotoxin which it delivers through a harpoon-like tooth to its prey. When handled by humans, the delivery of the venom is painless and the victim may not be aware he has been poked. Without treatment the bite may become fatal. Scientists have been studying these conotoxins in an effort to use them for their painkilling abilities.
The Pufferfish or Blowfish is a funny looking fish as it uses small pectoral, dorsal, caudal and anal fins to move through the water. These short fins do not allow for swift forward motion so this creature incorporates a unique defense mechanism. It is able to quickly inflate its stomach with water or air if out of water, to ward of its attacker. This fish also creates a tetrodotoxin similar to that found in the Blue-Ringed Octopus and Cone Snail.
The Puffer's toxin is found in the skin and some of the internal organs but is considered a delicacy by the Japanese and Koreans. Poisoning from this fish is due to the improper handling of the meat for soup. This toxin is potent enough to easily kill 30 adult humans but has also been used as a recreational drug.
Most jellyfish are beautiful, ethereal creatures floating in the sea, but there are several species that can readily kill a human. The Box Jellyfish produces a deadly toxin that can immediately impact the human heart and nervous system. These opaque, pale blue cubes have 15 tentacles and can reach a length of ten feet. Their significant danger comes from the 5000 stinging cells on each tentacle. The sting is so painful that if the victim survives, he can experience discomfort and scaring from where the tentacle touched. This creature is mobile and can reach speeds up to 4 knots.
Another jelly, this time very tiny - the size of a thumbnail - can deliver venom so potent it can painfully disable a man. This tiny menace known as Irukandji Jellyfish, has stingers on its tentacles and its bell. The venom is injected by the tip of the stinger so the prick usually causes little concern. The venom produces Irukandji syndrome which elicits painful cramps in the extremities, sweating, nausea, vomiting, lower back pain, extreme headaches, racing heart rate and high blood pressure.
The most dangerous predator in the reef system does not reside there but makes a major impact nonetheless. This predator is highly intelligent, socially organized and highly selfish. He allows his wastes, chemicals and other pollutants to run into the ocean, increasing the temperature, poisoning the water and stealing the available oxygen. This predator is man.
Often he will poison the reef with cyanide in an effort to capture reef fish; ripping apart the reef to catch the temporarily numbed quarry. Too, he will use dynamite on the coral reefs to stun the fish he wishes to capture for food or for fancy. This completely destroys the reef including all the polyps from which the coral propagates.
Because the reefs play an important environmental and fiscal role in our world, we need to protect them and undo much of the damage we have already done.