Fish: Facts, Information, and Resources

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The fish world, like all life under the sea, is one that thrives on the diversity of species and the sheer variety of fish life: what they eat, where they live, how they move, and how they relate to the world around them. Some fish lead peaceful, solitary lives; some fish serve only as food for larger species; still other fish rule the waters at the top of their food chains. At their core, fish are all generally the same; look a little closer and you’ll find a stunning array of life; look even closer and the differences are enough to overwhelm even the most curious and knowledgeable of observers.

For starters, consider the huge range in sizes of fish. Their sizes tend to assert their place in the underwater pecking order, but even between the quarter-inch stout infant fish and the 51-foot whale shark lies a whole spectrum of sizes and shapes. However, these sizes and shapes tend to carry the same fundamental structure: an elongated body, a spine supporting a pair of fins (used for movement in water) and gills behind the eyes for breathing. Contrary to popular belief, however, fish don’t actually breathe water; they inhale it through their mouth, but the filaments inside their gills can extract the oxygen before pushing water back out through the gill openings.

Some fish, such as salmon, carp, and bass, have scales on their exteriors. While sharp and teeth-like, these are actually intended as defensive mechanisms against larger waterborne predators such as sharks (who also have scales, but for cutting through schools of fish rather than for fending off other predators). These scales come in handy, as fish have been proven to have heightened fear responses when sensing danger; this explains the old fisherman’s tactic of being absolutely silent while fishing. When a fish senses danger, its first response is to remain absolutely still, but even the slightest further agitation will send it fleeing.

The motion of fish is often described as “swimming,” which is actually not true at all. Rather, fish move through water by their backbone twisting their backbone, resulting in a push against the water that propels their body forward. Generally speaking, smaller fish tend to move faster, although several of the fastest fish are also the largest, such as the 10-foot sailfish (clocked at 100 km/h [68 mph]) or the 20-foot Atlantic blue marlin, known to reach speeds of 110 km/h (69 mph)]. Still, even those speed demons are no match for walking fish—those species capable of walking on land (and out of water), such as the mudskipper or the climbing gourani.

Still, all that motion tends to be for very limited purpose in a fish’s life, as most spend their time either breeding, eating, avoiding predators, or looking for a way to do any of those three things. Most fish reproduce sexually, but through oviparous means, i.e. fertilization occurs outside the body, with each parent fish simply dispersing its half of the genetic matter into the water surrounding the eggs, which then develop on the sea floor. Some fish, however, reproduce in more mammal-like fashion, such as the horn shark and the bullhead shark.

Reproduction requires food, however, and this is where the true hierarchy of fish is established. Many fish eat low-level plankton and algae, but those bottom-feeders in turn become food for more aggressive (and more protein-reliant) species, such as an anchovy or a bluegill. Those larger species get eaten by yet larger fish, perhaps a trout or a widemouth bass, who then become food for something like a marlin or a snapper, two very large fish usually eaten by sharks. In a strange twist, some sharks end up consumed by other sharks, but in most ecosystems the shark is considered the apex predator, i.e. the very top of the food chain. Many fish, especially bluegill and catfish, become food for non-fish creatures such as pelicans and seagulls or, more commonly, for humans.

Human fish consumption is older than history itself, with even primitive man learning to catch fish for survival. Today, some fish are considered a premium delicacy (such as swordfish, marlin, and snapper), while others are more common to delis and sandwiches, such as catfish, salmon, and tuna. Although the exact view of a fish’s fanciness varies by culture and locale, the methods of capturing fish have advanced considerably: where primitive man was lucky to catch one fish with his spear, later humans would attack larger fish with larger weapons such as harpoons and guns. Today, giant freighters use elaborate netting systems to sweep the water and capture literally thousands of catfish, pollack, bluegills, bass, tuna, and other sea creatures at a time. Yet for rarer species of fish, a whole cottage industry exists to provide adventurers and tourists alike with a chance to catch them on the deep sea; many a seafaring charter boat awaits the everyman looking for a chance to go toe-to-fin with a 12-foot, 5000-pound sunfish, 26-foot, two-ton beluga sturgeon, or even a 21-foot, 1,400-pound tiger shark.

And it is those boats, equipped with harpoons and massive steel beam reinforcements, that so perfectly illustrate the difference between fish and humans; a human would most likely seek out such a battle for sport, but contrary to popular belief fish (including sharks) only eat for survival. Yet in such a fight, the human relies on its tools while the fish relies on nothing more than its body and its environment, turning its weight into a weapon and its size into a secondary attack. Fish, while seen by many scientists as being fairly intelligent creatures, still lack the ability to either create or imagine, relying merely on instinct and an innate drive to survive. For larger fish, this means killing at will if necessary; for smaller fish, this usually just means scooting away to safety until the coast clears.

Resource by S.Henniman

I am an aspiring artist and writer from Phoenix Arizona. I enjoy golfing, skiing, college football, and hanging out with my two favorite girls (my wife and 4 year old daughter).

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