Ocean in a Box

With the clownfish darting around vibrant green plants and red coral, the 180-gallon saltwater aquarium in my son’s pediatrician’s office always grabs my attention. For a moment, I get to see how life under the sea operates—and I’m amazed!

Maintaining a saltwater aquarium is challenging. Many aquatic species require extremely specific pH, salinity, temperature, and lighting. If something is slightly off, they die. From the rocks to the water temperature, each aspect requires constant care.

If this sounds hard, imagine the complexity of maintaining the worldwide ocean ecosystem. God’s self-maintaining aquarium—over 300 million trillion gallons—supports hundreds of thousands of species and countless specimens. Such divine expertise in designing a stable habitat for sea creatures boggles the mind!

Illustration by BIG MOUTH

1. Water Pump—Water pumps, called powerheads, create a current that circulates and oxygenates the tank water. Moving water keeps waste from settling on the bottom. It also encourages exercise for the fish and deters algae from overgrowing. In the ocean, currents do the job. The Bible says that God controls these life-giving “paths of the seas” (Psalm 8:8). At the earth’s poles, salt sinks into the water below the ice. That dense, highly salty water then sinks to the ocean floor. As the saltwater sinks, new water replaces it, creating a current that moves around the globe. It enables the growth of algae and seaweed and regulates water temperature.
2. Filters—A dirty aquarium stresses the fish, increasing their susceptibility to disease. So filters are essential for removing waste and toxic chemical buildup. In the ocean, the water is filtered naturally by many means. Ocean water upwells and brings cooler, clean water from below to the top. Sea life also helps keep the water clean. For example, a single oyster filters about 50 gallons of contaminated water a day.
3. Heater—Even minor temperature changes can kill fish, so aquarium owners must keep a constant eye on the temperature, adjusting light and heat as needed. The oceans have their own systems of adding and circulating heat: hydrothermal vents at the ocean floor, global and seasonal variations in the sun’s intensity, and currents that circle the globe.
4. Coral and Plants—Rocks and plants aren’t just there to spruce up the place, whether in the aquarium or the ocean. They give fish a place to hide and food to nibble. They also help stabilize the water chemistry. For example, the stony formations made from coral release calcium, which maintains the ocean’s stable pH level. The coral, though dead, is called “live rock” because colonies of microorganisms flourish there, cleaning the water and pumping out oxygen. Marine plants and algae are, in fact, the planet’s primary oxygen factories, supplying 70–80% of earth’s oxygen needs.
5. Tank—From hexagons to cylinders, tanks come in many shapes. Oxygen and carbon dioxide exchange at the water’s surface, so the larger the aquarium, the better. Of course, God’s “aquarium” is the largest of all, covering 71% of the earth’s surface. The ocean’s dynamic surface—wind, waves, and currents—dramatically increases this all-important gas exchange.

Escape Plan. If an aquarium isn’t properly maintained, the fish need an escape plan. But their options are limited. Uncleanliness places so much stress on firefish gobies that they’ll jump out of the tank—with tragic results. In the ocean, God made sure fish can just relocate if they’re unhappy with their living conditions.

Cleanup Crew. Have an algae problem in your saltwater aquarium? Hermit crabs are at your service. Since they’ll eat just about anything while scouring sand and rocks for food, hermit crabs unknowingly clean toxins in aquariums just like they do in the ocean.

Social Butterflies. Pixar wasn’t making it up. Like fictional Nemo, clownfish live with other sea creatures such as puffers and live corals. But not all fish are so chummy. Unlike the ocean, an aquarium offers limited space for creatures to establish territories, so aquarium owners need to carefully select the tenants.

Salinity Regulation. Saltwater fish need a stable amount of dissolved salt—not too much or too little. A hydrometer helps measure salinity, so the owner knows when to dilute the saltwater. So in the ocean God put in place several natural systems to regulate the salinity level: erosion from the continents adds salt, while the seafloor chemistry and organisms disperse and remove it.

Article was taken from Answers magazine, September–October, 2019, 36–37.