Octopus (31 page)

While working on their doctoral research on octopus lateralization and play in Austria, Ruth Byrne and Michi Kuba drove to Italy approximately twice a year to obtain octopuses. They bought octopuses (mostly common octopuses) from the Naples open-air fish market and the Naples Aquarium. To help defray the trip's cost, they also transported fish for several public aquariums in Austria. After filling their car with containers of fish and octopuses, they drove as fast as possible over the Alps from Naples to Vienna. Luckily, they were never blocked by snow. They used both battery-powered air pumps and air pumps powered by an inverter run off the car's battery. If the weather was warm, they ran the air conditioning full blast to keep the water cold. Near the end of the trip, late in the night, they met the curators of the aquariums in dark parking lots for quick transfer of the fish. The octopuses were acclimating to their new homes in less than fourteen hours, and survival rates were 95 percent.

Transportation time is a critical factor, because time and deteriorating water quality are the enemies. The objective is to provide optimal water quality and stability during the trip while minimizing trip time. If an octopus inks in a small volume of water, such as the amount in a shipping container, the ink will coat the animal's gills and it will suffocate. Ink, like other organic substances, will also cause the water quality to deteriorate. Since inking is an antipredator defense, smelling ink may also increase stress. If you collect your own octopus and it is prone to inking, let it ink as much as possible while in your net in the ocean, where you can easily flush out the ink. If transporting an octopus in containers that you have access to, such as plastic buckets in a car, bring some extra seawater so you can do water changes if the animal inks. A turkey baster can also be used to slurp up viscous ink blobs.

Low temperature acts as an anesthetic and slows down the metabolism
of poikilothermic invertebrates such as octopuses. A lower metabolism means the octopus breathes more slowly, uses less oxygen, and excretes less waste. Also, cold water holds more oxygen than warm water, and slows down the breakdown of waste products into ammonia. Although in absolute terms colder water is preferable to warmer water for shipping, avoid any sudden change of temperature or an extreme temperature. Rapid temperature changes cause additional stress. Octopuses shipped via airmail are put in insulated fish boxes so that the water temperature will remain stable when they are subjected to extreme temperature changes, like being left outside on the tarmac during a blizzard or sitting in the back of a dark brown delivery truck in the middle of a summer heat wave. You can include ice packs in the shipping container for species that prefer cold water and for summer shipments. In the field, buckets or coolers containing octopuses can be placed in the shade with a wet towel on top of them. Frequent seawater changes are advisable.

Some scientists use magnesium chloride (MgCl) to anesthetize cephalopods during handling prior to shipping. If you are experienced with this substance, the correct dose of MgCl can reduce inking and lower the stress and metabolism and therefore also the use of oxygen and the production of waste products. But using MgCl can be tricky, since the effective dose seems to vary with species and animal size, and too much is deadly. The NRCC is the only group we are aware of that regularly uses this method.

Animals that eat a lot excrete a lot of waste. In a closed system with no filtration, this waste will rapidly build up and have a negative effect on the water quality. When you are transferring an octopus from one captive environment to another, it is a good idea to not feed the animal twenty-four hours prior to the move. You can also use gentle aquarium-safe chemicals that absorb or neutralize ammonia and stabilize water quality. We have used Stress Coat effectively while transporting octopuses.

Octopuses need well-oxygenated water. In containers such as buckets and coolers placed in the back seat of the car where you can access them during transport, use an air pump to provide oxygen and keep the water circulating. For sealed shipments such as in air transport, octopuses are typically packed in two or three large individual plastic bags filled with one-fifth fresh seawater and four-fifths pure oxygen. These bags are then placed in insulated fish boxes. Most of the shipping cost is based on weight of the water, so using larger bags with extra oxygen provides even more of a buffer for delays and shipping stress at negligible additional cost.

Setting Up a Marine System

Readers interested in setting up a marine aquarium for an octopus should already be familiar with systems. We strongly urge those who have not kept a marine system but wish to keep an octopus, to first start with a simple marine system with fish in order to gain experience. Colorful but hardy fish such as damselfish are good choices for beginners. Those who have gained extensive experience with marine animal husbandry can often just look at a system and tell whether there are problems. There is no shortcut for learning this skill; paying close attention to water quality and to the behavior of the marine animals will help you acquire the knowledge you need.

Water with good quality, which can be made from fresh water and sea salt available at the pet store, is chemically close to the unpolluted seawater you would find in the open ocean. The pH of natural seawater is about 8.2. Natural seawater has over seventy known elements dissolved in it, mostly in trace amounts. Only a few make up 99 percent of all the dissolved salts. They and their abundance by weight are: chloride (Cl) 55.04 percent, sodium (Na) 30.61 percent, sulfate (SO
₄
) 7.68 percent, magnesium (Mg) 3.69 percent, calcium (Ca) 1.16 percent, and potassium (K) 1.10 percent. There are many trace elements in seawater, such as manganese (Mn), lead (Pb), copper (Cu), strontium (Sr), iron (Fe), iodine (I), and even trace amounts of gold (Au). Most of the elements occur in concentrations expressed in parts per thousand (ppt), parts per million (ppm), or parts per billion (ppb). Although the elements are present in small amounts, most are important for biochemical reactions, the chemistry of life.

In all of the world's oceans, the chemical composition of seawater is virtually the same. Only the total quantity of these elements—the salinity—changes slightly from place to place, and nutrients such as nitrogen compounds are present only in very low levels in natural sea water. These natural fertilizers are produced as waste products and from decomposition, and are dangerous in high levels. The world's oceans are vast and can dilute naturally produced waste products so they are never in high concentrations. Many photosynthetic organisms compete for these chemicals; they are essential fertilizers for primary producers, or plants that make their own food.

In closed systems, the water is recirculated, and up to three different
types of filters are used to maintain water quality: mechanical, chemical, and biological filtration. Biological filtration is simply filtration that provides a lot of surface area and good conditions for bacteria to grow. The simplest type of biological filtration is an under-gravel filter—a plastic plate that holds gravel and circulates water through it. The gravel gives bacteria a surface to attach to and the water circulation brings in new water to be filtered. The problem with these inexpensive filters in an octopus tank is that the octopus may find a way to get under the filter and thus out of sight, or may destroy it. Canister filters and wet-dry filters are better choices for biological filtration for an octopus tank, because they also have some mechanical filtration and, if you add carbon, they provide chemical filtration too. If the filters are cleaned regularly, the organics are removed from the system before they break down into ammonia, which reduces the load on the biological filtration. If they are not cleaned, they do little good. Chemical filtration with carbon, resins, and protein skimmers (foam fractionators) also reduces the load on the biological filtration. Instead of mechanically trapping particles that are removed, these directly remove undesired compounds from the water.

For an octopus tank, we advise that some level of all three types of filtration be used in a closed system. We also recommend the use of a protein skimmer, even a small one, which is an excellent way to maintain high oxygen levels, help remove ink, and provide chemical filtration.

Good water quality is nothing magical, but in closed systems, it is an ideal we strive for but never perfectly achieve. Aquariums hold more animal life in a smaller body of water than would exist in the wild. Even with the best filtration, the water in aquariums contains more nutrients from animal waste than natural seawater. When there are too many nutrients in the water, certain pest species are likely to grow and reproduce rapidly. Aiptasia (small brown sea anemones), bristle worms, and fast-growing algae are typical indicator organisms of excess nutrients.

In the worst case, a large bacteria bloom can form. In moderation, bacteria help break down the waste products, but when the tank is too polluted with nutrients, the bacteria go into overdrive, clouding the water and using up much of the dissolved oxygen. The resulting drop in oxygen kills more life in the system, which adds more nutrients to the water. The tank may go anoxic (no oxygen) in extreme cases, which will kill all life forms that require oxygen, and animals like an octopus that requires high levels of oxygen will be among the first to die. These conditions are likely to occur
in newly set up systems and in systems where too many animals are crammed into a small space.

Different species of animals have different tolerances of deviations from ideal water quality. Damselfish are among the most tolerant to less than optimal water quality. Corals, on the other hand, are much less tolerant of poor water quality. Octopuses are in the middle: they can live in surprisingly high nutrient levels but not as high as damselfish, and they need good oxygen levels and low levels of metals such as copper, which is especially deadly to them and most invertebrates. The necessary water quality in closed systems can be maintained by mechanical, chemical, and biological filtration and regular partial water changes.

Some public aquariums, like Hawaii's Waikiki Aquarium, California's Monterey Bay Aquarium, and Washington's Seattle Aquarium, and some wet laboratories such as the University of Hawaii lab on Coconut Island, the Aquatron at Dalhousie University in Nova Scotia, and the Bermuda Institute of Ocean Sciences, are able to keep some or all of their aquariums in an open system—a system in which natural seawater is pumped in from the ocean, circulated through the system, and then returned to the ocean. Open systems are best when the source of water is clean and stable and you desire the natural seasonal fluctuations in temperature and even plankton. At Monterey Bay Aquarium, they filter the incoming water very little, and the larvae of strawberry anemones and other marine life come in with the water, settle out in the tanks, and make a beautiful natural backdrop.

There are many benefits to open systems, such as little or no need for filtration, high water quality, and no need to wait to establish a bacteria filter. But there are some challenges as well. The water quality is only as good as the source. If the source water is affected by red tide or pollution, that's a serious problem with no easy solution. Most open systems are in areas not prone to red tide, and the owners pipe their water in from fairly deep so it is clean and free of pollution. Conditions will rapidly deteriorate if the supply of incoming water stops for any reason, such as power outages or pump breakdowns. Many large systems have backup generators and pumps in case of such emergencies.

In some rare cases, very cold water full of dissolved air or water compressed in a pump with air can become uncompressed or warmed up to the point that it holds more than the saturation level of dissolved gasses like oxygen and nitrogen. The water will get back to equilibrium—the excess air will start to form small bubbles in the supersaturated water—and if this
happens inside the body of an animal, it can be killed. Trickling the water through an off-gassing tower eliminates this problem.

If the water needs to be altered in any way, such as warming it or chilling it to a constant temperature, as is often needed in scientific experiments, open systems are incredibly inefficient. It takes a lot of energy to change the temperature of water; to do this and then flush the water through a system and then down the drain is also very wasteful. These systems can be made a little more efficient by transferring some of the heat or cooling from the wastewater to the incoming water. Still, open systems are best when the local water is reliably clean and has desired seasonal temperatures and other natural fluctuations. The primary advantage of open systems is that water quality can be extremely high and that waste products are literally flushed away.

Most systems are closed ones. In these, the waste products of the marine life build up until they are broken down or otherwise removed from the system. For closed systems, it is important to understand the nitrogen cycle. Many books have been written on maintaining marine aquariums, and most of the better ones spend at least a chapter discussing the nitrogen cycle. In a nutshell, dead animals and plants as well as excrement break down into compounds such as ammonia. Ammonia is the first and most deadly of the nitrogen compounds in the nitrogen cycle. If ammonia builds up, it will kill the animals in the system.

Bacteria in the genera Nitrosomonas and Nitrobacter serve the marine community well as decomposers. They break down nitrogen compounds by oxidizing them to obtain energy, and they eat toxic waste compounds and excrete less toxic ones. These bacteria don't appear overnight in a new aquarium. Well, actually they do, but in nowhere near the numbers needed. It takes about two weeks for enough Nitrosomonas to develop to be able to oxidize ammonia (NH
₃
) to nitrites (NO
₂
). Ammonia, being so toxic, prevents Nitrobacter bacteria from growing. Only when the Nitrosomonas bacteria have reduced the ammonia levels can the Nitrobacter bacteria begin to proliferate. They also take two weeks to oxidize the nitrites to nitrates (NO
₃
). The time it takes to build up enough Nitrosomonas and Nitrobacter bacteria is referred to as “cycling the system.” Nitrates, the end product of the nitrogen cycle, are the least toxic of the three nitrogen compounds. But they will continue to build up in the system in higher and higher concentrations until they are removed. Regular partial water changes are an easy way to keep nitrate levels down. Changing about 25 percent of the aquarium's
water every month is standard practice for marine aquariums. Nitrates, like all nitrogen compounds in the nitrogen cycle, are fertilizer for algae and fast-growing animals such as Aiptasia that depend on algae symbiosis. Systems high in nitrogen are therefore prone to blooms of algae and other pest species.