Octopus by Roland C. Anderson Read Free Book Online

the first few months of their lives.
    â€”Roland C. Anderson
    Second, a huge part of plankton is made up of plants or other organisms that have chlorophyll and produce their own food. As a side effect of this process, the oceans produce 50 percent of the oxygen in the earth’s atmosphere, 95 percent of which comes from phytoplankton and 5 percent from bigger algae (kelp and seaweed) or the few marine vascular plants that live near shore. These organisms also provide habitat for marine animals, like mature octopuses and their prey. At the same time, the plankton absorbs carbon dioxide and uses it for metabolism. Because of the large volume and surface area of the oceans, two thirds of the earth, this activity provides an enormous buffer to the oxygen–carbon dioxide budget of the earth’s atmosphere. Carbon dioxide is currently increasing in the earth’s air despite this buffer, because we humans create huge amounts of it. Plants on land and in the sea can’t keep up with our industrial emissions. Plankton may also lessen the atmospheric ozone layer that contributes to global warming and bleaches the coral habitats in which many octopuses live. Clearly, the plankton in the oceans is immeasurably important for our survival.
    Third, plankton is important as an energy source. Dead plankton falls to the ocean bottom and collects there slowly, under ½ in. (1 cm) in 1000 years but amounting to thick deposits over millions of years. The rich oil deposits around the Gulf of Mexico are the result of plankton deposits on the floor of an ancient sea there millions of years ago. While it’s a harsh environment, some specialized octopuses such as the spoon-arm octopus live there.
    Fourth, both live and dead plankton can be ecological indicators. There are some plankton that exist only under specific climatic conditions and some that behave differently at different temperatures. By looking at fossil plankton, scientists can tell what the climate was in the past. For example, some foraminiferans, which are plankton with tiny, coiled shells, shape their shells in one direction in cold water and in the opposite direction in warm water. The percentage of left-to-right coiled fossil forms of these plankton in the ocean’s sediments can tell us the sea’s temperature at a particular time in the earth’s history (see plate 7).
    An example of how plankton balance can go wrong occurred in the 1960s. Lake Washington, an urban lake in Seattle, was becoming eutrophic:it was so rich from fertilizers in runoff and sewage that a blue-green alga bloomed in the freshwater plankton. That alga flourished, taking nutrients away from normal plankton, clogging the gills of fish, and reducing the clarity of the lake, so other organisms in the lake suffered. Swimming areas were closed. The lake was well on the way to becoming a muddy, sterile body of water, much like Long Island Sound is today, with few fish and green growing plants. Based on dire predictions of scientists monitoring the situation, the surrounding community was able to stop the processes leading to eutrophication by diverting sewage and runoff. Lake Washington is now a scientific success story: instead of being a turbid, dead lake, it is clean and clear, and the plankton are back to their normal state.
    Fifth, plankton can be lethal, even to some of the organisms that eat it. Or the plankton’s poison can be collected by and concentrated in the animals that eat it. One classic example is paralytic shellfish poisoning (PSP), or “red tide.” PSP happens because filter-feeding shellfish we eat, like mussels, clams, and oysters, collect the poisonous plankton. Carnivorous octopuses don’t accumulate these poisons and so aren’t poisonous to humans. The organisms that cause PSP are one of those pesky groups that seem to be both animal and plant, and they bloom in such huge numbers, they cause the water to be a rust-red color. In 1793, while