Octopus by Roland C. Anderson Read Free Book Online Page A

exploring the North American West Coast, the crew of explorer Captain George Vancouver ate some mussels from the shores of British Columbia. Four of the crew became sick, suffering numbness and tingling of the arms and legs followed by paralysis, and one died. In modern times, few people are affected by PSP, since commercial shellfish harvests come from safe water and at safe times, and the public is notified of red tide blooms. Red tides usually occur in the summer: there’s an old, usually reliable adage that says to only eat oysters in months with an R in them. Red tide can kill marine animals too; a red tide bloom off the coast of Florida recently eliminated a local population of pygmy octopuses that ate infected shellfish.
    While dead plankton and its waste products are constantly falling down through the ocean to the bottom, continually adding to the sediment, living plankton must remain in the rich, well-lighted surface layers. This is particularly important for a plant or an animal with chlorophyll, which needs the energy of sunlight to drive photosynthesis. Light is absorbed in the upper 1000 feet (300 m) of the ocean, and the lower depths are essentially black.
    Although plants and animals of the plankton, including cephalopods,use several methods to stay near the surface, many members of the plankton have no special adaptations for staying afloat. They slowly sink down through the ocean’s surface layers and die when they get too deep to photosynthesize or find food. But they are fast and prolific spawners, and they reproduce before they sink too deep. Their eggs and sperm are buoyant, so they float to the surface, where fertilization takes place and the whole life cycle begins anew. Organisms that go through this cycle (such as diatoms) are usually small.
    Other planktonic organisms are adapted in some way to making themselves buoyant or to hover, maintaining their position. These adaptations can either be active or passive. One common passive method is to increase the ratio of the area of the outer surface to the volume, thus making the animal or plant more buoyant or likely to sink more slowly: for example, some organisms have spines or other projections on the outer surface that provide resistance to falling through the water. Octopus paralarvae have bundles of bristles, Kölliker’s organs, sticking out of the skin that may do this. And, paralarval Atlantic long-arm octopuses (Octopus defilippi), which have a specialized, long, third arm pair, can extend these arms and drift in the surface waters. Planktonic octopus paralarvae with these adaptations look a bit different from the adults, but they are still recognizable as octopuses.
    Another way members of the plankton increase buoyancy is to produce a substance that is lighter than water and retain it in their tissues. Many animals and plants of the plankton do this by secreting a type of oil, and oil is lighter than water. This oil eventually winds up as the hydrocarbons of petroleum deposits. The oil-rich blubber of whales helps offset the sinking of the whales’ heavy bodies and also keeps them insulated from the cold. Many planktonic organisms have oil globules in their cells, which are visible when they are examined under a microscope.
    Another substance used to keep plankton buoyant is ammonia, again lighter than water. Ammonia is primarily used by the large squid species, including the giant squid (Architeuthis dux), in their tissues, although the glass squid (Cranchia scabra) concentrates ammonia inside a special organ. The ammonia in the tissues of these squid makes the living or dead animals smell pungent. Dead or dying giant squid floating on the ocean’s surface smell particularly foul. The ammonia in these giant squid also makes them inedible—there will be no giant squid calamari. Clyde Roper (1984),expert on the giant squid, once sampled a cooked piece of this monster and remarked that it was really terrible tasting