Plankton (1976)

[music] [music] [music] The sun is the prime source. source of [music] energy for life. A principle equally true on land or in the oceans. But a casual look underwater reveals nothing comparable to the huge mass of plant life that supports terrestrial [music] animals. Until the early 1800s, scientists had no idea what constituted [music] the basic food supply for life in the sea. >> [music] >> Creatures like the basking shark might have offered clues. Cruising slowly near the surface [music] with jaws wide open, the shark is feeding on minute animals and plants it filters from [music] the water. Imitating nature, marine biologists tow a fine mesh net underwater to collect samples of plankton, [music] an inclusive name for a great variety of organisms that drift in [music] the sea, most of them extremely small. The depth of the net is critical for many plankton migrate daily, sinking deep underwater during the day and rising near [music] the surface only at night. >> [music] >> Many plankton are all but invisible due to their transparency and small size. The apertures of this net are smaller than 1/100th [music] of an inch. And yet many plankton are smaller still and even finer nets or other techniques [music] are necessary to collect them. >> [music] >> Incredible numbers of plankton [music] swarm in the sea. Some are plants, some animals, and some combine characteristics of both. They constitute a vast and largely invisible universe of sea life. Without [music] its rich and varied populations of plankton, the sea would be virtually lifeless. Considering the importance of plankton, we know remarkably little about these intricate and essential organisms. The basic and by far the most numerous plankton are minute drifting plants drawing chemicals from the water and energy from the sun. They constitute the basic food supporting all other forms of [music] sea life. Responding in complex ways to the changing seasons, [music] they appear by the billions in spring and fall. Typical of animal plankton forms are radolaria, an abundant and [music] especially beautiful order of plankton. From apertures in their skeletons, protoplasmic filaments protrude, acting as tentacles to entrap food plants [music] and animals that drift within reach. A model of a radiolaran skeleton. Its intricate [music] symmetry no less remarkable than the millions of tons of them that lie on the ocean bottom accumulated over millions [music] of years. Larger and probably less numerous than radolarans. Terropods are predatory marine snails. Terrapods [music] like all plankton have special means of keeping afloat. Some plankton [music] have passive means of flotation, but the terrapod must flap its fragile wings in a tireless lifelong fight against the force of gravity. A marine worm larvae, prey in the plankton world, is captured by amphana, a tiny jellyfish. Countless such encounters fuel the complex food chains that lead from such minute plankton up to massive sperm whales. [music] Within a few hours, the worm will be almost completely digested and amphana prepared to trap other prey. >> [music] >> Many plankton are almost totally transparent. Even predators like the sea gooseberry benefit from invisibility in a world where virtually every species is food for dozens of others. [music] Sea gooseberries and their relatives, the barrel-shaped baro, are capable of swimming movement. Virtually all animal plankton perform a remarkable vertical migration, rising at night, [music] sinking during the daylight hours. A galma, a jellyfish related to the Portuguese man of war, belongs to the plankton community. A colonial animal. It is regarded [music] by biologists as a confederation of individual organisms, each with a specialized function. A flotation organ near the top helps stabilize a galma's depth in the water. Propulsive water jets ring the lower body, pointing in all directions and [music] maneuvering a galma, much like small directional rockets on a spacecraft. Digestive organs, like a mass of small stomachs, cluster around the lower parts of a Galma's body. Below the long stinging tentacles which capture a galma's prey. In effect, the tentacles form a kind of floating trap which sweeps wide areas of water even if a galma's movements are slow and sporadic. Many planktonic animals are the laral or younger forms of larger and more familiar sea animals. But some resemble their parental forms so little that scientists who first described them considered them separate species. [music] Now and only slowly is confusion clearing and larve traced to their adult forms as for instance many kinds of shellfish. Most larve like many open ocean plankton haven't yet been successfully raised in aquariums. So tracing the [music] progressive and very different stages of laral growth from specimens collected in the open [music] sea is very difficult. Only an expert after long study can trace the development of a larvae into a particular species [music] of crab. The first laral stage of the barnacle. Active and free swimming and once thought to be a totally unrelated species. Drifting with the ocean currents, the larvae may travel for a while, gradually developing into its [music] adult form. Full grown, the barnacle is fixed in place for life. and no longer considered plankton. Indeed, it now feeds on plankton, sweeping in minute plants and animals that much resemble its own larvel children. Among the largest planktonic animals are the jellyfish. The word plankton means that which drifts. And any sea creature not capable of making strong headway against ocean currents is generally regarded as belonging to the plankton community. [music] Even some newborn fish can be regarded as plankton. Some too weak and vulnerable to thrive alone stay close to a drifting jellyfish while they are young. The jellyfish affords them protection against predators and they in turn may lure prey into the jellyfish tentacles. When grown, they will swim free [music] and no longer belong to the plankton community. [music] >> [music] >> Mysteries abound in the world of plankton. The single eye of this copapod, [music] one of the most abundant of animal plankton, is remarkable in its color and internal [music] design. No one so far can explain exactly how it works or why it has evolved. This planktonic [music] plant is called basilia paradoxa. Paradoxa because its mysterious [music] sliding movements have yet to be fully explained. Somehow they must serve a vital function, but it has yet to [music] be discovered. >> [music] >> First photographed when this film was made, this tiny, brilliant planktonic animal has yet to be >> [music] >> identified and may never have been seen before. Mysterious and full of unsuspected [music] beauty, plankton are vital to the nutrition of man. This critical link in a chain of energy exchange [music] that begins with the sun and ends with the food we harvest from the sea abounds with mysteries and unsolved problems. The world of plankton is a world yet to be fully explained and [music] explored. [music] >> [music]