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Unit 12 Plankton – Drifters of the Sea Film – The Secret Life of Plankton General Info: • Plankton comes from the Greek word “planktos” which means drifter. Movement • By definition, plankton drift with the tides and currents. • Some have the ability to move on their own. For example, copepods are the fastest animal for their size- they move more than 500 body lengths per second. Two Types of Plankton • Phytoplankton which are autotrophs (plant-like) meaning they produce their own food. • Zooplankton which are heterotrohs (animal-like) meaning they eat other organisms Location: Epipelagic region of the ocean: • This location is near the surface where the water • • is warmer and lighter. The epipelagic is the top layer of the ocean from from 0 to 200m or 650 ft. It often corresponds with the photic zone, the region where light penetrates. Location: Epipelagic region of the ocean (con’t) • It is the shallowest part of the pelagic realm • The pelagic realm is the vast open ocean away from the bottom and the shore Location: Epipelagic region of the ocean (con’t) • Coastal (neritic): are waters that lie over • the continental shelf (small portion of the epipelagic) Oceanic: are surface waters beyond the continental shelf (most of the epipelagic). Energy comes from the sun • Nearly all primary production (photosynthesis) from • • the ocean occurs in the epipelagic zone Food produced sinks or is carried by the currents to other parts of the ocean. Autotrophs carry out photosynthesis by taking in carbon dioxide and converting it to organic food (glucose) and oxygen. Plankton have trouble remaining afloat • Organisms and their shells are more dense than • water and therefore should sink Coping strategies: – Increase water resistance- the greater the surface area the more resistance – Being small is helpful because small particles sink slower – Flat shape also increases surface area, as do projections and spines • Coping strategies (con’t) – Increase buoyancy • Some store lipids as vacuoles of oil (less dense than water) • Some use pockets of gas which is less dense than water • Regulating the amount of gas can move the organism up and down the water column Vertical Migration • Predators abound the epipelagic. Therefore, • some zooplankton sink to the dark depths during the day and rise to feed at night Most plankton have only limited horizontal mobility but high vertical mobility, which they achieve by regulating buoyancy Phytoplankton • Photosynthetic Autotrophs • – Greater than 95% of photosynthesis in the ocean – Produce nearly 50% of the oxygen in our atmosphere – Primary producer in the epipelagic- WHY? Gouped by size – Picoplankton- too small to be caught in nets – Net plankton- (nanno, micro, macro), large enough to be caught in nets Phytoplankton (con’t) • 2 Main Types—Diatoms and Dinoflagellates – Diatoms • Kingdom Protista • Most abundant phytoplankton in the ocean • Prefer temperate, polar, and nutrient-rich water • They are unicellular, although some gather in chains or clusters • Enclosed in a cell wall that is made out of silicon dioxide (glass) Diatoms (con’t) • They have a glasslike frustules which is a shell with tight- fitting halves. There is a wide variety of beautiful frustules! – Some frustules have perforations and spines that allow light to pass through and gasses and nutrients to enter and leave – Frustules from dead diatoms accumulate on the ocean bottom and are called diatomaceous ooze – Fossilized sediments of the ooze found inland are mined as diatomaceous earth which is used for polishing (toothpaste), insulating, and filtering (swimming pools) Diatoms (con’t) • Reproduce rapidly when conditions are good. Many species are depend on this food source and marine ecosystems depend on this primary production. Dinoflagellates • Kingdom Protista • Most abundant phytoplankton in warm, tropical • • waters Unicellular with a cell wall made of cellulose plates Most outstanding characteristic: 2 unequal flagella that direct movement in practically any direction Dinoflagellates (con’t) • Although autotrophic they also feed on other food • particles Reproduce by cell division – Huge surges of reproduction are called blooms – They produced Red Tides which actually turned the water red to red-brown Dinoflagellates (con’t) • Two Problems with Red Tides – Produce toxins which may cause fish to die or accumulate in the tissues of resistant organisms which can result in paralytic shellfish poisoning (PSP) which can be fatal to humans – As the bloom dies and decomposes, the bacteria deplete the dissolved oxygen from the water causing fish to die Dinoflagellates (con’t) • Some species produce light by bioluminescence • which can be seen at night in the open ocean Some species celled zooanthellae live in symbiotic relationships with other marine organisms such as coral. They release organic matter used by the coral and help in the formation of the coral skeleton. • Picopoplankton – Very small (less than 0.002 mm in diameter) and hard to catch – Still important in ocean primary production – Two types • Cyanobacteria • Coccolithophorids Cyanobacteria • Kingdom Monera, therefore prokaryotic • Contain chlorophyll (green pigment) and phycocyanin (blue pigment) • Most are microscopic, but can form long visible strands or mats • Likely the first photosynthetic organisms on Earth and contributed to the accumulation of oxygen in the atmosphere • Can also carry out nitrogen fixation- converting atmospheric nitrogen gas to usable from alike ammonia Sargassum • The seaweed sargassum is the largest • • species of phytoplankton Sargassum provides habitat to a wide variety of marine organisms including invertebrates, fish, sea turtles and marine birds. Commonly found on beaches along the Gulf of Mexico Zooplankton • Tiny planktonic animals • A few species are a critical link in the food web- they are herbivores, meaning they eat autotrophs • Most are carnivorous and feed on the herbivorous zooplankton Zooplankton (con’t) • They are divided into two groups: Holoplankton and Meroplankton • Holoplankton - spend their entire lives as plankton • Copepods – Most abundant zooplankton (70% or more) and may be the most abundant animal on Earth – They are crustaceans – Most eat phytoplankton and zooplankton (use bristled antennae) – Move fast to escape predators Euphausiids (Krill) • Shrimp-like crustaceans • Prefer colder waters • Filter feeders, eat diatoms, detritus, and zooplankton • Primary food for baleen whales in the Southern Ocean • Film Clip – Krill Power Jellyfish • Found in every ocean from the surface to the abyss • Have roamed the seas for 500-700 million years making • • them the world’s oldest multi-cellular animal No brain or central nervous system but respond to stimuli Have a benthic polyp stage and are therefore, meroplankton Jellyfish (continued) • One of the world’s deadliest creatures is the • Australian box jellyfish (sea wasp) which can kill an adult in a matter of seconds Australians have learned to swim wearing pantyhose on their arms and legs to protect against the box jellyfish Portuguese Man O’ War • not a jellyfish but a siphonophore, which differs from • jellyfish in that it is not actually a single organism, but a colony made up of many minute individuals called zooids. Since the man o' war has no means of propulsion, it is moved by a combination of winds, currents, and tides. Portuguese Man O’ War Meroplankton Only a portion of the lives are spent as plankton (larvae of fish and invertebrates) • Coral larvae • Starfish larvae • Squid larvae • Crab and shrimp larvae