Diatoms, photo ©synthetic algae of many sizes and shapes but mostly microscopic, with shells of silica, are among the oceans' primary producers--the first and most vital link in food webs.
Sunlit surface waters teem with billions and billions of tiny algae called phytoplankton. These photo ©synthesizers capture energy from sunlight and carbon dioxide from the atmosphere and sea water, and support most marine food webs. (On land, the major photo ©synthesizers are grasses and trees.)
Photosynthetic algae thrive in the bright light and nutrients of the ocean's upper layer. Consequently, other animals, including the fish we eat, congregate there to graze or hunt. By checking satellite images for changes in sea-surface color produced by large colonies of algae, fishermen can often find large concentrations of fish.
Food webs on land generally have few links: an insect eats grass, a mouseeats the insect, a snake or hawk eats the mouse. In the ocean, some food webs become long and complex.
Diatoms, photo ©synthetic algae of many sizes and shapes but
mostly microscopic, with shells of silica, are among the oceans' primary
producers--the first and most vital link in food webs.
photo © Oxford Scientific Films/Animals Animals
Copepods are the most numerous of grazers in the oceans--they
may even be the most numerous multicellular animals on earth. Most of them are
filter feeders that scoop up diatoms and other phytoplankton.
photo © Peter Parks, Norbert Wu
[pls check...]Surface dwellers: goose barnacles, Spirula shell, porpita, Portuguese man-of-war.
photo © Peter Parks/Animals Animals
Natives at these depths include:
Tripod fish rest their fins on the ooze or fine sand on the bottom, positioned like a tripod and headed into the current, to wait for their crustacean prey. Like many other deep-sea fishes, a tripod fish has both male and female organs so that a chance encounter can always result in mating.
Glass sponges get their name from their appearance out of water. As they're brought up from their deep habitats, their bodies collapse, leaving the skeleton, which is made of silica, looking like spun glass.
Giant isopods live on the shelf or slope of the Caribbean and Gulf of Mexico. They're scavengers that feed mostly on dead fish and invertebrates, but theymay also ambush injured prey. Chemical sensors on their antennae detect food.
Brittle stars are named for their ability to break off and shed their arms when attacked. They "walk" on their arms and feed mostly on floating organic matter or scavenge dead organisms on the bottom.
Gene Carl Feldman (gene@seawifs.gsfc.nasa.gov) last updated 15 August 1994
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