BIPOLAR SPECIES AROUND THE WORLD

The copepod (gaetanus brevispinus) exists all over the world, but is most commonly collected in polar waters where its cold water habitat comes closer to the ocean's surface. (Russ Hopcroft/University of Alaska Fairbanks, Census of Marine Life)

Bean-sized swimming snails (limacina helicina), seen here, live in both Arctic and Antarctic waters. They spin a mucus net off their paddlelike foot wings to trap algae and other small particles on which they feed. (Russ Hopcroft/University of Alaska Fairbanks, Census of Marine Life)

The shell-less pteropod or swimming snail (clione limacina) seen here is found in both Arctic and Antarctic waters and preys exclusively on its fellow shelled pteropods. (Russ Hopcroft/University of Alaska Fairbanks, Census of Marine Life)

This photo shows a chionodraco hamatus, one of the Antarctic's ice fish, which can withstand temperatures that freeze the blood of all other types of fish. (Russ Hopcroft/University of Alaska Fairbanks, Census of Marine Life)

A ghostlike sea angel (platybrachium antarcticum), seen here, goes through the deep Antarctic waters hunting the shelled pteropods (another type of snail) on which it feeds. (Russ Hopcroft/University of Alaska Fairbanks, Census of Marine Life)

In this photo, a marble-sized jellyfish (calycopsis borchgrevinki) is shown. They are one of the more common hydromedusae encountered in Antarctic waters. (Russ Hopcroft/University of Alaska Fairbanks, Census of Marine Life)

In this photo, a nemertean pelagonemertes rollestoni is shown hunting for zooplankton prey that it will harpoon with a dart attached to the tongue coiled within it. Its yellow stomach reaches out to feed all parts of the body. (Russ Hopcroft/University of Alaska Fairbanks, Census of Marine Life)

Census of Marine Life Arctic researchers have discovered more than 50 gelatinous zooplankton living in the Arctic, about a quarter of which are new to the Arctic Ocean or new to science. (Russ Hopcroft/University of Alaska Fairbanks, Census of Marine Life.)

The mimonectes sphaericus, shown here, is a commensial amphipod crustacean living on jellyfish and their kin in both the Arctic and Antarctic. The large swordlike antennae only occur on males. (Russ Hopcroft/University of Alaska Fairbanks, Census of Marine Life.)

Scientists say it's time to rewrite the textbooks. A marine census released Monday revealed that the polar oceans are home to far more species than had previously been thought. The new census, one of several projects of the Census of Marine Life (an international effort to catalog all ocean life), documented 7,500 species in the Antarctic and 5,500 in the Arctic. Researchers were also surprised to learn that as many as 235 species are found in both polar oceans. They say the discovery raises a number of evolutionary questions.
In this photo, sand fleas (amphipod crustaceans) are shown under shore ice in the Beaufort Sea. Ice-associated amphipods are a major food source for Arctic cod, the main prey for ice seals. (Shawn Harper/University of Alaska Fairbanks.)