Same Species, Polar Opposites: The Mystery of Identical Creatures Found in both Arctic and Antarctic Waters [Slide Show]

How exactly did identical marine species come to inhabit both the north and south polar regions?

BIPOLAR SPECIES: This chart divides bipolar species by their phyla. The gross majority are arthropods, insects of the sea whose exoskeletons protect their soft insides. The census is still tweaking the exact number of species... Census of Marine Life
LANCEOLA CLAUSI: Not much is known about Lanceola clausi other that it sometimes scavenges food and often ends up as fish fodder. "We know less than one percent of what lives below the upper 200 meters of ocean compared to everything above it," says Russ Hopcroft, project leader of the Arctic portion of the Census of Marine Life... Russ Hopcroft/UAF/CoML
GAETANUS BREVISPINUS: Gaetanus brevispinus is another cosmopolitan species, but occurs most commonly in the shallow waters near the poles. Closer to the equator it can be found as deep as 3,000 meters. This species may serve as evidence for another theory of bipolarity: Scientists think that species traffic between the poles along a deep-sea conveyor belt known as thermohaline circulation... Russ Hopcroft/UAF/CoML
GLOBIGERINA BULLOIDES: Kate Darling, a marine biologist at University of Edinburgh, genotyped the rDNA of Globigerina bulloides and two other species in 2000, the first time a scientist used genetics to verify bipolarity among foraminifera... http://dorsetmicroscopy.blogspot.com/
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HETEROKROHNIA INVOLUCRUM: Heterokrohnia involucrum , a type of arrow worm, is known to live everywhere in the ocean, even at the poles. According to most definitions, it's therefore not bipolar. Instead it's labeled cosmopolitan... Russ Hopcroft/UAF/CoML
LIMACINA HELICINA: One of the stranger bipolar creatures, Limacina helicina , aka the sea butterfly, spins a mucus web from the propellerlike feet that protrude from its shell. Once it traps enough algae it digests the mucus, along with its catch... Russ Hopcroft/UAF/CoML
MIMONECTES SPHAERICUS: Male Mimonectes sphaericus , jellyfish hunters of Earth's two poles, have antennae that look like bullhorns. Some scientists think creatures like these migrated across the oceans during the last ice age, 18,000 years ago... Russ Hopcroft/UAF/CoML
DIPHYES DISPAR: Scientists argue whether Diphyes dispar is a single animal or a colony of specialized single-celled creatures that serve the whole. The creature's hood houses long tentacles adorned with blossomlike hooks to catch other plankton... Russ Hopcroft, University of Alaska Fairbanks, Census of Marine Life
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CLIONE LIMACINA: Clione limacina is one of the centimeter-long creatures that live both in the Arctic and Antarctic. The shell-less snail resembles an angel, but hidden within its mouth are six feeding arms and a tongue that looks like a chain saw... Kevin Raskoff, Monterey Peninsula College, Census of Marine Life
POLARSTERN: The German vessel RV Polarstern cracks through the ice in the Antarctic on one of hundreds of voyages to map sea creatures for the Census of Marine Life. Data from voyages like this allowed scientists to compile a list of hundreds of identical species that live in Arctic and Antarctic waters, but possibly nowhere in between... J. Ziegler, Census of Antarctic Marine Life

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