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?
![Same Species, Polar Opposites: The Mystery of Identical Creatures Found in both Arctic and Antarctic Waters [Slide Show]](https://static.scientificamerican.com/sciam/cache/file/7F1BBEE1-9DB9-4FC2-BD6D64A3C9CBA9CA.jpg?w=590&h=393)
Same Species, Polar Opposites: The Mystery of Identical Creatures Found in both Arctic and Antarctic Waters [Slide Show]
- 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. The final figures will come after every Arctic and Antarctic species is genotyped, a huge undertaking that began last year. Polar scientists hope their data will bring them closer to understanding the often surprising climatic and biological links that reach across the entire planet. 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. Along these currents, temperatures never rise above 4 degrees Celsius, allowing these ice-water creatures to survive the entire journey. 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. Species like this seem to appear out of nowhere to feast on algae blooms during the spring. "It's indescribable just how fantastic it is to look down a microscope. It's pretty similar to looking at Ghostbusters. You never know what's going to shuffle into view next," Darling says. http://dorsetmicroscopy.blogspot.com/
- 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. Scientists suspect that most bipolar species exist at other latitudes but haven't been found. An arrow worm uses hooks on its head to grab an unsuspecting passersby, then quickly swallows it whole. The worms are transparent, so under the microscope scientists can watch their prey being digested. 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. The proof could lie in the genetic variations among species on opposite hemispheres. 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. When it's done fishing, it reels in its hooks and swims away. Russ Hopcroft, University of Alaska Fairbanks, Census of Marine Life
- 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. It uses this apparatus to reach into the shells of other snails and devour them. Scientists are puzzled by how specialized ice-water creatures like these could have crossed warmer waters to reach the opposite point on the planet. 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. No one had realized so many creatures, many of them microscopic, have a mysterious bipolar link. J. Ziegler, Census of Antarctic Marine Life
