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The WISSARD borehole operation on the Ross Ice Shelf

The WISSARD borehole operation on the Ross Ice Shelf

Outside my window, New York City is experiencing a blizzard. The city is on high alert: the mayor is issuing all sorts of proclamations while, at the grocery store, a horde was stripping the shelves bare. Meteorologists and weather scryers warn that the city could be in for up to 36 inches of snow!

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Being forced to live under 3 feet of snow is an alarming prospect to me, but it is nothing for the life forms which were just discovered by a team of scientists exploring the extreme ecosystems of Antarctica. The Whillans Ice Stream Subglacial Access Research Drilling (WISSARD) project has just drilled through the Ross Ice Shelf—a gigantic sheet of ancient ice which covers an area approximately the size of France. The amazing (albeit stupidly named) WISSARD team drilled through 740 meters (2,430 feet) of shelf ice by means of a specialized hot water drill in order to lower a cylindrical robot submarine into this hidden sea. The insertion point for the probe was near where the ice sheet, the ocean, and the long-buried lands of Antarctica all meet–nearly 850 kilometers (530 miles) from the open ocean. At the converging point of ice, rock, and water, there are vast “grounding lines” of ice which attach the glaciers to the floating Ross sheet. Below the ice, a constant rain of rocks ranging in size from microscopic dust to house size boulders fall upon the sea floor. The temperature of the sea water is 28 degrees Fahrenheit (minus 2 degrees Celsius).

An ice fish and the robot submarine looking at each other

An ice fish and the robot submarine looking at each other

The scientists had speculated that fresh melt water from inland would create an estuarial environment beneath the ice. They found no evidence of that, but they did find all sorts of strange lifeforms. The barrage of rocks keep any sessile lifeforms from finding a home in these waters, but hardy motile sea creatures live there including fish, jellyfish, and amphipods (hardy crustaceans which thrive in extreme environments). The newly discovered Ross fish (which yet lack a name) are the southernmost known fish of the world. They are translucent and pink and measure about 20 centimeters (8 inches) long. As with the crazy underground catfish of South America (which live below the water table), the existence of these ice fish raises an immediate question: what do they live on? The sun shines little through half a mile of solid ice, so what do microorganisms as the base of the food chain use for energy? These organisms do not rely on “cold seeps” (which we explored in a previous post), but the answer is not entirely unrelated.  Scientists speculate that the geological upheaval releases nutrients in the form of carbon. It seems that an ancient fossilized ecosystem eroding away into the ocean. The strange fish and sundry invertebrates of the Ross Ice shelf may ultimately be reliant on fossil fuels—which makes them our spiritual brothers for, in this era of cheap frack-gas humankind is more tied to fossil fuels than ever [looks at snow outside and turns up heat].

A fish seen at the Ross Ice Shelf grounding (Deep-SCINI UNL, WISSARD)

A fish seen at the Ross Ice Shelf grounding (Deep-SCINI UNL, WISSARD)

Monito del monte (Dromiciops gliroides)

Monito del monte (Dromiciops gliroides)

Monito del monte (Dromiciops gliroides) is a tiny arboreal marsupial native to the temperate rainforests of Chile and Argentina.  The name “Monito del monte” means “little monkey of the mountain” and although the tiny marsupials are not even remotely related to primates, they are clever and deft.  During the cold winter months the animals hibernate in little ball-like nests which they build out of waterproof leaves and line with moss.  Like the more familiar marsupials of Australia, the females have pouches where they nurse their litters of up to four offspring.

Monito del monte (Dromiciops gliroides) with tree snail

Monito del monte (Dromiciops gliroides) with tree snail

The adult animals prey on small invertebrates which live in the trees but they also supplement their diets with fruits and seeds.  A particular species of Loranthacous mistletoe (Tristerix corymbosus) has evolved in conjunction with the monito del monte and relies entirely on the animal to spread its seeds.  This is noteworthy because “scientists speculate that the coevolution of these two species could have begun 60–70 million years ago.”  The monito del monte is not some rodentlike offshoot of the marsupial line, it is a close analog (and direct descendent) of the basal line from which all marsupials spring.

Monito del monte (Dromiciops gliroides) with human for scale

Monito del monte (Dromiciops gliroides) with human for scale

In fact, like something out of a gothic novel, the monito del monte is the only species of the sole genus of the last family of the exceedingly ancient order Microbiotheria.    During the dawn of the dinosaurs, South America, Antarctica, and Australia were amalgamated together as a supercontinent Gondwana.  The offspring of the original marsupials spread from South America, across Antarctica, to Australia, but then the continents drifted away from each other and evolution took a different direction in each ecoysytem.  The monito del monte remained in the same sort of forest as its ancestors and changed least over the years.

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Speaking of which, the Valdivian temperate rain forests where the monito del monte lives today are themselves a remnant of the great forests of Gonwana.  The trees and plants which live there now are most closely related to the living plants of Australia, New Zealand, & New Caledonia, but they are closer still to the fossilized forests which lie beneath the glaciers of Antarctica.  The Valdivian forest is the closest thing surviving to the great forests which once covered the iced over southern continent.

Valdivian Temperate Rainforest

Valdivian Temperate Rainforest

The ancestors of the monita del monte—and of all other marsupials—originated in South America and spread through the Antarctic forests to Australia before the continents drifted apart during the Cretaceous.  When the continent broke from Australia and drifted south into the prison of the circumpolar current during the Eocene, the forests died and Antarctica became an otherworldly landscape of ice.   Yet if you wish to know what the sweeping temperate forests of Antarctica were like you can visit Chile and watch the most ancient marsupial among the tree ferns and araucaria trees of the Valdivian forest.

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A Crabeater Seal on an Iceberg (photo by Rob Wilson)

A Crabeater Seal on an Iceberg (photo by Rob Wilson)

The crabeater seal (Lobodon carcinophagus) is a pale-colored seal which lives on the pack ice around Antarctica.   Adult crabeater seals have an average length of 2.3 meters (7 and-a-half feet) and weigh around 200 kg (440 pounds) however the largest male crabeater seals can weigh up to 300 kg (660 lb).  The seals’ mass alters considerably over the course of a season as they gorge themselves in preparation for lean times (or—in the case of mothers—for nursing).  Like other Antarctica seals, crabeater seals have slender bodies and long snouts.  They are gifted swimmers—a talent which allows them to escape their two main predators, killer whales and leopard seals.  They infrequently venture beyond the continental shelves of Antarctica (although very rarely one is spotted at New Zealand, Patagonia, or South Africa).  They hunt along the pack ice and travel far inland to give birth.   The seals give birth to one pup annually and they can live up to 40 years.

A Crabeater Seal (Lobodon carcinophagus)

A Crabeater Seal (Lobodon carcinophagus)

Crabeater seals can slither over land fairly well and they range farther onto continental Antarctica than any other indigenous mammal.  Crabeater seal carcasses have been found up to 100 kilometers from the coast. So crabeater seals have whole swaths Antarctica to themselves (well aside from big weird penguins, lichens, and Norwegian explorers).   Although they may theoretically eat a crab every now and then, the seals are misnamed.  Their main prey is Antarctic krill, which they eat in huge quantities (as an aside, Antarctic krill is believed to have the greatest biomass of any single species on Earth).  Although they do not have baleen like the great rorquals, crabeater seals have specialized krill-filtering cusps on their teeth which trap the krill and allow water to escape.  When krill are not available, the seals can also feed on fish and squid.

Crabeater Seal Teeth

Crabeater Seal Teeth

Perhaps the most remarkable thing about crabeater seals is their sheer numbers.  Other than humans (and our livestock) they are the most numerous large mammals on the planet.  Caribou and wildebeests exist in herds of hundreds of thousands, but the crabeater seal population numbers in the millions.  The full population of crabeater seals is unknown.  Estimates range from 7 million to 70 million.  Since they are pale colored seals darting between the crushing pack ice of an uninhabited continent we have a population estimate which is off by a factor of ten.  The fact that so few people have seen them might explain why they are still so successful.

A Crabeater Seal enjoys sunbathing on a southern beach.

A Crabeater Seal enjoys sunbathing on a southern beach.

Life around a Cold Seep

This week Ferrebeekeeper has been concentrating on the theme of discovering new life—a search which is very much ongoing even in today’s used-up overpopulated Anthropocene world.  This concept has taken us to the mid levels of the ocean and the mountain jungles of Thailand and Vietnam to encounter species unknown (like this mystery sea slug, the tiny parasitoid wasp, and even a large hoofed mammal). However what is even more shocking is that our world features entire ecosystems rich with life that have only just been discovered.

A photograph of a pool of brine on the bottom of the ocean

A cold seep is an ecosystem on the bottom of the ocean formed around hydrocarbon-rich fluids which seep out of the earth and either “bubble up” or pool at the bottom of the ocean.  The geography of such areas is alien to our perceptions: black pools of asphalt, barite chimneys, and undersea lakes of dense brine (which traps hydrocarbons and sulfites) are surrounded by otherworldly “reefs” of tube worms and benthic mollusks.  The tube worms symbiotically partner with bacteria capable of “feeding” off the hydrocarbons while the mollusks filter feed on the archaeobacteria.   Whole communities of grazers, scavengers, and predators then form around this base.  Such communities are remarkable because they do not rely on photosynthesis as a source of energy and nutrients (much like more famous “black-smoker” ecosystems which are also chemotrophic ecosystems—but which form around hot volcanic vents).  Cold seeps themselves were only discovered in 1983! Now that oceanographers know what to look for, cold seeps are being discovered in locations where we would never have looked for large complicated webs of life.

A Map of the collapsing Larsen Ice Sheet

In 2005, an oceanographic research team studying the seas once covered by the Larsen ice shelf (a melting shelf of ice located off the eastern side of the Antarctic Peninsula) discovered a cold seep community thriving in a glacial trough 850 meters (2,800 feet) beneath the ocean’s surface.  The scientists found great mats of bacteria living on methane.  These bacterial mats were in turn grazed on by strange bivalve mollusks and brittle sea stars.  To quote EOS (a journal of the American Geophysics Union):

These results have implications for the discovery of life in extreme environments, including those found beneath the enormous extent of existing ice shelves and large lakes that lie beneath the Antarctic Ice Sheet. Because of its restricted conditions, the seafloor beneath ice shelves may provide a suitable, widespread habitat for chemotrophic systems; given this, there may be many more such habitats waiting to be discovered beneath existing ice shelves….The seafloor beneath Antarctica’s floatingice shelves covers more than 1.54 million square km [Drewry, 1983], an area of the same order of magnitude as the Amazon basin of Brazil or the Sahara desert.

So science is only just beginning to apprehend the sorts of biomes which are found across huge swaths of Earth.  There are even more remote areas which are wholly unknown—like Lake Vostok, a subglacial lake wholly isolated from the rest of Earth (including the atmosphere) for 15 to 25 million years.  As continental drift and the Antarctic Circumpolar Current froze Antarctica, Lake Vostok was trapped beneath 4,000 m (13,100 ft) of ice, and it has remained so until this year (when an intriguing but sloppy Russian drilling expedition means to pierce the lake).   What scientists discover beneath the other ice dwindling shelves, and what the Russians find beneath the East Antarctic Ice Sheet will have broader implications for how we conceive of life on Earth–and beyond.

A watercolor painting by of chemotrophic life by Karen Jacobsen, an artist who has traveled to the bottom of the ocean via bathysphere to record her impressions!

Antarctica Seen from Space

Imagine standing high above planet Earth and looking down at the blue and white band of seas surrounding Antarctica.  You are looking at one of the most important features of the Earth’s surface.  The turning of the planet and strong westerly winds drive the cold deep waters of the Southern Ocean into the planet’s largest and most powerful current system, the Antarctic Circumpolar Current (ACC).  The clockwise current isolates the frozen continent into its own self-replicating climate. Since there are no great land masses lying in the ring of open water at these latitudes, the ACC also forces waters from the ocean depths up to the surface.  This upwelling brings rich nutrients from the depths and causes immense blooms of phytoplankton (which in turn nurture life throughout all the world-ocean).  Additionally the current stirs the circulation of the Atlantic, Pacific, and Indian Oceans.

The ACC has been known to sailors for centuries.  A sailing ship can travel west along the current with great speed (if the sailors have the bravery and stamina to confront the fierce winds of “the roaring forties”).   The “clipper route” was the fastest sailing route around the world, but it was dangerous.  The three great capes (Cape Horn, the Cape of Good Hope, and Cape Leeuwin) all claimed innumerable lives as did wind, ice, and storm.  Today the clipper route has been abandoned as self-powered ships bring their cargoes of plastic junk straight across the ocean from China (and then cut across the Panama Canal) but sailing enthusiasts still recognize the fastest way to ride the wind around the planet.  The major circumnavigation sailboat races all travel the clipper route.

“Roaring Forties” (Gordon Frickers, oil on canvas)

The true history and significance of the ACC vastly exceeds the paltry recent concerns of navigation and world trade.  Geologists estimate that the ACC current began spinning around 34 million years ago at the end of the Eocene epoch as Antarctica split from Australia and drifted further south.  Back when Antarctica and Australia were still connected, the great amalgamated continent was a place where cold southern water and chill weather mixed together with tropical warmth—thus causing the whole planet to warm up.  However when Antarctica broke away and drifted south, it started a series of climate feedback loops.  The oceans around the continent began to freeze and ice started to build up on the mountains.  An entire continental ecosystem began to change in the cold.  The tropical forests (which had been filled with strange marsupials) began to die and become tundra.  As the Oligocene progressed and Drake’s Passage widened, the rivers–once filled with catfish–turned to ice.  The landmasses of Antarctica became crushed down under immense glaciers.  Antarctica died in the cold.  By 15 million years ago it became as it is now–home to only tardigrades, lichen, and a handful of visiting birds and seals.

The Transantarctic Mountains (photo by John Goodge)

Even now the Antarctic Circumpolar Current still isolates the continent from the warmth of the rest of the world.  Yet through upwelling of iron and other nutrients, the current bolsters an immense fecundity of phytoplankton–the great primary producer of the ocean.  Masses of copepods and krill feed on the algae and the diatoms and they in turn are eaten by fish, mollusks, mammals, birds, filter feeders…everything.  The great southern oceans are among the most diverse and strange habitats for living things.  It is there that the largest mollusk on the planet is found—which is the subject of an upcoming post.

Obdurodon--A Miocene Platypus which flourished 15 to 20 million years ago

Ferrebeekeeper has an abiding interest in monotremes including both the poisonous platypus and the enigmatic echidnas (with their advanced frontal cortex).  But sadly that is about it as far as it goes for the extant egg-laying mammals: there are only two living families of monotremes (with a scanty total of five species split between them).  To learn more about these animals one must turn to paleontology.  Unfortunately even in the fossil record, monotremes are extremely rare.

Based on genetic evidence, biologists believe that the first monotremes made their advent in the history of life about 220 million years ago during the Triassic era; however the earliest known fossil monotreme so far discovered was a fossil jaw from the early Cretacious era about 120 million years ago.  The bones belonged to Steropodon galmani, which seems to have been a beaked swimmer about 50 cm (20 inches) long which lived in Australia.  Steropodon was apparently a giant among Cretacious mammals–most of which seem to have been shrew-sized (so as to better avoid attention from their contemporaries, the dinosaurs). Reconstructions of Steropodon all seem to resemble the platypus, and most paleantologists would probably concede that it was a sort of platypus—as apparently were other Mesozoic fossil monotremes such as  Kollikodon and Teinolophos (platypuses and these platypus-like forbears are called the Ornithorhynchida).  During the Cretaceous era, the land which is now Australia was in the South Polar regions of the world (approximately where Antarctica is today).  Although temperatures were much warmer during the Cretaceous, monotremes must still have been able to deal with terrible cold: it is believed that the extremely efficient temperature control and the deep hibernation mechanism which these animals continue to display first evolved during that time.

An artist's reconstruction of Steropodon

The only monotreme fossil which was not found in Australia was from another platypus-like creature named Monotrematus sudamericanum.  The creature’s remains were found in a Patagonian rock formation from the Paleocene era (the era just after the fall of the dinosaurs). Monotremes probably flourished across South America and Antarctica, as well as on Australia, but evidence is still scarce. There are most likely many interesting monotreme fossils throughout Antarctica, but, for some reason, paleontologists have not yet discovered them. Additionally, unlike the marsupials (which still quietly flourish throughout South America), the poor monotremes were wiped out on that continent.

Another artist's vision of Steropodon galmani--Notice how peeved the poor creature looks!

Last week I wrote about the Eocene era and the great proliferation of mammalian types which took place during that warm and fecund time.  Although most families of mammals alive today first appeared on the scene during the Eocene, obviously the monotremes were already incredibly ancient.  The Eocene does however seem to have been significant time for the monotreme order: the aquatic platypuses were apparently the ancestral monotremes, and echidnas (the Tachyglossidae) probably split off from them during the Eocene.  Unfortunately we have no Eocene monotreme fossils so this conclusion is based on genetic evidence and on the suffusion of Miocene monotremes which include representatives of both Ornithorhynchida and  Tachyglossidae.  Some of these latter creatures are spectacular, like Zaglossus hacketti the giant echidna from the Pleistocene which was about the size of a ram! As Australia dried up so did the monotremes and now there is only one species of platypus left…

The Giant Echidna (Zaglossus hacketti) which lived until 20,000 years ago...

Well, that’s a cursory history of the monotremes based on what we know.  I wish I could tell you more but unfortunately there is no fossil evidence concerning the first half of the order.  Sometimes I like to imagine the first monotremes—which were probably clunky, furry platypus-looking characters with an extra hint of iguana thrown in. These creatures fished in the alien rivers of the Triassic world in a time when dinosaurs and pterosaurs were also still evolving.

Lichen (by WiseAcre)

Cast your imagination back half a billion years ago to the Cambrian geological period.  Although Earth’s oceans were seething with strange experimental life forms, the alien continents were bleak and empty.  Huge brown mountains sloughed away into giant canyons. Black volcanoes eroded into naked black beaches. Great flash floods poured over a landscape bare of plants and animals. No horsetails grew.  No dragonfly buzzed.  Not even a miserable liverwort crouched by the empty streams. But were the ancient continents entirely bare? No—bacterial films and single cell algae were believed to have covered the land, and looming above that primitive slime were the first lichens, symbiotic life forms so hardy that they alone thrive on continental Antarctica today.

Red Lichen living in Antarctica (photo by Gerhard Hüdepohl from Atacamaphoto.com)

Lichen is a bizarre composite organism in which a fungus is paired with a photosynthesizing partner (either green algae or cyanobacteria).  The thallus of lichen (which makes up the organism’s body) is very different from either the fungal or algal components living on their own.  The fungi surround and hold up the algae by sinking tendrils through the algal cell walls (in much the same manner parasitic fungi attack their hosts).  By sharing the resources of the two different partners the organism is capable of surviving extreme desiccation, and, when the lichen is again exposed to moisture, a flood of nutrients becomes available to both partners.

Lichen (from "Art Forms of Nature" E. Haeckel)

The partnership makes for an extraordinarily resilient organism which can be found everywhere on land from the rainforests to the deserts to the highest mountains to the harsh frozen rocks of Antarctica. The European Space agency explored the durability of lichen by blasting living specimens into outer space where, to quote the ESA, the organisms were “exposed to vacuum, wide fluctuations of temperature, the complete spectrum of solar UV light and bombarded with cosmic radiation. During the Foton-M2 mission, which was launched into low-Earth orbit on 31 May 2005, the lichens…(Rhizocarpon geographicum and Xanthoria elegans) were exposed for a total 14.6 days before being returned to Earth….Analysis post flight showed a full rate of survival and an unchanged ability for photosynthesis.”

Lichen dot the face of a Song Dynasty statue on Qingyuan Mountain, China.

Lichens’ strange partnership also creates strange morphological forms. In many circumstances these organisms resemble exotic corals, sponges, or plants. Additionally, many lichens are brightly colored.  The result is often a miniature landscape of bizarre beauty.  I have included some photos from sundry sources but you should check out the lichen photos at Stephen Sharnoff’s site (even disfigured by the trademark, his lichen photos are the best on the net).

Competing Lichens Growing on a Rock

Since it involves both algae and fungi, lichen reproduction can be complicated and takes many different forms depending on the species and the circumstance.  Some lichens form soredia, small groups of algal cells surrounded by fungal filaments which are dispersed as a group by wind. Others produce isidia, elongated outgrowths from the thallus which break away.  During the dry season, certain lichens crumble into dusty flakes which are blown across the landscape.  When the rains come the flakes burst into full growths.  In the most interesting and complicated pattern of reproduction, the fungal portion of the lichen produces spores (as a result of sexual exchange and meiosis) these spores are disseminated across the landscape and then must find compatible algae or cyanobacteria with which to partner.

 

Community Lichens is in the Sawtooth Mountains (photo by Mark Dimmitt)

Lichens are probably long lived and it is possible that somewhere there are those that make the bristlecone pines seem young and have lasted as long as Pando, but who knows?  We have not explored and documented the world’s lichens very completely…or even fully understood the mechanisms of their partnership.  What is certain is that they are one of life’s most efficient colonizers: in areas such as the Atacama Desert and Antarctica, plants cannot grow unless lichen lived there previously (in fact I am going to include this post in my “invaders” category for just this reason). Lichens are also efficient at exchanging carbon dioxide for oxygen, and they are a critical link in the carbon cycle capable of fixing elemental carbon back into the soil and into the ecosystem.  When you look at a tundra landscape and savor the beauty of reindeer, mountains, and arctic birds, spare a thought for the ancient lichen, one of the first organisms on the land and still one of the most important.

Lichen slowly colonize a New England gravestone from the 1700's.

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