Happy Anniversary, Planet Earth! Episode 11: Ocean Deep

On this final installment of Planet Earth we go to the least explored, and vastest space on Earth, the oceans. So without further ado, let’s dive right in (pun intended)!

And because many of these species are found in the new summer movie, Finding Dory, I will attempt to use as many images from this movie as possible.

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We start with the whale shark, which are kind of tricky to evaluate because there is currently no robust estimate of the population size of whale sharks. These gentle giants have a long lifespan and slow maturation rate, which is one of the reasons they are listed as vulnerable. Additionally, the 2010 oil spill in the Gulf of Mexico occurred in prime whale shark feeding area. While it was confirmed that the massive sharks were sighted within the oil  spill, no dead whales were found (do whale sharks sink when dead?).

Competing with the whale shark for tiny delicious fish we have the Yellowfin Tuna. If you are a lover of sushi, or even just a casual liker of sushi, then you like yellowfin tuna. The dark fatty meat makes my mouth water. But this is the problem, as the population is rapidly declining due to overfishing. Big time. They are currently on the “sustainable sushi ” list of multiple different organizations (the fish you should avoid eating if you want your meal to be sustainable).

Speaking of massive filter feeders, we now shift our focus to the vulnerable manta rays. These giants are so evil looking (I mean come on, they practically have horns), it’s surprising that like the whale shark they primarily feed on plankton. They are threatened by overfishing, which is especially problematic given they tend to hang out in waters that are fished… because they like to eat. Capturing and hunting of manta rays is banned in many countries, but commercial fishing continues in others.

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Rounding out our discussion of massive animals that feed on tiny things, we need to spend a minute talking about the blue whale. The largest creature that has ever lived (yes, including dinosaurs, I asked and Sir David Attenborough answered) these graceful giants are endangered. Although not recently (This is supposed to be an update after all) The blue whale suffered from the heyday of whaling which brought the population almost to the brink. Additionally, they have a tendency to run into boats, get caught in fishing nets, and are still occasionally hunted (cough, Japanese, cough). However, the populations have recently seen a rise, which means they may be out of the woods! Assuming their food supply, krill, isn’t killed off too quickly due to global warming.

The septapus (an octopus who lost a set of arms) from Finding Dory.

The septapus (an octopus who lost a set of arms) from Finding Dory.

We know that corals around the world are dying (and if you don’t know, read about it here). Soft corals are not an exception to this rule, and since the airing of Planet Earth they have been dying. While our corals and many other species are declining, I recently posted the opposite trend, that cephlapods are in fact INCREASING. This include the adorable dumbo octopus we see, as well as the nautilus. And the septapus we know from Finding Dory.

The dumbo octopus, both real life and Pixar style

The dumbo octopus, both real life and Pixar style.

Finally, our knowledge and understanding of the life around ocean vents has catapulted forward, mostly due to the sequencing of every microbiome that has ever existed. And we love sequencing around ocean vents because the most basal of lifeforms, extremophiles, or archae bacteria, are found near ocean vents. In addition, they are promising for a number of initiatives including their propensity to eat things that we want to get rid of (read about it here).

Thank you for joining us as we revisit the Planet Earth series!

Happy anniversary, Planet Earth! Episode 10: Seasonal forests

The tenth episode of Planet Earth brings us to the biological communities I think of as “home” — seasonal forests. I grew up in rural Pennsylvania, with second-growth deciduous woodland literally in my back yard, went to college within sight of the Appalachian Mountains, and spent my first “real” job in field ecology surveying understory plant diversity northeast of Pittsburgh. Today, I’m working on the other side of the continent, but now studying some of the most widespread tree species in forests from the Pacific Northwest to the Yukon taiga. I could almost illustrate this entire recap with images from my personal Flickr stream.

(Flickr: JBYoder)

Old-growth conifer forest (lots of Douglas fir, Pseudotsuga menziesii) around the Coquitlam Lake reservoir in British Columbia (Flickr: JBYoder)

I’ll try to resist the temptation.

We start at what is, arguably, the most seasonal of forests, taiga, where the growing season may last just a month. These snow-covered woods seems marginal, but boreal forests account for one third of the trees on the planet, Sir David Attenborough tells us. The newest comprehensive assessment of tree density worldwide, published last year, found that a median hectare of boreal forest has as many, or slightly more, trees than an average hectare of tropical forest — but it also puts the boreal share of the global tree count at closer to one quarter of all trees, and finds that “tropical moist forest” accounts for a slightly larger share.

Figure 1 from Crowther et al. (2015).

Figure 1 from Crowther et al. (2015).

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Happy Anniversary, Planet Earth! Episode 9: Shallow Seas

The 9th installment of the series, “Shallow Seas” opens with the statistic that 8% of world’s ocean volume contains a majority of its marine life.

I’m in the middle of reading Hope Jahren’s “Lab Girl right now (a fantastic, inspiring book about her life as a scientist that I highly recommend). In the opening paragraph of the Prologue, she mentions a reason why she is not interested in studying the ocean: there is six hundred times more life on land than there is in the ocean. This is true! I don’t think I’ve ever read someone’s reason for not being interested in studying the ocean, having studied and worked for marine-focused institutions for the past 10 years while also living in beach and island cultures with students clamoring to be marine biologists. While Dr. Jahren’s point has more to do with her own interests in land plants, in the broader sense I agree that there is much to be studied and managed on land because terrestrial ecosystems have indeed produced more life than in the ocean. As a result, activities on land have the ability to negatively affect the diverse ecosystems of the “shallow seas”.

Over half of the world’s human population lives within 60 km of a coastline. These are remarkable ecosystem areas surrounding coastlines, separating the land from the ocean.

I lived on Yap Island in the Federated States of Micronesia as a Peace Corps Volunteer from 2004-2006, working with counterparts at the Yap State Environmental Protection Agency. I learned so much from my hard-working colleagues, far more than they probably gleaned from me.

(Left to right, top to bottom) Me (2006), view returning to the MicroSpirit ship with coconuts from an outer island (2004), traditional Yapese dance (2005), lunch on the boat (2004).

DSCN4257 coconuts DSCN3853Elato Ship Wrec

Small island nations are deeply connected to their environmental resources, in both cultural and economic senses. Future climate change and accompanying sea level rise is affecting island societies more than other societies. The President of Palau has spoken prolifically on this topic, and was at the International Coral Reef Society meeting in Palau last month (June 2016).

Regina and Larry Raigetal, of Waa’gey.org recognize this in their efforts to confront challenges: “Extreme isolation, limited economic opportunity and climate change are big problems for the small atolls of Micronesia’s outer islands.” Waa’gey focuses on fostering pride in traditional culture, which has worked to sustain the population in the past, including traditional sailing navigation. Small island nations like Micronesia have populations less then a fraction of some developed countries, yet live entirely in coastal areas.

On the mainland of the U.S., Florida has over 1,000 miles of coastline and is becoming more and more affected by land-based activities. Beginning in the 1900s, land use changes were abundant in the state of FL. Miami was built out by developers and the sugar cane industry moved into the Everglades, a natural wetland area. Originally, water from Lake Okeechobee at the center of the state would naturally drain through wetland areas in south Florida eventually reaching the Gulf. Today, the Army Corps of Engineers has diverted the water out through a series of canals to the east and west, with significant freshwater discharge into estuarine areas and onto sensitive coral reefs causing an ecological disaster.

Economic benefits of the Indian River Lagoon resources were valued at more than $3.7 billion in 2007.

There is a lesson that Floridians and coastal US citizens can learn from the efforts of Waa’gey and other small coastal nations. (Teamwork in Ulithi atoll, outer islands of Yap):


We can team together to place renewed value on practices that were common before development. This means supporting efforts to restore water flow in wetland ecosystems back to their original state. Buying undeveloped land to prevent further land use changes and damage. Lawmakers should encourage sustainable lifestyles by requiring homeowners near and on coastal areas to preserve and restore their shoreline vegetation, slow development and not use fertilizers. Provide more sustainable funding to long-term scientific studies, such as those in Dr. Joshua Voss’ lab at Harbor Branch Oceanographic Institute at Florida Atlantic University, investigating the effects of discharge on near-shore coral reefs.

A well-balanced ecosystem brings long-term benefits. 

The Planet Earth episode ends by focusing on the charismatic macrofauna that depend on the shallow seas: the octopus mimics a moving/rolling rock, a gurnard fish with pectoral fins camouflaging its shape, a jawfish hides underground. Plants manage to take root, which are then pruned by sea turtles. Marine mammals such as dugongs and manatees are the largest herbivores in sea, eating nothing but fleshy rhizomes of sea grass. Dolphins discover a shoal of bait and are shown surfing, riding a wave. Fish refuge close to shore water only few cm deep. Sea birds, cormorants. Shallow temperate seas contain greatest concentration of fish on planet. Huge shoals migrate to feed in rich waters. Cruising back and forth between equator and poles, humpback whales – among the largest inhabitants of the ocean – are shown migrating between the shallow seas where life proliferates so abundantly on our planet.

Sunset in Micronesia:


Happy Anniversary, Planet Earth! Episode 8: Jungles

On this installment of Planet Earth we dive into the depth of Jungles, which really means we stroll down past the canopy, the upper forest, all the way down to the floor of the jungle to see the creatures that thrive where light barely reaches.

The biggest update since Planet Earth aired 10 years ago, is the general deforestation and specific poaching of jungle trees. While most articles focus on the amazon (which wasn’t the specific focus of this episode), it can generally be applied to other jungles as well. And importantly for all the animals mentioned in this episode, the deforestation of the jungles affects their habitats. David Attenborough tells us that fig is the #1 fruiting tree that is used to sustain life. However, even figs are specifically being targeted, which puts the vast numbers of vertebrates (from Howler monkeys to birds) in jeopardy.

Now the frogs are a kind of confusing update, because there are competing factors that are threatening amphibian populations worldwide. First and foremost we need to talk about pathogens (love me some parasites…), specifically the chytrid fungus. This devastating pathogen can cause up to 100% mortality in some amphibian populations. However, there is some evidence that chytrid is being amplified by climate change, which is resulting in the perfect temperatures for the spores to proliferate. Finally, habitat degradation, and warming climatesare causing problems for frog species independent of chytrid , especially those specialized to the specific habitat of the jungle. So as adorable as our little frog friends were, sneaking into their mating practices, we may not be seeing them around for much longer.

While only talked about for a moment, slime molds may be WAY cooler than they even looked in this episode. Check out the cool new research.

Slime molds are actually cooler than even this episode made them look.

Slime molds are actually cooler than even this episode made them look.

Additionally, beetles were only mentioned briefly, but are worth mentioning here. J.B.S. Haldane was asked what he knew of the creator based on his studies of biology and famously noted that “The Creator, if He exists, has an inordinate fondness for beetles”, due to their abundance world wide (in terms of number of species the beetle CANNOT be beat). However, it turns out that beetle populations worldwide are declining. While the reasons for this vary (see above under “reasons frogs are declining”), and is not consistent across all beetle populations (see “most number of species worldwide”) it is a general pattern worth noting.

"An inordinate fondness of beetles"

“An inordinate fondness of beetles”

As someone who teaches parasitology let me tell you a little fact. People love “zombie” parasites. Every year I teach students about Captain Higgins, which is not a spore (like the awesome fungi talked about in the Jungle episode) but a flatworm that manipulates its host to further it’s own lifecycle. It even uses ants! Read about it over at the Oatmeal Comic.

From the Oatmeal comic about the flatworm "zombie" parasite Captain Higgins.

From the Oatmeal comic about the flatworm “zombie” parasite Captain Higgins.

Finally the flying lemur, which has been trucking along. Because of the phylogenetic and morphological uniqueness of this species, it is under constant surveillance for better conservation efforts. Because of their limited dispersal abilities, deforestation is especially threatening to the lemurs (not really lemurs, but we’ll call them that for simplicity). Additionally, they are hunted, in different areas for varying reasons. In some places their consumed as a delicacy, in others they are hunted for hats. However, in Samar they are killed because the local culture thinks they are evil. So… that happened.

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Flying lemurs look like this in real life.

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And like this in the television series “The Avatar: The Last Airbender”. I can’t honestly say which of the two phenotypes looks more realistic…

Overall, things in the jungle are largely changing because of how we are moving in on their territory. Stay tuned for “Shallow Seas” up next.





Happy Anniversary, Planet Earth! Episode 7: Great Plains

The seventh episode of Planet Earth takes us out into wide-open spaces: the grasslands of Asia, the Americas, and Africa.


(Flickr: Dan Zen)

Grasslands are defined by a plant community particularly prone to “plant blindness” — it’s easy to see grass as stage-dressing for the dramatic animal life found on the Great Plains, the tundra, or the Tibetan Plateau. But Planet Earth gives grasses their due: “Flooded, burnt, baked, and frozen — grass can withstand it all,” says Sir David Attenborough. The Poaceae is a big, diverse family of plants that grow in some of the harshest conditions on the planet.

Multiple grass lineages independently evolved a new, more efficient form of photosynthesis. As Earth shifted to a cooler and drier climate, with lower atmospheric concentrations of carbon dioxide, starting about 40 million years ago, that may have helped grasslands spread into regions where rainfall and temperature weren’t suitable for forests — and now they cover more than a quarter of the planet’s surface. Some of those grasslands support the biggest assemblages of birds and mammals on the planet, as we see in this episode, which takes full advantage of the openness of its focal community, giving us lots of aerial photography tracking the movements of thousands of caribou, bison, or snow geese.

Most of us in North America know snow geese as winter migrants to lower latitudes, but here we see them on their Arctic breeding ground, establishing and protecting nesting sites — first from other pairs of nesting geese, then from Arctic foxes. Planet Earth frequently follows the nature documentary tactic of employing predator-prey struggles for drama, but the one between the Arctic fox and the snow geese has some twists on the standard script. First, we see the fox trying to gather up so many goslings that she can barely fit them all in her mouth, and we get to cheer as her greed gives the geese time to catch up and run her off. But then we see what she does with the single, sad gosling that doesn’t get away — she brings it to her own clutch of adorable fluffy pups.

Kids! I brought dinner. It's gosling.

Kids! I brought dinner. It’s your favorite — gosling.

Planet Earth is at its best when one adorable fluffy animal is feasting on the flesh of another adorable fluffy animal.

The fox-goose drama is, to my mind, the most interesting predator-prey chase in an episode with a lot of them, most featuring cool camerawork. An aerial camera tracks wolves working together to separate a caribou calf from an immense herd; night-vision footage captures lions taking down an elephant. And on the Tibetan plateau, where pikas keep watchful eyes out for The World’s Most Nonplussed Fox.


Ugh, documentary filmmakers again?

The Tibetan Sand Fox has great pika-stalking moves, but its thick fur squares off its head in a way that makes it look bored, even with a mouthful of pika. Edited into this hunting sequence are shots of watchful pikas, which give the impression that they’re reacting to the fox’s eventual capture of their neighbor.


Oh, god, Bob! He got Bob!

Relatively few of the species we see in this episode are formally recognized as endangered: snow geese, caribou, gray wolves, Arctic foxes, pikas, Tibetan sand foxes, and even most African baboon species are all currently listed as “least concern” by the IUCN. American bison are near-threatened thanks to conservation efforts and semi-domestication — after extensive hunting in the 19th century, there were once as few as 541 in all of North America. Both species of African elephant (the bush elephant and the forest elephant) and lions are listed as Vulnerable, and their numbers are not on the upswing.

The widespread nature of grassland habitats has, perhaps, shielded all these species from the impacts of human activity — though none of them are as numerous, or as widespread, as they once were. And of course they’re all experiencing a human impact that no habitat on Earth can escape: climate change. From the cues governing the migrations of snow geese and caribou to the rainfall that restores the green to the African savannah, the annual cycles of weather that shape life on the grasslands are no longer as certain as they once were. Grasslands arose over a long period of global change, and they may be more resilient to the much faster changes we’ve created than other ecosystems will be — but the great grasslands shown in this episode Planet Earth may look very different in another few decades.

Be sure to stick with us as we continue our celebration of Planet Earth’s 10-year anniversary! Check out our posts on “From Pole to Pole,” “Mountains,” “Fresh Water,” “Caves,” and “Ice Worlds.” Next week, we move off the sunny plains and into the jungle.

Happy Anniversary, Planet Earth! Episode 5: “Deserts”

As the fifth episode of Planet Earth begins, it feels like you might have stepped onto another planet.

The Namib desert (flickr: mariusz kluzniak)

The Namib desert (flickr: mariusz kluzniak)

Desert landscapes have an alien, otherworldly feel to them; vast swaths of sand around the world have acted as the backdrop for NASA equipment tests, science fiction classics like 2001: A Space Odyssey, and, of course, supposed extraterrestrial activity. But despite their interstellar associations, deserts are very much of this planet. As narrator David Attenborough tells us, deserts cover a third of the Earth’s surface, and all of them are populated with life.

“Deserts” takes us into a world of extremes, where the environment can go from habitable to hostile in an instant. In this 10-year anniversary post we will relive the episode’s most intense moments, highlighting the incredible challenges that accompany life in Earth’s driest places. We will also take a look at the unique difficulties conservationists face in attempting to protect the organisms that inhabit these inhospitable regions.

Desert Survival is About Timing

In the deserts of our planet, extremes are the norm. Attenborough tells us that temperatures fluctuate annually in the Gobi Desert from -40° C in the winter to 50° C in the summer. Death Valley holds the record for highest temperature ever recorded, at 56.7° C. In the Sahara Desert, sandstorms to rival Mad Max can reduce visibility over regions the size of Great Britain for several days, and the resulting dust clouds can affect weather patterns around the world.

Things don’t happen in moderation here.

Good conditions are transient, and when they do occur, organisms must be ready to take full advantage of them. Timing is everything when you are trying to survive in the desert, a fact that is apparent in multiple segments of the “Deserts” episode. Kangaroos in Australia forage in the early morning when temperatures are moderate, but must find a tree that provides suitable shade from the sun before midday, lest they risk overheating. Scorpions and toads in the Sahara have almost no tolerance for the sun’s rays, and must emerge from shelter only at night.

The importance of timing shows up in somewhat unexpected ways as well. For example, wild camels have fine-tuned the timing of their breeding season to coincide with the onset of winter, when precipitation is the most abundant. In the Gobi Desert, snow covers the ground throughout the winter months, providing a reliable and widespread source of water for the camels. Planet Earth camera crews searched the Gobi for two months for these rare and elusive animals, finally obtaining fantastic footage of the bizarre mating rituals of the species.

The ephemeral nature of favorable conditions means that a single bout of resource availability must sustain desert plants and animals for long periods of time. In Namibia, a flash flood (one of just a handful that occur annually) produces a burst of vegetation growth. This rare resource attracts oryx to area, which in turn attract a family of lions. Attenborough tells us that a single oryx will sustain the entire lion family for a week. These infrequent bouts of productivity are key in maintaining life here, for a range of species.

Rain is also infrequent in the Sonoran Desert. Consequently, the saguaro cactus is well-adapted to make the most of the brief Arizona monsoon season. The pleats on its trunk allow the cactus to expand, so that it can absorb as much of this valuable resource as possible- up to 5 tons! And if the cactus is good at collecting water, it’s even better at making it last; it can live off these stores through multiple months of drought.

A saguaro cactus (flickr: Michael Wilson)

A saguaro cactus (flickr: Michael Wilson)

When resources like water are so difficult to come by, one survival strategy utilized by many desert species is to rely on other organisms collect them first. In the Atacama, the only predictable source of water comes in the form of a fog generated by cold ocean currents. Coastal communities of plants called lomas collect the fog’s moisture, and provide life-sustaining hydration for a number of desert organisms. Guanacos eat cactus flowers for the water they contain, and coyotes lick dew off of moisture-loving lichens.

Interacting with other species can also be key if you are a traveler, trying to get across the depauperate desert environment as quickly as possible. For just four weeks during the summer, saguaro cacti bloom during the night. The timing of this event corresponds to the annual migration of the lesser long nosed bat. As bats travel across the Sonoran during their trip from Mexico to the United States, they subsist on nectar from the flowers, fertilizing the next generation of cacti along the way. The bats would have no hope of making it across if it wasn’t for this short-lived food source, and the saguaros in turn rely the bats for pollination.

While resources are fleeting in the desert, we learn that some elements of this ecosystem stick around for a surprisingly long time. For instance, star dunes in Namibia can reach up to 300 meters high. The sand at the peaks of these dunes is in almost constant motion thanks to the wind, but sand at the base may not have shifted for 5,000 years. In addition, locust eggs lie dormant for 20 years before they hatch, and seeds in Death Valley can wait for 30 years for favorable conditions before they sprout. A “superbloom” of wildflowers is currently taking place in Death Valley- what a fantastic way to celebrate the anniversary of Planet Earth!

The Curious World of Desert Conservation

In the desert ecosystem, organisms face a somewhat bizarre set of conservation challenges.

From the illicit underground cactus trade, to the legacy of nuclear weapons testing; from rabbits run amok in Australia, to the controversially brutal hemorrhagic disease released to control them; from a history of violent confrontations between the federal government and armed ranchers, to the endangered desert tortoise that first set those land disputes in motion- conservation in the desert has a strange and dramatic past.

In terms of scale, The Great Green Wall of Africa is as dramatic as conservation comes. An effort to counteract the ongoing effects of desertification, the Great Green Wall project proposes to plant a corridor of drought resistant trees along the southern edge of the Sahara. The Great Green Wall, if completed, will be really, really long: 4,750 mile long and 9 miles wide, to be exact. It’s a huge undertaking, with 12 nations currently in collaboration on the project. But if all goes to plan, the Great Green Wall will be quite an amazing feat of conservation.

Big game hunting presents another dramatic desert conservation issue. In 2014, Namibia issued a handful of licenses to hunt desert elephants. Desert elephants are distinct from African elephants, exhibiting a number of behavioral and morphological adaptations for desert life. These locally adapted animals are also exceedingly rare, with fewer than 100 individuals in Namibia. However, desert and African elephants are not technically considered separate species, and thus the Namibian government does not currently extend any additional protection to these populations. This controversy highlights the importance of species delimitation in conservation- an issue that is only more dramatic in the context of big game hunting.

A desert elephant (flickr: Vernon Swanepoel)

A desert elephant (flickr: Vernon Swanepoel)

The plants and animals of the desert are some of the planet’s most hardy, but even they can have difficulty rebounding from disturbance. In the Atacama, the life-sustaining lomas are at risk. Local people rely on the water-collecting capabilities of these plants for survival, but have also destroyed the majority of the vegetation to make way for agriculture. Researchers are attempting to replant one particular plant, called the tara tree, in hopes that it will help to rehabilitate these important communities. But new seedlings seem to have trouble taking hold within existing lomas. Lomas are home to 1,400 plant species, around half of which are endemic; their loss would be truly devastating to the region.

Deserts, with their reputation as barren wastelands, may not seem like obvious targets of conservation. Desert flora and fauna face extreme conditions on an everyday basis, and the added strain of human impacts makes survival all the more difficult for these organisms. But on the bright side, evidence suggests that our effects on deserts can be successfully mitigated. In the case of the once-threatened Eureka dune grass, limiting the use of off-road vehicles in particular regions of Death Valley has been enough to allow populations of the plant to reestablish.

Life in this unique desert ecosystem defies all odds, and protective measures will be key for helping it to persist into the future.

Be sure to stick with us as we continue our celebration of Planet Earth’s 10-year anniversary! Check out our posts on “From Pole to Pole,” “Mountains,” “Fresh Water,” and “Caves.” Next week we’ll be looking at the polar opposite of deserts: ice worlds!


Happy Anniversary Planet Earth pt 3: “Fresh Water”

All live on land is dependent on Fresh water, but it is only 3% of all water available on earth, as David Attenborough reminds us in the opening lines of the third episode of Planet Earth.


Unlike some of the other Planet Earth episodes, this one is clearly a journey. We follow fresh water from where it condenses at the top of mountains, down to where it eventually meets oceans, with a slight detour to talk about some epic lakes on the way.

We start in the mountains of Venezulua, the epic Mountain plateaus that inspired Arthor Conan Doyle’s Lost World. At these heights, it rains a ton. The ocean air gets pushed up to great heights, the air condenses and falls as rain by the gallons. We’re talking about a tropical down pour every day of the year.

From there it cascades down, “from humble streams to mighty rivers”, until we get a view of Angel falls (the inspiration for Paradise Falls in the Pixar movie Up).


Where only the strong thrive

After landing on the ground, we move into my favorite part of the episode, embracing the uncharismatic minifauna. The fresh water is full of energy, and low in nutrient making life difficult. And yet somehow invertebrates thrive, clinging on to the rocks for dear life. Hellgrammites, with their busy gills to extract oxygen and Bamboo shrimp filter out particles as they rush by using their fanlike forearms. And although they may not be small, no one can say that the Giant Salamander is charismatic. With a face only a mother could love, they can grow up to 2 meters long and are one of the only predators in these rough waters. With poor eyesight, they more than make up for it using the sensory nodes on their face and body.

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Damn dam building

Similar to salmon, the giant salamanders swim upstream to spawn. Their migrations is increasingly being blocked by dam-building. Ramps and staircases are being added to allow them to move upstream, but the impediment has effected the population. To see one possible solution, I would like to draw your attention to the salmon cannon:

I give you, the salmon cannon.

I give you, the salmon cannon.

Water: The epic battle for life

Next we enter the segment of this episode that I’d like to call “Ichthys/Herps vs. Mammal”. We have ahead of us a series of monumental battles between predator and prey that take place in or near fresh water.

We begin with salmon, known to travel hundreds of miles back to their spawning grounds to reproduce (see above note about the salmon cannon facilitating this migration). But, low and behold, where there are happy breeding salmon, there are also hungry bears ready to eat them. In this episode we get almost face to face with a grizzly bear, swimming along looking for that oh so delicious tasty morsel. And what’s more, he’s brought along two adorable cubs to teach to hunt. And maybe share his food.


As we leave the mountains, the fresh water warms and begins to support more life. In comes the world’s most social otter in India. They rub coats, fish together, and ward off predators together. First, we see the otters diving gracefully to catch, and teaching their young otters to fish as well. The social otters are together able to defend themselves against a 4 m long crocodile.  While at first the otters seem hopelessly outmatched (and if they were alone, they most likely would be) but as a group they successfully put him in his place.

Finally our river starts to meander slowly across the planes of east Africa. No longer as dynamic and destructive, but the life source for millions of wildebeests. Where the wildebeest go to drink the crucially important water, the Nile crocodiles (5 m long?!) feast on the abundance. While these two creatures are seemingly well matching in size and ability, these massive crocodiles are shown to repeatedly catch and devour their prey.

Stay away from the humans and you’ll be fine

The freshwater, social and crocodile destroying otters seen in this episode are facing threats from construction of large-scale hydroelectic projects (see above problem with damn dams). With humans over fishing their prey, polluting the water, and poaching their soft fur, these otters have seen serious population decline, and are listed as endangered.

The biggest problem Nile crocodiles face? They have a tendency to attack and eat humans, who in turn try to shoot the massive apex predator. They are responsible for hundreds of deaths each year, which ultimately gets them shot. Despite this, the population size is not threatened. More threatened than crocodiles, are wildebeests. Their massive migrations require open land. A fence was erected between the wildebeest and their watering hole by the Botswanan authorities, and it killed thousands of wildebeests reducing the herd by 90%.


Detour: Check out these lakes!

While most rivers run to the sea, some drain into lakes. Because in general the Planet Earth series tends to focus on the extremes (largest mountains, smallest insect, etc), we start by visiting some of the largest lakes, and then work our way up to the biggest. The first three are in Africa, and Lake Malawi, Lake Tanganyika and Lake Victoria. The fish life in these lakes contain insane amounts of biodiversity. There  are 850 different cichlids alone, all evolved from one ancestral species (adaptive radiations anyone?). The males make craters to impress females, while others brood their young in their mouths for predators.


Next we drop to the bottom of Lake Malawi, only to race back to the top. The floor is 700 m deep, where in the anoxic water allow the lake fly midges to hide from predators. They then rise to the surface for the most epic looking mating ritual I have ever seen invertebrates do. The density of flies are so intense they look like columns of smoke, instead of columns of flies mating. As the smoke clears, the flies fall to the lake surface, and die.

The worlds largest lake, or next stop, is a lake the has everything. Seriously if you want to study any biological question, study Lake Baikal. It contains a forest of sponges, the worlds only freshwater seal, and goofy looking crustaceans.


Endemic Fish are the Most at Risk

Of the 850 species of cichlid, 184 are vunerable, 52 are endangered and 106 are critically endangered. Additionally, many are thought to be extinct. This is largely due to the introduction of the Nile perch in Lake Victoria, which decimated a lot of cichlid populations.

The biggest threat to the vast diversity of life in Lake Baikal is pollutants. A pulp and paper mill plant was constructed in 1966 directly on the shoreline. It was successfully shut down in 2008 (YAY!) but reopened in 2010 (BOO!). Luckily, it continued to be unprofitable and closed for good in 2013. It has now been turned into an nature reserve.

The Biggest of Big Rivers

Back on track heading toward the ocean, we start talking about the worlds most epic river, the Amazon. There are more fish species described within this massive river than in the Atlantic Ocean. The boto dolphins drive many different species of fish before them in a a wave of death. To attract the females, male dolphins carry large objects in their mouths, such as branches, or rocks.


In the flat flood planes of the Amazon the river annually overflows its river and generates the worlds largest wetland. Remember those stories about pirañas in your childhood? They are more scary in person as we find out in our next segment. Ready to pick off any fish, a feeding frenzy develops in seconds, stripping a fish to the bone in minutes.

The Amazon in Trouble

While the pirañas and boto dolphin populations are not listed as endangered (although the dolphin has flirted with that title before), the amazon river faces various threats from dams (I’m seeing a pattern here…), mining, overfishing, and deforestation sending various pollutants into the river.

Want more updates/celebrations of this fantastic series? Check out the previous posts (From Pole to Pole and Mountains) and come back next week as we head down into Caves.