Archive for the ‘The 6th Mass Extinction’ Category

Angels of Death

Wednesday, December 15th, 2010

Hi Folks,

Here are a couple of great links pirated from the Deep Sea News blog.

The subject of that blog’s discussion is what the author calls “sea angels,” rather beautiful predatory swimming snails in the genus Clione.   Embedded below is a movie of one swimming lifted from YouTube.   These pretty liddle snails were called “sea butterflies” in the Pacific NW – off the British Columbia and Washington coasts, where I had many chances to observe them, both during and after my graduate studies.

In that area, the common species reaches lengths of about 2 cm – 3cm, roughly an inch or so, but most of the individuals I have seen have been smaller.   These are shell-less snails, found in the water of the colder oceans through out the world.  They swim all their lives.

“Sea angels” and “sea butterflies” ….. ah…. such cute names…

Sorta like calling a hunting tiger, “Fluffy,” or a semi-starved, very hungry, fresh-from-hibernation-and-in-a-(REALLY)-bad-mood Grizzly bear, “Snuggles.”  

Individuals in Clione species snails are specialized predators that appear obligately bound to eat only another pelagic swimming snail.  At least that is the reading from the snail biology gospel; in reality I don’t think they have been studied well enough to know if they have any alternative prey.   While Clione individuals lack shells, their prey do have shells and look rather like a regular snail; both species have large extensions of their foot which they flap like wings.  This gives all of these snails the group name of Pteropods, or “wing-foot,” snails. 

I have embeded another movie, this one showing Clione individuals attacking and eating their prey, Limacina.  And as you watch the movie, I think you will see why I consider the name of Sea Angel to be a bit…. inappropriate.  Unless, that is, it is modified to be the “Sea Angel of Death.”

Swimmers near bathing beaches should be thankful that Clione individuals don’t reach about 2 m long (6.6 ft) and have a taste for humans.

A few times when I was teaching a course about Marine Invertebrates at a university field station/marine laboratory on Vancouver Island, I was lucky enough to be able to have had my theaching assistants collect some individuals both Clione and Limacina within a day or two of one another.   For the class, I would take a large graduated cylinder – these are about 3 feet long and several inches in diameter.  And then I would put in one or two Clione individuals and let them become acclimated, typically that only took a minute or two.  Then I would have the students gather around, and would introduce two or three Limacina.   The rapidity and apparent “ferociousness” (this is a anthropomorphic adjective, but after watching the Clione at work, it seemed to fit, but probably a better adjective is “efficiency”) of the attack would typically leave the students, quite literally, speechless.

Most of the time marine biologists (and I suppose other folks who see such things) typically regard snail predation as a slow and rather leisurely process (albeit animals like Cone snails will also demonstrate the other extreme).  After all, an oyster drill (a muricid whelk) drilling a hole through a bivalve shell is hardly action that is exciting, except, perhaps, to the participants.  

Then, if you are very lucky, you get to see something like Clione attacking a Limacina.  Wow!!!  It kinda blows away the stereotypes and misconceptions…

If you think about this system, wherein one pelagic snail lives by preying only on another pelagic snail, a bit further, I think it is really cause for wonder.  At best, Clione – the predators – are found in aggregations (I really don’t think one could call them “schools,” or “herds” or “flocks”) or patches maybe several meters in volume, and with a few snails per cubic meter.  More often the patches arel larger a few hundred meters on a side, and the density is one or two snails per 5 or 10 cubic meters.

So… lots of water… not many predators….just swimmin’ along being their little sea angelic selves, and with a LOT of water between them.  

Now… the prey – and the same sort of situation.  Lots of water, not many prey.

Two diffuse patches of animals in a very large body of water, what are the odds that any one snail of either species will encounter an individual of the other species?

Well, the odds have to be pretty good or the animals wouldn’t be here!  But still, it is not like these are pedestrians on the sidewalk along a busy street bumping into one another. 

I don’t know of any research that has been done investigating these interactions ecologically in nature.  I suspect the logistics of such research would make it prohibitively expensive (lots of ship time, for example), but the questions raised by the necessity of such interactions are really pretty interesting, I think you will agree.

Perhaps they are being studied at the present.  The author of Deep Sea News blog mentions a student/researcher/photographer, Natalia Chervyakova of Moscow University, who has taken some images of Clione feeding in nature – an amazingly difficult proposition.  Here are some of her images from the White Sea.  These are some of the most spectacular underwater macro photographic images I have ever seen.   And having taken thousands of underwater shots, including a number of planktonic macro shots, I can attest to the skill and effort involved and demonstrated by these images.  I would have killed to have been able to get one – 1 – image like these.  I would have killed a lot more, to have had the skill to be able to do it repeatedly.

Finally, shelled pteropods, similar to Limacina in some regards, are at the base of the zooplankton food chain throughout much of the world’s ocean.  They are especially abundant in the very rich fishery regions of the cold temperate and boreal seas, where they eat phytoplankton and convert it into their tissue. In turn they are eaten by many other organisms.  Two or three times removed, they are the fish flesh or krill that is harvested for human consumption or use, to say nothing of the top predators in those ecosystems, whose trophic position has been usurped by humans.   These pteropods have aragonitic shells, and as the oceans acidify they will be amongst the first to be affected by this interesting tiny experiment in the alteration of the ocean’s physical parameters.  “Affected” … A nice polite word for “Exterminated” by both human action (the addition of massive amounts of excessive carbon dioxide to the atmosphere) and inaction (no attempt to slow down those additions).

The sheer and utter stupidity of the human species, both individually and collectively is truly mind-boggling.  Here we are, well on our way into the sixth major mass extinction event in the Earth’s existence, and politicians play games of posturing over public images and the majority of the public wastes its time paying attention to the foibles of ephemeral pseudo-entertainer or some ridiculous sporting event.  I guess over the symbolic grave of humanity, our epitaph should be, “Considering their potential and abilities, they had their priorities straight.”

Until later,


Ah, The Good News Just Keeps On Coming…

Thursday, December 9th, 2010

Today’s reading material is by J. E. N. Veron, courtesy of a link in the Yale 360 blog, “Is the end in sight for the world’s coral reefs?”

Of course, the aswer to the question posed in the title to this essay is obvious and is rather succinctly stated by Veron as well:

“It is a difficult idea to fathom. But the science is clear: Unless we change the way we live, the Earth’s coral reefs will be utterly destroyed within our children’s lifetimes.”

Now… for a show of hands… Is there anybody out there that thinks we will change the way we live, 1) at all, or 2) in time to save coral reefs from going the way of the non-avian dinosaurs? 

Hey, its not all bad, we could start a betting pool as to the year or month when the scientists of that future time could declare that the last coral reef finally wasn’t one anymore!

Any regular (if there are any – I really am sorry about the aperiodic nature of the blog, the explantion of that would take too long to write and really isn’t important – but I do hope to do better in the very near future) readers of this impossibly unperiodic electronic space in the aether, have surely noticed my lack of optimism as well.  I think many of scientists who voice public optimism are privately much more “pragmatic” than their public utterances seem to imply and in some – few – cases I have heard about, almost suicidal from the depression and grief of being in the position of observing and documenting this aspect of what is now becoming known in the paleontological community as “The 6th Extinction.”  — The name derives from an examination of the fossil record, wherein there are 5 major extinction events that punctuate the history of life.  On the plus side, so far… life has always recovered and rediversified after these extinction events.  On the negative side, once the cause of the event has been removed, that recovery has always taken tens of millions of years.  Evolution is sure and certain – but to refill a lot of “vacant ecological niches” takes a lot of time.

The positive take is that the changes that occur over the next few decades that will happen should be “interesting.”

And young people today will get to see another interesting phenomenon, where 30 or 40 years from now, new students of marine biology will see this changed (and to my – by then-  long dead eyes) and depauperate, truly ghastly, world as “normal,” the status quo; rather like tourists who now go diving for the first time on (the pathetic algal covered ruins of) what used to be the coral reef at Cozumel or other Caribbean vacation spots, and think they are seeing a thriving coral reef. 

This is what Jeremy Jackson, now one of the “grand old researchers” of the Caribbean coral reefs refered to, in 1997, as “sliding baselines.”  (The underlined emphasis is mine, to emphasize that this has happened to me, too).   

J. B. C. Jackson (1997) Reefs since Columbus. Coral Reefs 16, Suppl.: S23-S32:

 “The problem is that everyone, scientists included, believes that the way things were when they first saw them is natural. However, modern reef ecology only began in the Caribbean, for example, in the late 1950s when enormous changes in coral reef ecosystems had already occurred. The same problem now extends on an even greater scale to the SCUBA diving public, with a whole new generation of sport divers who have never seen a “healthy” reef, even by the standards of the 1960s. Thus there is no public perception of the magnitude of our loss.

 Another insidious consequence of this “shifting baseline syndrome” is a growing ecomanagement culture that accepts the status quo, and fiddles with it under the mantle of experimental design and statistical rigor, without any clear frame of reference of what it is they are trying to manage or conserve.  These are the coral reef equivalents of European “hedgerow ecologists” arguing about the maintenance of diversity in the remnant tangle between fields where once there was only forest.”  

And now, on the cusp of 2011, it is ever so much worse.   We live in a sick world (in all senses of that phrase) run by an aggregration of dunces. 

On that happy note,

Cheers! ??

Pre-Iridiana, A Found World

Sunday, April 25th, 2010

Early in the last century Sir Arthur Conan Doyle wrote about Professor Challenger, a “scientist” who found bits and snatches of the world of dinosaurs still living, most famously, on plateaux in the Amazonian jungle. There he found living pterosaurs, dinosaurs,  and all manners of strange and wonderfully monstrous animals. Alas – maybe – the animals that Doyle wrote about vanished from the living world in the aftermath of an impact of a rather small asteroid with the Earth, some 65.5 million years ago. During the vast span of intervening years, the Earth has changed. Very dramatically!! The world of the dinosaurs really was not the world of man, but it has only been in the last couple of decades have we been truly able to realize how different these two worlds were from one another.

Until recently, except for the foolishness of the massive floods and perfect gardens found in some of the religious mythologies of the world, if people thought about what the world was like in the distant past, they visualized it pretty much as the world they saw around themselves.   As a scientific viewpoint developed in the nineteenth century, particularly within the basic science of geology, there were many acrimonious debates between those individuals who contended that all changes were gradual and based on the same or similar processes as were seen in action today, the uniformitarianists, and the catastrophists, who contended that many calamitous changes, mostly floods of a truly biblical nature, radically altered and changed both the landscape and the life on it. By the beginning of the 20th century, the catastrophists were pretty much considered to be all wet, and uniformitarianism carried the day, the week, the month, the year, the decade, the generation… but not quite the century.

By the beginning of the 21st century, thanks to some brilliant insight, and a lot of hard work, it had become clear that although the world’s environments had stayed rather consistent for long periods, there have been times of drastic change, after which literally everything, from climate to biota, changed. For most folks, the most notable of those drastic changes was the one that ended the domination of the world’s bioata by the larger non-avian dinosaurs, the Cretaceous epoch, about 65.5 million years ago. Although, by far and away, not the largest of these mass extinction events,  the devestating changes triggered by the impact of a small asteroid off shore of the northern presumptive Yucatan peninsula were damaging enough;  resulting in wholesale changes in the Earth’s biota, virtually every large terrestrial animal species went extinct, along with many marine species.  Subsequent changes in the Earth’s climate resulted in today’s world; a much different globe than that the larger dinosaurs dominated.

Although this event, the Cretaceous/Tertiary Mass Extinction, closed the door on the non-avian dinosaurs, it allowed mammals, more-or-less by default, to adaptively radiate and come to dominate the world.  Nonetheless, the extinction event, while it changed the biota, did not wipe away the evidence of the world that had existed.  That world holds, for many people, particularly evolutionarily oriented biologists, a fascination due the awesomely different biosphere that was present.  

About a month ago, I received as a gift, the book titled, The Cretaceous World, by Peter Skeleton and his coauthors. Over the last few weeks I have been enjoying learning about that long gone world. Very well-written, and exceptionally well-illustrated, the book is designed as a text, but unlike many texts, this one is as alive as the inhabitants of the world it describes are not. Pulling together geological, oceanographic, and biological data, much of it gathered in the last few years, the authors create a world that is awesome in its differences from the present one. From discussing in detail forests at the latitude of Pt. Barrow, Alaska, to describing ferocious storms in the central Tethys seaway, along with the immense deserts of the equatorial latitudes, the authors take the reader on a memorable mental tour of a long-lost world.

I have so enjoyed this book that I want to tell people about it.  In a way, it is the most wonderful type of science fiction, although I am certain the authors would not appreciate that description.  However, they describe in detail a world that changed over the 80 million year history of the Cretaceous, a world based on very hard, and very good science, and have assisted the reader to clothe this world with their mental images.  We really will never know what the Cretaceous world looked like, nor will we ever find out much about the vast majority of the animals that lived there (because they were invertebrates and didn’t fossilize), but we have a good basis for knowing the world itself.  So, what we see in our mind’s eye may be “science fictional,” but it is the hardest of science fiction, that based on and consistent with all the facts.  This world would not be the benign, kind and friendly world of  Jurassic Park.  Humans in the Cretaceous would find the climate oppressive, the flora unfamiliar, the oceans utterly strange, and full of dangerous reptilian predators, although those are not discussed in the book.  And, in general, the megafauna positively frightening and exceedingly dangerous; Cretaceous Park would be a great place for a well-prepared scientist to visit, but you really wouldn’t want to live there. 

The animal life, however interesting, is not the center of the discussion.  While putting the story together for their students, the authors have really given the rest of us a rare glimpse of an alien World, from a geologist’s perspective.   We become aware of the almost familiar orientation of the continents,  but the huge oceanic areas render the land masses of those continents much smaller than what is experienced today.  While the continents are tectonically moving, they haven’t – yet – encountered each other in the massive collisions that have characterized the last 50 million years.  There are not a lot of impressive mountains.  Lots of hills, to be sure, but nothing like the Himalayan plateau, and the Alps are in the future as well.   Coral reefs are the dream of the cnidarians’ future, but – Wow!, this is the world of the Clamrades!  There are huge expances of clam beds comprised of, in many cases, huge clams.  What most geologists don’t really seem to flash on, the author’s of this tome missed it as well, is the amount of biomass that must have existed planktonically in the shallow seas.  These seas were not the clear blue seas of today’s coral reefs, they were gorpy, green, and thick with life.  The huge carbonate “platforms” of the Cretaceous had to feed on something, and clams have a lot higher metabolic rate than do corals. 

And the temperatures!  Baby, it’s hot out there!!!  Diving in the shallow equatorial seas would kill a scuba diver.  There would be no way to dump the body’s excess heat, and any exertion at all would be lethal.  Rather like diving in the hottest extremes of the Persian Gulf today, one could not spend a lot of time in those oceans.  One probably wouldn’t want to, though, as humans could have been considered to a good snack for some of the mosasaurs and other swimming arrays of teeth; LARGE swimming arrays of teeth, that dominated those seas. 

The  Cretaceous world that the authors describe in detail, really for the first time, is in effect, like an extrasolar world, only one that is 65.5 million light years away in space and time.  This world would be a great star of documentaries, although you couldn’t pay me enough to go film the action; nonetheless, I would love to see it.

Enjoy the book and learn about a wholly new place, the Olde Earth.

Until later,