18 July 2010

SUNDAY POETRY: "ABOUT THE TEETH OF SHARKS"

(Photo by
TANAKA Juuyoh (田中十洋), courtesy Wikimedia Commons)

The thing about a shark is—teeth,
One row above, one row beneath.

Now take a close look. Do you find
It has another row behind?

Still closer—here, I’ll hold your hat:
Has it a third row behind that?

Now look in and...Look out! Oh my,
I’ll never know now! Well, goodbye.

15 July 2010

REBIRTH OF A JAPANESE SPIDER CRAB


 

Timelapse of a Japanese spider crab molting. This is the largest arthropod on Earth, with leg spans up to 3.8 meters/12.6 feet and weights of 19 kilograms/41 pounds. The video was shot over six hours in the Enoshima Aquarium in Fujisawa, Japan.

As for the mechanics behind the molt, this from the Alaska Fisheries Science Center about king crabs:
Prior to molting, a crab reabsorbs some of the calcium carbonate from the old exoskeleton, then secretes enzymes to separate the old shell from the underlying skin (or epidermis). Then, the epidermis secretes a new, soft, paper-like shell beneath the old one. This process can take several weeks. 

A day before molting, the crab starts to absorb seawater, and begins to swell up like a balloon. This helps to expand the old shell and causes it to come apart at a special seam that runs around the body. The carapace then opens up like a lid. The crab extracts itself from its old shell by pushing and compressing all of its appendages repeatedly. First it backs out, then pulls out its hind legs, then its front legs, and finally comes completely out of the old shell.

Over the next few weeks, the crab gradually retracts all of its body parts from the outer shell by a few millimeters, while it begins to secrete a new shell beneath the old one. When a crab molts, it removes all its legs, its eyestalks, its antennae, all its mouthparts, and its gills. It leaves behind the old shell, the esophagus, its entire stomach lining, and even the last half inch of its intestine. Quite often, many crabs in a population molt at the same time of year, and their old shells  wash up on the beach. If you find something on the beach that looks like a dead crab, pick it up, open the lid, and look closely inside. If nobody is home, it is a cast-off exoskeleton.
A king crab may molt 20 times in its life. After hatching out as a planktonic larva, it molts 4 times, at 1-2 week intervals, before becoming a small crab. In its first year of life, it may molt 6 more times. The time between molting (the inter-molt period) gets longer with every molt. A 2-year old crab may molt only 3 times, a 3-year old only twice. By the time they are 4 years old, king crabs will molt only once per year. They become sexually mature at about 5 years of age. After that, the females must molt every year in order to mate, but the males molt less and less often. Very old males may not molt for 3 years or more.


To say this is an amazing process is a major understatement, and it has been the focus of research by many scientists for decades. Molting takes place about 15-20 times in the life of a crab. A king crab may molt six times in its first year, four in its second, two or three times in it’s third, and after that, perhaps only once a year. After sexual maturity, the females continue to molt annually, while intermolt periods become continuously longer for the males, so that they only molt once every few years or so.

(Photo from here)

This is actually a lobster larva, but you get the idea.

12 July 2010

DEEP WAVES SEEN FROM AFAR

 Image by the NASA Earth Observatory. Caption by Holli Riebeek.

This Earth Observatory image shows two kinds of waves on the surface of the Indian Ocean near the Andaman Islands. You can also see the venting Barren Island Volcano in the lower left.

The tiny waves running horizontally across the image are regular surface waves driven by wind blowing across the water. The huge waves flowing nearly vertically across the right side of the frame are internal waves, driven by tides dragging the deep, cold, salty waters at the bottom of the ocean over a shallower seafloor ridge. From the Earth Observatory caption:
Internal waves happen because the ocean is layered. Deep water is cold, dense, and salty, while shallower water is warmer, lighter, and fresher. The differences in density and salinity cause the various layers of the ocean to behave like different fluids. As internal waves move through the lower layer of the ocean, the lighter water above flows down the crests and sinks into the troughs. This motion bunches surface water over the troughs and stretches it over the crests, creating alternating lines of calm water at the crests and rough water at the troughs.
It is the pattern of calm and rough water that makes the internal wave visible in satellite images. Calm, smooth waters reflect more light directly back to the satellite, resulting in a bright, pale stripe along the length of the internal wave. The rough waters in the trough scatter light in all directions, forming a dark line.
In DEEP BLUE HOME I spent a fair amount of time writing about the stratification of the ocean. At its largest scale, the motion of the waters of the globe are known as the thermohaline circulation, because they're driven by differences in temperature (thermo) and salinity (haline). Here's a snippet:
Just as gravity drains the rivers of the land, so gravity drains the rivers of the World Ocean. The saltier, colder, heavier rivers sink beneath the fresher, warmer, lighter ones. The three dimensional realm of the ocean is layered with watersheds running over and atop one another in multiple directions. An exploded view of the global thermohaline circulation looks something like an intricately entwined highway interchange system, with layers crossing and bypassing at many levels, in all directions, and at different speeds.
This simplified NOAA diagram is worth a thousand words:


The timescale of the thermohaline circulation is pretty amazing. On the order of a couple of millennia to circulate complete around the world. We currently understand only the broad outline of the system. 

A new and really important piece of the puzzle was only recently added with this paper in April's Nature Geoscience (DOI: 10.1038/ngeo842) by researchers from Japan and Tasmania. They found that waters flowing nearly two miles deep in the Southern Ocean are moving at an astonishing 700 meters/2,300 feet a minute (the fastest deep current yet found), with a flow rate of more than 8 million cubic meters/2,800 cubic feet a second. That's 40 times as much water as the Amazon River. The new current is likely a critical driver of the thermohaline circulation, and global climate.

11 July 2010

SUNDAY POETRY: "THE SAINT AND THE CRAB"


(Photo from Photo Dictionary)

Along the campo, Manin’s bronze winged lion prowled
among the tanned intruders, licking their hands.
Pools of iridescent shellfish
lay open in the restaurant window,

a shop of otherworldly opals, the mussels’ sheen
the skies of a closed heaven, crabs flat on their backs,
their armor intricate trapped plates and escapements.
The squid slumped in its own ink, the octopus appalled

in its slime. Many and ingenious are the postures of death.
But look! There, in a corner, beneath a willowware plate,
a lone crab clicked its claws, creeping
over a casket of walleyed fish,

through a valley of oysters keeping their counsel,
only to shift warily under the shadow of a wine bottle.
Which saint, O saints, watches over the saintly crab?
The man of forks and spears, the man of arrows?

In the Ca’ d’Oro, the stiffened Sebastian takes
each arrow through his flesh like a skewer.
He wears a little napkin around his middle.
Saint, watch over the fragile boat of the runaway crab.

Let him steal his way back to the green lagoon,
go floating down the Grand Canal on his own motoscafo.
Let him take second life, a later martyrdom.
Let him wave his bent claws in a mockery of farewell,

lest we eat in his hollow shell his captive meat.

08 July 2010

SWEET, SALTY DREAMS


The Norfolk Broads from Ashley Ford on Vimeo.


Desperately needed a break from the horrors of the oily world I was laboring in today. So took a little trip to the the Norfolk Broads, a national park in the UK. This video's worth plugging into your good speakers and popping open the full screen. I particularly like the long noses of the grey sealskind of like a cross between our harbor seals and elephant seals.


(Photo of harbor seal by drsteve on Flickr)

(Photo by mgsbird on Flickr.)

...Though Id' still like to toss a BP bigwig or two onto the beach with one of these schnozzle kings, a 2,700-kg/6,000-lb elephant seal harem master... Harrumphh.

05 July 2010

THE MINISTRY OF SILLY BEACH WALKS



Videos of Theo Jansen's fantastical Strandbeests (beach beasts) born at his Windlab in Holland have been crawling the Internet for a while. But this is the first time I've seen an HD film, beautifully shot, and with a haunting score made more interesting by the fact that his Animaris Umerus largely fails to walk... Animaris Humoris?

Here's his description of how a similar species works:
"Self-propelling beach animals like Animaris Percipiere have a stomach. This consists of recycled plastic bottles containing air that can be pumped up to a high pressure by the wind. This is done using a variety of bicycle pump, needless to say of plastic tubing. Several of these little pumps are driven by wings up at the front of the animal that flap in the breeze. It takes a few hours, but then the bottles are full. They contain a supply of potential wind. Take off the cap and the wind will emerge from the bottle at high speed. The trick is to get that untamed wind under control and use it to move the animal. For this, muscles are required. Beach animals have pushing muscles which get longer when told to do so. These consist of a tube containing another that is able to move in and out. There is a rubber ring on the end of the inner tube so that this acts as a piston. When the air runs from the bottles through a small pipe in the tube it pushes the piston outwards and the muscle lengthens. The beach animal's muscle can best be likened to a bone that gets longer. Muscles can open taps to activate other muscles that open other taps, and so on. This creates control centres that can be compared to brains."


Animaris Percipiere.

"Jansen's creatures begin to take shape as a simulation inside a computer, in the shape of artificial life organisms which compete among themselves to be the quickest. Jansen studies the winning creatures and reconstructs them three-dimensionally with light and flexible tubes, nylon thread and adhesive tape. Those moving around more efficiently will donate their "DNA" (length and disposition of the tubes forming their movable parts) to the following Strandbeest generations. Through this process of hybridization and Darwinian evolution, creatures become more and more capable of living in their environment, and can even take decisions to guarantee their survival. The Animaris Sabulosa, for instance, buries its nose in the sand to anchor itself when detecting the wind is too strong to be still standing."
According to Jansen, he usually has only one or two living species at a time. The finished ones he declares extinct and consigns to the boneyard next to the Windlab, where they fossilize, becoming more bonelike over time. 
























The boneyard.

04 July 2010

SUNDAY POETRY: "THE MEDITATION OF THE OLD FISHERMAN"


(Image by camera_obscura/vic from here.)

THE MEDITATION OF THE OLD FISHERMAN
by William Butler Yeats 

You waves, though you dance by my feet like children at play,
Though you glow and you glance, though you purr and you dart;
In the Junes that were warmer than these are, the waves were more gay,
When I was a boy with never a crack in my heart.
    The herring are not in the tides as they were of old;
    My sorrow! for many a creak gave the creel in the cart
    That carried the take to Sligo town to be sold,
    When I was a boy with never a crack in my heart.
     
    And ah, you proud maiden, you are not so fair when his oar
    Is heard on the water, as they were, the proud and apart,
    Who paced in the eve by the nets on the pebbly shore,
    When I was a boy with never a crack in my heart.


02 July 2010

SEAWEED



"Every time we walk along a beach some ancient urge disturbs us so that we find ourselves shedding shoes and garments or scavenging among seaweed and whitened timbers like the homesick refugees of a long war." -Loren Eiseley