california academy of sciences

We are in San Francisco, CA for the opening of our reaction show. Today we explored the Conservatory of Flowers and California Academy of Sciences in Golden Gate Park. Here are a few photos of creatures at the academy.

The top picture is some kind of urchin. Followed by a leather coral, a spotted fish (species?), a hard coral, and a moray eel. Both the fish and eel have patterns reminiscent of reaction diffusion. We also had a chance to see most of the fish shown in our previous posting on reaction diffusion in person.

Fish patterns | Reaction-diffusion in nature

Our Reaction show starts in San Francisco in a few days. Throughout the course of the next month, we will be doing a number of posts on the reaction-diffusion system and its scientific and mathematical basis.  Today’s post was originally going to be titled “top 5 best tropical fish” …. but who can stop at five… You can find these pictures and more in a gallery I curated on flickr here.

Intricate and colorful, the 2d skin patterns of fish are one of the only examples where we can observe Turing waves in vivo.  The skin patterns of some fish change throughout their growth sometimes even into adulthood allowing for the dynamic nature of reaction diffusion to be observed over time.   Scientific studies of the emperor angelfish and the zebrafish have given striking evidence that reaction diffusion (or some mathematically analogous process) accounts for the dramatic shifts in pattern that occur over the fish’s lifespan. Here are some striking examples of reaction diffusion patterns in situ.

The juvenile emperor angelfish (left, photo by Doug Anderson) displays a particularly intriguing radiating stripe pattern. This pattern eventually converts to the one you see in the next photo. As the fish grows, the pattern “unzips” along the Y branch points that form to maintain an even distance between stripes. Eventually, this results in an adult fish where the stripes are evenly distributed with no branch points.

The puffer fish below are closely related species, yet they display very different patterns! Since they are closely related, it is likely their patterns have a similar molecular basis. The responsible chemical mechanism must be able to account for the dots, stripes and polygons exhibited.   Reaction diffusion systems have just this property; producing dots, stripes, polygons and combinations thereof when given different parameters.

Boundary conditions like the eye of the fish tend to determine stripe directionality. For the Acanthurus lineatus (below left) and the young Arothron mappa (below right) this results in the pattern orienting perpendicular to the boundary.  In other fish like this blowfish, the pattern may orient parallel to the eye boundary instead.

Reaction diffusion can also account for more complicated patterns like these.  On the left is a Sailfin Tang whose dense dot and stripe pattern overlays a larger macro scale pattern of stripes.  On the right a Napoleon Wrasse whose swirling pattern shrinks in scale markedly as it moves away from its eye.

These photos were taken from a diverse group of photographers on flickr, click each image to visit their photostreams. Interested in reading more about reaction diffusion experiments involving fish? I’ll be posting a review of some interesting experiments soon. I also recommend the website of the Kondo lab which has many of their papers available as pdfs.

Zoanthus sociatus

I went into Boston this week and spent an afternoon soaking up inspiration at the New England Aquarium.  As usual, I spent some time transfixed at the live coral display.  I particularly love these guys, who are Zoanthus sociatus or Button Polyps.  They mostly reproduce by budding asexually and thus form dense colonial mats.  Wikipedia tells me that since they are a member of Hexacorallia each polyp should have tentacles in multiples of six, but I’m too lazy to count.

ice formations

We spent the weekend in the Catskills visiting with friends and family.  On Saturday we took a 4 hour hike up Platte Clove.  I found many unusual ice formations.  This one reminds me of a map.   I have no idea what process created this pattern.

Other patterns had much less mystifying origins, like these frozen bubbles I found at the base of the waterfall at Blue Hole.

purple and yellow

you may notice that we’re in the process of changing our blog! it looks different now…

On the left, Purple Beautyberry (Callicarpa dichotoma) as seen at the Arnold Arboretum in Boston earlier this fall.  On the right, a processing sketch.

fall

On a recent trip to the Arnold Arboretum, we found these perfectly decaying Himalayan Hydrangeas.

rivers and tides

Today I watched Rivers and Tides, a film about Andy Goldsworthy.  I’ve been putting off watching it for several years now, but when I saw it was on instant watch on Netflix I finally went for it.  Goldsworthy is one of my favorite artists.  I became aware of his work in college, right around the time I was beginning to consider pursuing art rather than science.  He works in nature with nature and his works are ultimately about nature as well.  Using water, rock, plant matter, and dirt, he creates site specific pieces that, at best, expose the inner working of nature.  The works really explore the limits of the materials that make up the site and then reconstitute them into an artwork. He’ll take something simple, like how rocks or leaves vary and in color and transform it into something spectacular and surprising by carefully reordering them into a perfect spectrum.  His pieces often fall into several categories: a rock balancing project, a spectrum piece, pieces that form perfect circles or twisting lines.  The movie is intriguing because you get to know not only the work but also the man and his obsessions.

I find his ephemeral projects the most satisfying.  For instance, Goldsworthy makes a chain of leaves held together with thorns.  He then places it in the stream and watches it.  As the chain flows down the river, it threads itself through rocks and riffles, when it moves through a pool it begins to spirals; ultimately it becomes a visible line we can read, a register for the forces in the water.  In another project, he collects red rocks from the bottom of the stream and grinds them up into a fine powder.  Placing the powder in the small neighboring pockets of stone creates shocking blood-red pools.  A simple action, yet he draws many parallels between rock and life, the cycle of stone from sediment to rock and back.  He exposes what was there but unseen.

Overall the film is slow paced but with excellent visuals and music by Fred Frith it’s a pleasure to watch.  Here are a few screen captures I grabbed of the film.

a few favorites

1. Vases by Ikuko Iwamoto, 2. Voussoir Cloud by IwamotoScott, 3.+4. photos of basketstars by jrixunderwater, 5. art by Tara Donovan, 6. hechima paper chair by Ryuji Nakamura , 7. Frost aluminum system by Mars, 8. Romanticism Shop by SAKO Architects , 9. glasses to stack by Propaganda, 10.  Martian crater filled with perfect cellular sand dunes by NASA

David Bowen and Philip Beesley

We were invited to SIGGRAPH this year to be artist’s in residence in the studio.  Two of the other AiR’s were David Bowen and Philip Beesley.  They both also had works featured in the BioLogic art gallery.  It was interesting to hang out with them and hear them speak about their work.David creates simple machines which translate the movements of people, animals, plants or natural forces into other media. His project on view at the conference was called “growth rendering device” (pictured on the left). It functions like a ink jet printer, tracing the shadow of a pea plant, once a day over it’s entire lifespan from sprouting to withering away. The piece on the right, 72 stems, uses dried stalks of Queen Anne’s Lace as antenna’s to sense the almost imperceptible fluctuations of airflow caused by the presence of people. The installation responds to such stimuli by emitting chirping sounds which combine into a layered chorus as participants explore the gallery space.

Philip Beesley is an architect who, in addition to his architectural works, has been pursuing the idea of an architecture of geotextiles.  These geotextiles would be fabrics / materials of repeating robotic units which together form complex ecosystems that function in numerous ways.  (like perhaps harvesting power and structuring heating, cooling and ventilation).  His piece on display was Hylozoic Soil, composed of many repeated units of laser cut plexiglass, with arduino’s powering reactive muscle wire limbs covered in ethereal mylar feathers, with some hyper-dermic needles throne in to add that menacing feeling.

Click on the pictures to check out their websites, they both have numerous other intriguing projects.

Insectarium

We spent last week in New Orleans for SIGGRAPH where we were artists in residence.  We got there a few days early to check out Louisiana; one of the places we visited was the Audubon Insectarium.  What is an Insectarium you ask? Well it is like an aquarium or zoo, except focused on insects.  They did not have as many live specimens as I would have liked but they had a whole room near the end of the exhibition covered wall to wall in prepared specimens, laid out in a very artistic manner.

They were drawing with bugs.  This is the part I really enjoyed.  Here are a few of my pictures: