Morphology

I’m trying out new layouts today to make the blog easier to navigate. Please bear with me.

Tue, 14 May 2013 14:38:00 -0400

I’m trying out new layouts today to make the blog easier to navigate.

Please bear with me.

Hey there! Thanks so much for your continued patronage. To be honest, I’m surprised that...

Thu, 02 May 2013 00:23:00 -0400

Hey there! Thanks so much for your continued patronage. To be honest, I’m surprised that anyone still reads my blog after my year long hiatus.

A lot of things happened. I graduated from my program, losing access to my lab. After my brother passed away, I moved across the country and went to China several times. Right now, I’m having a hard time finding a job related to biology, so I’m working an office job in the meantime.

But all that’s irrelevant. The primary reason I stopped posting, was that, I lost sight of where I was going with this blog.

When I originally started, I was just posting random pictures from my life, interspersed with stuff like drawings, memes…etc. My life just happened to include a lot of morphology.

As time went on, the blog became more and more involved and “educational”, gaining “science outreach” status and thus drawing the attention of the academic and professional community. While this is a good thing, it also prompted a certain level of professionalism and quality, which I felt like I had a hard time living up to.

Now that my audience included not only tumblr users, but also government institutions, university professors and museum curators, etc, what do I write? How do I keep it interesting for both science professionals and general audience alike, and still have it be accessible? Should I strive for tumblr virality to reach more people, or write longer indepth articles that impart more information with less viral impact? Should I strive to educate at all? How much should I interact with the audience? Is it still appropriate to post interesting non-biology things or personal things?

These questions (and more),have kept me silent and conflicted for the past year. And throughout all this, I continued doing hundreds of dissections and skeletal prep, everything from chameleons, to tigers to sharks….etc.

I’m back. I don’t have any good answers, but not trying isn’t helping me. Moving forward, I’m going to try to strike a balance, between accessibility, audience, and purpose, and hopefully, I can still keep it MY blog, rather than a generalized anatomy/morphology infodump blog.

In the end, what I really want to do, is to reveal, acknowledge, and appreciate, this hidden world, that exists inside all living things. So beautifully alien, so intimately close and so breathtaking in its ingenuity.

Thanks again for your continued patronage…… lets go for a ride.

- Helen (ArsAnatomica)

I always felt that photos did poor justice to the breathtaking...

Sun, 28 Apr 2013 15:53:00 -0400

I always felt that photos did poor justice to the breathtaking dimensionality of skulls, so lets try something different. (Making animated gifs is something I’m somewhat new at, so bear with me here.)

This is a Gaboon Viper skull.

Gaboons are large (highly-venomous) African vipers, that hold the unique distinction of having the longest fangs in the world, with the ability to inject more venom than any other snake. There’s usually two (or more) fangs on each side.

In the photo below, you can see a groove at the base of the foremost fangs, through which the venom duct enters the hollow fang.

Most people think of the skull as a single bone, with a detached...

Sat, 27 Apr 2013 00:27:40 -0400

Most people think of the skull as a single bone, with a detached lower law. In reality, the skull is comprised of a number of smaller bones that fuse during development. It’s a primitive feature, whispering through the proliferation of osteoclasts, of an ancient arms race and a story of segmented bodies gliding through endless silent seas.

These days, most mammals, birds etc, have fairly solid skulls, but the further you go down in the evolutionary latter, the looser skulls become.

Fish skulls are mostly still made up of loosely connected bones, that often breakdown into their components when cleaned for study. “Articulation” is art of making sense of it all and putting it all back together.

This is a Cutlass fish skull.

Cutlass fish are large eel-like fish that swim vertically, darting upwards to grab prey with their very large fangs.

Here’s a closeup of the fangs. They’re razor-sharp on the leading edge and barbed, making it difficult for prey to escape.

Due to their inherent flexibility, snakes have very loosely...

Fri, 26 Apr 2013 04:53:13 -0400

Due to their inherent flexibility, snakes have very loosely joined skulls that occassionally require assembly.

This is an eastern diamondback rattlesnake.

The skull of a Bengal tiger rests along side the skull of a...

Thu, 25 Apr 2013 03:22:23 -0400

The skull of a Bengal tiger rests along side the skull of a domestic cat.

Notice the proportionally smaller braincase and eyes in the tiger, and the much larger flanges for muscle attachment, in comparison to the overall size of the skull.

As animals scale up in size, more muscle is needed to bear the additional weight and counteract the effects of gravity. To anchor the increased mass of the muscle, bones become more robust. Thicker, heavier, with larger flanges, and deeper hollows to provide the additional muscle with leverage.

It’s a cyclic system. More muscle is needed to support heavier bone which in turn supports more muscle…etc.

You’d think it could go on forever, but as animals become larger and more powerful, they also become heavier. For land predators, the cycle reaches a cutoff size when the increasing weight begins to negatively affect agility, maneuverability, and the ability to successfully catch prey.

Thanks for the fascinating blog, although I can't quite fathom the thought processes that lead to manually collecting roadkill skunk juice. Made for a compelling read though, especially with those excellent diagrams.

Tue, 03 Apr 2012 18:19:00 -0400

Hey there, thanks for reading my blog.

I have to say that it was largely curiosity driven.

What did the spray look like? How did the glands work? Anal glands in most mammals are not muscular, so what powers the discharge of the spray? Skunks are such common-place animals, but they’ve got this adaptation that’s really quite unique and bizarrre.

The spray is incredibly volatile and diffuses into the air really easily, but smell-wise, it could be worse. I took a sculpture class once and used sulfur-based plasticine (a type of clay). It smelled just like that. It’s strong, but not really intolerable.

…. and yes, the practical joke potential of this did cross my mind, but I never did anything with it since it was too hard to store, and would permeate any container.

The mechanism of grasp

Sun, 01 Apr 2012 23:27:00 -0400

While looking at the little screech owl, I took a series of photographs and made this gif to illustrate the of the automatic grasping action of the talons.

The structure of bird feet is set up so that the foot automatically grasps when the ankle joint is bent.

This automatic grip allow birds to sleep while perching, and for raptors clench/grasp prey as the leg is folded on impact.

The mechanism of the foot is ingenious…. there’s no muscle in there at all.

The foot is powered entirely by a pulley system of tendons.

Two tendons that run along the back of the leg, Flexor Digitorum Longus and Flexor Hallucis Longus are responsible for the automatic grasp. The former pulls the forward facing toes, and the latter pulls on the hallux, or back toe.

I drew a schematic diagram of these two tendons here:

It’s particularly interesting in raptors.

Raptors swoop down on prey with talons/legs outstretched. The impact with the prey folds the raptor’s legs against its body, causing the talons to clench automatically, tearing into the prey. The automatic grip is strong enough to kill, and is what allows many hawk species to catch and kill other birds in midair.

The ingenuity and perfection of this mechanism is mind-blowing.

Eastern Screech Owl

Sun, 01 Apr 2012 13:50:00 -0400

Isn’t he cute? He looks almost alive.

Unfortunately, he’s not.

This little guy is an eastern screech owl. Following a heavy storm, he was found dead on a residential street, entangled in some fallen branches at the base of a utility pole.

I’ve previously posted a picture of him before. I’ve never had the opportunity to look at owls close up.

He’s recently dead, his eyes have not yet begun to cloud or dessicate. Owl eyeballs are not spherical, they’re bell shaped, and fixed in their sockets.

Since the eyes are fixed, owls move the entire head instead and can turn it almost all the way around.

There’s another lesser known effect of eye immobility. Owls have excellent vision but have close range astigmatism. The area just in front of them is always blurry.

But that’s okay, because that blind spot is covered by crines. Crines are specialized whisker-like feathers around the beak area that extend into the blurry zone.

These whiskers are highly sensitive, and allow the owl to “feel” for it’s food items, since it cannot see them.

The owl’s capacity for silent flight comes from the fimbriate border of it’s flight feathers. This comb-like edge breaks up turbulence over the wing to reduce sound.

These nubbins on his talons are called spicules, and are modified scales. Theyre common in birds of prey, and help improve grip by increasing the surface area, the same way fingerprints function in humans.

Owing to the circumstances in which he was found, we initially believed him to be another unfortunate motor vehicle victim, but soon realized that this was not the case.

There’s two blackened spots at the tips of his talons.

His underside is a charred mass of feathers, and he’s got a faint “burnt” smell. The skin on the inside of his leg is roasted to a golden brown. The word “rotisserie” comes to mind.

I guess that power line wasn’t a safe perch after all.

Can’t pass up the opportunity to make some more drawings.

Zoo Kingdom for Facebook

Thu, 12 Jan 2012 03:11:00 -0500

A while ago, I was asked create a series of fact cards for Zoo Kingdom, a facebook game made by Blue Fang Games, the makers of Zoo Tycoon.

Each species introduced in the game, had a series of fact cards that aimed to introduce some aspects of their natural history, morphology and ecology.

I made about 150 of these. Below are my personal favorites.

Questions.

Tue, 10 Jan 2012 23:12:00 -0500

I haven’t updated in a while. I’m very sorry.

I would like to offer my gratitude to everyone who as taken the time to inform me of their interest in my blog. I’m deeply grateful for your support, and am elated to see so much interest in morphology.

Unfortunately, It’s been very difficult to keep up with the volume of correspondence I receive. I’m sorry I haven’t replied to all of your letters.

Many of the letters I receive often contain similar questions, so I’d like to take the time now to address these recurrent concerns.

Do you kill these animals or are they already dead when find them?

No, all of the specimens are collected from natural deaths, donated or already part of the collection. Necropsy is rather interesting. Whenever possible, I try to determine cause of death. Etched in each bone and woven into the fibers of each muscle is the life and death of the individual.

It’s a story that deserves to be told.

How do you go about bleaching clean bones?

“How to bleach?” is by far, the single most common question I encounter. There is no single answer and everyone has different techniques. Personally I use non-chlorine bleach. It is a concentrated Hydrogen Peroxide solution, and is available at most grocery stores.

The concentration depends on the delicacy of the specimen. I use it straight for larger, more robust things such as deer. For smaller, more delicate specimens like birds, I dilute it with water and monitor closely to avoid over bleaching.

During bleaching, I take out the bones once in a while, and wash and dry them to check. You can always continue to bleach if the bones are not sufficiently clean, but over bleaching will damage bone.

Will you send me some reference photos of a specimen?

Yes, but I get a lot of requests for photos, so it might take a while. Please limit requests for photos to about 5 per request. Be specific about what you want and I’ll check if I have anything that suits your needs.

Is your blog named after a quote?

No. Ars Anatomica is Latin for “The Art of Anatomy.”

What do you do with the skeletons you clean most of the time?

It varies. I’m often asked to clean stuff for various departments and faculty at the college. These specimens (often rare and cool stuff,) are cleaned per departmental specifications and returned. Specimens that belong to me personally are kept. I may try to mount them depending on condition. Animals collected from roadkill often have large scale bone shattering in the skull, vertebral column or rib cage and pelvis areas. These types of shattering injuries are difficult to repair, making many of these skeletons unmountable. If I have a spare pelvis lying around I’ll try to swap it out.

Most of the time. I just enjoy looking at them. Bones read like good books.

What did you study/ major in?

I majored in art and biology. For the art aspect, I focused on illustration. For biology, I focused on tetrapod morphology.

The pregnant doe that you posted about is the worst thing I have ever seen. How can people be so cruel?

I get a decent amount of mail about that post. As tragic as this accident was, I don’t think it was avoidable. She was killed in the wee hours of the morning, on an unlit highway that was heavily wooded on both sides. The speed limit was 75mph.

It’s awful, but I can’t think of any way that this accident could have been averted. The doe and the driver were both at the wrong place at the wrong time.

I’m a biology student. How do I learn to draw anatomical diagrams?

I’m not sure that I can offer any advice beyond the importance of general practice. It’s true that I draw a lot of anatomical diagrams, but I also enjoy drawing a large variety of random things. I think every little bit of practice helps. Even if you want to draw diagrams, it’s important to not confine yourself to drawing only diagrams.

Apologies for the delay and thanks again for your interest and support.

For viewers with specific concerns, data, literature and photo requests. Please accept my apologies. I’m slowly working through them.

Making sketches of an Eastern Screech-Owl …a sad power...

Tue, 10 Jan 2012 21:37:00 -0500

Making sketches of an Eastern Screech-Owl …a sad power line fatality.

To use him to educate others, is the least we can do.

He’s a magnificent little creature.

Making sketches of a shortnose gar. These guys have very...

Tue, 06 Sep 2011 21:45:00 -0400

Making sketches of a shortnose gar. These guys have very interesting jaw structure.

Baby Skunk Necropsy

Thu, 01 Sep 2011 15:54:00 -0400

Taking apart the baby skunk.

In the interests of length, this entry is mostly about internal organs.

All images are linked to high res versions, click to view.

NOTE: This post contains graphic images of an animal being skinned and photos of internal organs. It is NSFW and R-18G. Click “Read more” if you wish to see it.

All prep work begins with skinning. In trauma, the elasticity of the skin is deceptive, often masking the true extent of injuries.

There’s not a single scratch on this little guy. Beneath the skin, a large tear in the muscles of his flank has allowed the intestine to slip into the space just beneath the skin.

He’s been internally disemboweled.

The location of the tear on his left side, indicates that he was hit from the opposite side.

It’s a classic vehicle hit injury. I see it all the time. In fact, here are two other specimens with nearly identical injures. A pregnant doe and a pregnant cat.

Here’s a shot of the hind quarters. The anal glands of the skunk are now exposed. In this photo of the thigh area, I’ve marked out the location of the underlying bones. The bright blue areas denote “bony landmarks”, areas in which bones come to the surface of the form. These are useful for drawing.

According to a veterinary manual I once read, the anal glands of a skunk are the size of grapes. This baby skunk is so young that his testicles are not yet descended, yet his anal glands are nearly adult size. Priorities…

Here he is fully skinned. His pelvis is broken, torn apart along the pubic symphysis, or the area in which the two halves of the pelvis join. The abdominal wall is torn there as well.

It’s another typical vehicle hit injury.

The smooth watery surface of the liver pushes into view through the abdominal incision I’ve made.

…and it’s a mess too. Beneath, the smooth surface of the lobe, the liver is hopelessly lacerated, nestled in a sprawling ruin of blood clots.

Liver laceration is one of the most common injuries in blunt force trauma to the torso. The soft nearly gelatinous organ is filled with small fragile blood vessels. It fragments easily, even if the muscular body wall remains undamaged.

Within the folds of the liver, the gallbladder has begun to leak bile, staining the liver a bright saffron yellow. The vividness of the color is amazing.

I’ve excised the liver. I’m often awestruck by the beauty of these structures that remain hidden in life. The fluidity of form and subtle transitions of color are flawless.

It’s so beautiful. /sigh

I love this photo. I could probably crop it, mat it nicely, and enter it in the local photo club competition or something.

Returning to anatomy….this photo clearly shows the structures associated with the gallbladder.

The liver produces bile, which travels through the hepatic and cystic bile ducts to be stored in the gall bladder. During digestion, bile stored within the gall bladder travels back down the cystic bile duct into the common bile duct and into the small intestine, to assist in the breakdown of fats.

In humans, the removal of the gallbladder is a common surgical procedure. In that case, the liver simply switches to producing bile on demand, rather than storing the excess.

Here’s the stomach, it’s very full. Opening the stomach and examining the contents is the highlight of every dissection. It offers a glimpse into the animal’s life, dietary choices made unaware of impending demise.

The folded back stomach wall reveals the gastric ruggae, folds in the fleshy wall of the stomach that help increase it’s surface area.

There’s a furry object inside…. It’s partially digested…

Do you see the claws?! I’ve marked them out with blue arrows. The yellow arrows denote the bones of the wrist…. It’s a paw.

It’s the front paw of a rabbit…. this is my lucky day. (It actually looks like the left one.)

The diaphram sits at the end of the abdominal cavity. Behind this fleshy muscular wall lies the heart and lungs. The muscle fibers radiate outward from the center, attaching at the border of the ribcage.

Slightly to the left, there’s a hole in the diaphragm (red arrow). This is called the esophageal hiatus. The esophagus threads through this hole to enter the stomach.

Here’s a shot of the structures of the lower abdomen.

Notice the ureter inserting into the bladder, and the sperm duct (vas defrens) inserting into the prostate. This bottom photo includes both the kidney and the tesicle.

Between my fingers is the kidney.

At the side of the kidney is a opening called the “hilum”. Through this hole, the renal artery (blood to the kidney), renal vein (blood coming out of kidney) and the ureter (urine exiting the kidney) enter the organ. That’s the three strands in the photo.

Inside the kidney, bundles of filter-like structures form units called “renal pyramids.” The filtered out urine collects in a hollow called the “renal pelvis” and flows out the ureter into the bladder.

These are in infamous anal glands.

Most mammals have anal glands, they produce oily secretions used to identify the individual. In skunks, these are huge and highly developed.

These glands are very muscular, there’s two major muscles that cover the surface, set perpendicular to each others. I don’t know what the names are, nor can I find any info on them.

In these photos, I’ve removed the anus along with the glands…it’s impossible to remove the glands without causing damage to associated structures. People talk about descenting skunks/ferrets, declawing cats as casually as if animals are assemblages of readily detachable parts…..trivializing the true invasiveness of these procedures.

Skunk spray is bright yellow.

It’s a thin, almost watery oil that readily permeates most plastics and latex gloves. It’s surprisingly volatile, a small amount will rapidly vaporize into an enormous area.

I was able to express around 2 -3ml or so of the fluid from the glands.

This baby skunk was picked up yesterday. His teeth are perfect and show no wear. Elongated front...

Wed, 31 Aug 2011 22:06:09 -0400

This baby skunk was picked up yesterday.

His teeth are perfect and show no wear.

Elongated front claws for digging.

He’s very small

This poor little guy is just a baby. He’s only the size of a squirrel and probably less than two months old. Just like the fawn, he was probably crossing the street with mom when he was hit. He’s still on his first coat of soft baby fur.

While winter seems to have the greatest number of roadkill as animals disperse. Spring and early summer are sadly a time that a lot of babies die. Depressingly, the speed limit for the road was only 15mph.

Collection Lineup

Wed, 31 Aug 2011 22:04:34 -0400

Here are some old and new photos of skulls I cleaned. With the exception of the sugar glider, these are all local North American species.

Skunk, Coyote, Bear, Deer.

Coyote, Spotted Skunk, Black Bear

Black bear

Crow Skull

Marrow cavity of a groundhog pelvis.

Cervical & thoracic vertebrae from a groundhog. Most burrowing animals have robust neck vertebrae that are tightly joined.

A closeup of the sugar glider skull. Notice the missing coronoid process on the jaw and the broken zygomatic arch.

This is a detail shot of the front paw of the sugar glider that I put together here. It’s still articulated by natural connective tissue.

Happy Birthday Mimi!

Sat, 06 Aug 2011 01:34:00 -0400

Today is my brother’s birthday.

He is officially 20.

Mimi is adopted. Twenty years ago, he was picked up from a box of free kittens outside Walmart.

He was one of a litter of five. At the time, he was only three weeks old. We fed him with a dropper until he was weaned.

He’s been with us ever since.

We go many places together.

We have many adventures. Here he is crossing a creek.

We are shopping for frozen foods.

Mimi has been through a lot. He’s a little survivor.

Due to his age, he has some health problems… but we still enjoy every day together. From now on, Mimi is going on 21.

Color and detail II

Wed, 03 Aug 2011 16:26:34 -0400

It’s often the case, that only in death can many animals be examined in detail; their intricacy of texture and form eludes the eye admidst the fleeting motion of life.

I had originally put this together with the previous post, but had trouble loading so many images.

Click on the images for high res photos.

The chin scales of a timber rattle snake.

The head of the smooth fronted caiman. If you take a close look at scales along his jaws, you’ll notice that each one has a small dot at the center.These are mechanoreceptors. Each dot is a dome of skin that covers a nerve ending. They’re used to detect slight disturbances in water, allowing the animal seek prey in even murky water. All crocodilians have these.

The underside of the caiman. Notice the pattern of scales surrounding the cloaca and on the limbs.

The head of a diamondback rattlesnake.

This large coastal carpet python belong to my friend Aaron. He lived in the herpetology lab for years until he was killed in a lab wide epidemic of unknown origin that killed most of the snakes in the lab. We never learned the origin or even the specific nature of the disease, although we suspect that may have had something to do with the introduction of a wild snake into the lab.

He has a really interesting ventral pattern. The photo doesn’t do justice to the brilliance of his yellows and greens.

Here’s a detail of the heat sensitive pits along his jaw. They’re actually perforations in the scale that begin as in dentions at either end.

Color and detail

Wed, 03 Aug 2011 16:02:00 -0400

It’s often the case, that only in death can many animals be examined in detail; their intricacy of texture and form eludes the eye admidst the fleeting motion of life.

Click on the images for high res photos.

This is parakeet.

The projections on the foot of this red tailed hawk are called “spicules.” They are specialized scales that increase the surface area and help improve the hawk’s grip, allowing it to take better hold of struggling prey. Spicules are particularly prominent in birds of prey that feed on fish, like osprey.

The wing of a raven in black and iridescent blue.

As an invasive species in the US, the European starling is much maligned. They are the target of many pest management efforts, and represent such an ecological disaster that it’s actually difficult to find information on starlings written in anything bordering on a neutral tone.

I’ve always thought of them as unremarkable, until I had the opportunity to see this one up close.

They’re really quite beautiful aren’t they? Perhaps the admiration that must have belied their misguided introduction is somewhat ……..understandable.

This guy was found dead in winter and is in his non-breeding plumage. You see how in the above photo, the white tips of his feathers are chipping off? By spring, he would have lost all his white “stars”’ to enter his glossy black breeding plumage.

I took this a few days ago, during a routine trip to the...

Wed, 03 Aug 2011 00:44:14 -0400

I took this a few days ago, during a routine trip to the park. The doe appeared for less than a second. Mimi remained oblivious to the whole event.

It’s an amazing shot.