Thursday, December 31, 2009

light vs. dark

being that it is the holiday season, i figure a discussion of the intricacies of edible fowl is in order.

on the menu: light vs. dark meat

i'm a vegetarian, but i'm not afraid to say that birds are delicious. i think that a lot of americans would agree with me: on thanksgiving alone, 45 million turkeys were consumed in the US. that's about a turkey for every seven people, holy smokes!

if you are a bird-eater, you have probably been asked if you prefer light or dark meat. the light meat is generally the breast and wing muscles, whereas the dark meat is the thigh and leg muscles. the difference in coloration is due to this baby:

myoglobin! myoglobin is a nifty protein found in the muscle fibers of vertebrates. it has a REALLY INSANELY high affinity for oxygen, which is integral in the proper functioning of mitochondria.

mitochondria are the bits in cells [organelles] that generate energy in the form of ATP [adenosine triphosphate]. nestled in the mitochondria are our myoglobin proteins, which supply the oxygen to the mitochondria as they "do what they do"

though they ARE the superstars of ATP production, mitochondria are not the end-all of energy-makin' in the cell. a process known as glycolysis occurs outside of the mitochondria, and while it doesn't produce a lot of ATP, it does have a redeeming factor: it doesn't need oxygen in order to make it! that's called anaerobic respiration.

here's a diagram with a lot of acronyms and big words differentiating the two:

the blue is what happens within the mitochondria [oxidative phosphorylation] and the rest is glycolysis.

okay, all this stuff is great and all, but i still haven't addressed the coloration difference. c'mon!

SO. as you may be able to see in the diagram of the myoglobin protein, myoglobin has an iron [Fe] molecule in the middle. iron has a reddish quality about it.

thanks,, i'm sure it was really necessary to put your name all over that picture of pure iron powder! cool

anyway, in order to get at what i'm trying to get at, i'm going to put all the information i've presented in a neat little list:

1. myoglobin has a high affinity for oxygen and is found in mitochondria
2. mitochondria make a LOT of energy [ATP] using oxygen [oxidative phosphorylation]; the process of glycolysis makes some energy without oxygen
3. myoglobin is red due to an iron molecule

and a list of some knowns i will present right now:

1. turkeys use their legs a lot, and consequently need more energy in their thigh and leg muscles.
[=> oxidative phosphorylation provides most of the energy for the leg muscles in fowl]
3. breast muscles are not used very much by fowl, and thus do not need as much oxygen
[=> glycolysis provides most of the energy for breast muscles in these birds]

conclusion: light meat is light because it has less mitochondria [myoglobin], dark meat is dark because it has more.

HA! made you learn some stuff so i could make that simple little statement.

so, light or dark?

Tuesday, December 29, 2009


i went to the garden/pet store today with my sister to get a tank for her new fish, Dog. i let her get the fish stuff while i looked at the birds. there was a cockateil, two lovebirds, about seven parakeets, and some finches.
the finches at the store were called society finches [see above]. aptly named, as they were white, black, and beige. very sophis.

finches are songbirds in the order passeriformes that typically eat seeds, nuts, and insects. daily activities include foraging and flitting around looking cute. they can be found pretty much all over the world, and i would guess this is because seeds can be found pretty much all over the world. a common finch you have probably seen is the house finch:

careful, don't confuse it with the purple finch! i did that once, how embarrassing for me. ornithologists can be so stuck up sometimes.

that's a map showing house finch radiation throughout the years in the US. i wonder if there is a west-coast subspecies and an east-coast subspecies?

though finches can be found all over the globe, the most famous ones are those of the galapagos.

the galapagos finches are really famous because of ole chuck darwin. he dropped in for a visit to the islands and observed that there were many different species of finches, each fulfilling a different ecological niche.

i guess darwin pondered on this genetic diversity really hard and came to some important conclusions or something.

les pensées d'ole chuck bring us to the concept of "adaptive radiation."

what? you want me to explain adaptive radiation for you? well, i can sure take a crack at it!

essentially, every animal wants to survive and reproduce. and in an ideal world, every animal would. BUT! they can't. it's all about resources; there is simply not enough food or space in the world for the indeterminate growth of all populations.

[laws 2 live by: energy cannot be created or destroyed, and hey neither can mass because e=mc squared, babe. errthing's limited]

in order to solve the competition-for-resources problem, some animals have dominance hierarchies, some animals are territorial...

and some animals evolve to fit different ecological niches. this is the case of the galapagos finches.

[niche: (ecology) the status of an organism within its environment and community (affecting its survival as a species). thanks, webster online!]

a couple of million years ago, there was one species of finch on the galapagos. to avoid competition for food, morphological changes [like bill shape, size] favored by different finch diet plans were selected for.

if i'm not eating the same type of nut that you are, we don't have a problem with each other, competition avoided, no need for fighting, everyone's happy. capish?

remind me not to say capish.

anyway, what i'm TRYING to say here is that there is a positive correlation between niche specificity and survival rate. it doesn't even have to be related to food; there are birds that have successfully speciated so that one species prefers to nest in the tops of trees, another in the middley bits, and yet another in the bottom branches. neat!

so, back to finches. like most everything, i can narrow it down, but i can never choose my absolute favorites. here are the battles between finches i have in my head. i may or may not lose sleep over them.

1. european goldfinch VS. american goldfinch

i mean, the american goldfinch is really, really cute. it flies by taking a couple of flaps [whilst chirping] and then putting its wings by its side, falling a little, and repeating the process. plus, its the state bird of iowa.

on the other hand, there's the european goldfinch, which is more severe looking. its got great coloring and patterns on the wings. i would make a joke about it being european, but i don't know enough about general european trends to feel okay with doing that. uh...euro! baguette! renaissance?

the other battle is the battle of the grosbeak finches.

2. evening grosbeak VS. rosebreasted grosbeak

i just love grosbeaks. these guys are both native to iowa-- the evening in the winter and the rose-breasted in the summer. "gros" means fat in french, that probably has something to do with the naming. i haven't seen either in real life yet, and i anxiously await the day[s] when i do see them. i may or may not have a heart attack when i see one or both. ow!

which finch wins your heart over?

Sunday, December 27, 2009


the amniotic egg is the single most important advancement in the terrestrialization of vertebrates.

i don't think terrestrialization is a word.

before The Amniotic Egg, amphibians [the most derived vertebrates at the time] were dorking around in water/on land/in water, always one foot out the door ...

then egg-laying reptiles hit, and SHAZAM! all of a sudden the marine environment was unnecessary for vertebrate survival. bird eggs are a lot like reptilian-dinosaur-lizard eggs; the reason for this is that birds are actually considered part of the reptilian clade.

according to Paleontology, fossilized eggs are hard to come by. the oldest egg found is thought to have been laid by a pelycosaur, aka a sailback:

[to note: mammals eventually evolve from the pelycosaur lineage]

though birds are on the whole terrestrial, the embryos still need a watery environment to develop in, and the egg provides that. other things an egg provides for a birdembryobabyfetus:

1. protection
2. nutrients
3. waste storage
4. free continental breakfast and wireless!
whatta deal.

instead of trying to explain what happens inside of an egg as it develops, i will just show you this:

the inside is great and all, but my favorite part of the egg is the shell. hel-lo, it's comprised of one of my favorite chemical compounds, calcium carbonate (CaCO3)! Calcium carbonate is also featured in: bones, chalk, limestone, fossils and shells of marine organisms, cement, and tums. wow, how versatile!

i figure a fertilized egg needs two things in order for the birdembryobabyfetus to "come to term," as it were:


enter nests.

bird nests hold the fragile egg as the birdembryobabyfetus develops. in some cases, nests also serve as a home to young chicks. nests are really diverse: of the types, you got your cavity, your bark, your platform, your spherical, your pendant...the list goes on. within those, many different kinds of materials are used. cool, natural architectural triumphs!

my favorite is the nest that is made by a cave-dwelling swift [aerodramus] from its own saliva.


i guess it's a delicacy in china in a soup called bird's nest soup. ah, quelle originalité.



the shoebill lives in egypt and is particularly bizarre looking--when i first saw a picture, i thought it was a muppet.

interestingly, shoebills could be the missing link between storks and pelicans! wikipedia told me that one, so i don't know if it's true. i can see it, though-- the neck and head positioning look pretty stork-like, but lookit that bill! go-lly, i would say that the shape is reminiscent of a pelican. a lot of fish eating birds rely on serrations on the bill to secure the fish, but shoebills and pelicans just rely on having REALLY BIG MOUTHS!

despite their huge size, shoebills can [and do] fly.

the slotting on the primaries promotes gradual lift, which is great for big ole soaring birds who don't want to flap too much. what the slots do is direct air over the wing surface, which creates favorable pressures both above and below the wing. if the bird wants lift, it changes the positioning of the primary feathers so that airflow is directed under the wing, creating higher pressure from below and therefore lift. usually, the slots work in tandem with a structural feature called camber.

camber is the teardrop shape you see when you look down the length of the wing.

the higher angle of camber, the higher severity of lift for the bird. i think i'll talk about thrust at a later date.

physics in nature is one of my favorite things to think about; physics describes the laws that govern nature, and biota evolve to fit their mold. what's REALLY COOL and MY FAVORITE THING EVER is that living things are just little balls of energy[/mass/energy]that manifest in endlessly different forms. the better an organism follows the laws of physics, the more likely it is to survive and reproduce. in the words of Biology, "form follows function."

Saturday, December 26, 2009


ratites [order struthioniformes] are basal, flightless birds. what's cool about them is that, unlike most birds, their sternum is unkeeled:
that blue bit in the picture is a keeled sternum. it's great for flight because it's a place where a lot of breast muscle can attach for lift off! but ratites don't fly, so they don't have the keeled bit. in fact, their anterior limbs hardly even exist! i think it helps them run faster. ostriches can run up to 40 mph, holy smokes!

i can't decide which ratite is my favorite, but i've narrowed it down to cassowaries and kiwis:

1. BIG
2. colorful
4. head crest
5. terrifying
1. smallest of the order
2. long, thin beak for bug eatin'
3. national symbol of New Zealand
4. largest egg-to-body ratio of ...all birds, i think. something like 42% of the bird's mass is egg.
now THAT'S commitment!


one time national geographic told me that birds are latter-day dinosaurs.

ah, tell me something i don't know.

birds are cool, more about it l8r
[2 b cntnd]