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whatissevenbysix t1_ityj09s wrote

Directly under the egg's shell are two membranes. When the eggs are laid by the mother they’re very warm, and as they cool the material inside the egg shrinks a little bit. The two membranes pull apart a little and create a small pocket or sack of air. As the developing bird grows, it breathes in oxygen from the air sack and exhales carbon dioxide. Several thousand microscopic pores all over the surface of the egg allow the CO2 to escape and fresh air to get in.

Full article here


Upset-Ad4844 t1_ityqz3z wrote

Great answer, but one quick correction. They are not breathing (using lungs) until they hatch, however they are respiring. I have to confess my ignorance on the exact mechanism, but the membranes seem to allow for the O2-CO2 gas exchange to the blood.


emmyarty t1_ityy5bk wrote

Another quick correction: respiration is not the biological term for gas exchange, but rather the process by which usable energy is released and made available to cells. That's why anaerobic respiration is still a form of respiration.

Breathing is still the most appropriate way to describe lungless gas exchange, whether it's fish breathing through their gills or lungless salamanders breathing cutaneously.


JennaSais t1_itziw9q wrote

Great corrections, but one more quick correction (because I want to play too!) They don't wait until they hatch to start breathing, they start breathing when they pip. That is to say, inside the shell, they break the air sac and begin to breathe, and then they make their first hole in the shell. At this stage you can often hear them making their first peeping sounds, even before they've "zipped" (which is when they start pecking a line open around the shell, and the stage at which you can typically catch your first glimpse of the emerging chick.)

I have some quail eggs I'll be setting soon, I'll try to remember to film!


jcgam t1_itzzhni wrote

It's amazing such complex behaviour is already programmed in, and they don't have to learn it.


sametrical t1_iu0056x wrote

Was disappointed that you don't also have another quick correction, but I do agree with you that it is amazing


JennaSais t1_iu05odf wrote

Right? Another fun tidbit is that the earliest chicks' peeping sounds stimulate the latecomers to work to get out as well, so you can see some very early social behaviors with them as well.


paul_wi11iams t1_iu0m3yx wrote

> you can see some very early social behaviors.

Here's a more cynical take on this:

As a chick, I'd do the same, hatching just after the first. So the first-hatched would keep any predator busy while I get out of my shell and improve my own chances of survival.

It compares to zebras running close-packed, each improving its individual chances because the lion will catch only one.

Edit: Thinking further, I concede that there could be a big overlap between social behavior and selfish gene survival. For example, the first to hatch could be helping out its siblings by offering itself up to a predator.


LandlordakaThe_Super t1_iu2a1u2 wrote

Although most predators will simply eat an egg because it does not attempt to run away.


jqbr t1_iu41q3y wrote

Spider behavior is considerably more complex than what's being described here.


ecksate t1_iu0eun0 wrote

Spectacular corrections, but one small tidbit that's barely related but does break some reasonable assumptions: human babies, at some point in development, do some amount of breathing, and what they breath in and out is amniotic fluid (just for practice, not for gas exchange.)


Omnizoom t1_iu0s1bx wrote

One extra tidbit to add , our lungs are very capable of exchanging oxygen and co2 with a liquid so even amniotic fluid would be able to do a chemical exchange


DJBscout t1_iu22iog wrote

So.....why can't I breathe water then? I wanna play fish, damnit.


Omnizoom t1_iu2n0jh wrote

Because water is a crappy source of oxygen compared to air , but if you were to breathe a oxygen rich fluid that can also absorb co2 then your body will be able to use it


who-dee-knee1 t1_iu0sxnm wrote

Amazing correction, but I have one more correction…..

Jk, I just wanted to feel included.


Da_Real_OfficialFrog t1_iu848ga wrote

One more correction actually! I don’t have a correction I just wanted to feel included


GeriatricZergling t1_itz1mza wrote

Incorrect. The term "respiration" is used for both; they're simply different enough that nobody gets confused when talking about cells vs multicellular animals exchanging gasses.


emmyarty t1_itz4iev wrote

They're both used, yes, but one is a colloquialism. A technical correction should be technically precise.


[deleted] t1_itzakhv wrote



Upset-Ad4844 t1_iu005je wrote

I stand corrected, emmy. Thank you for the correction.


RoyalAlbatross t1_itzmlbr wrote

Well “gas exchange” is a pretty straightforward phrase to use here, as you just did.


BIG_IDEA t1_iu0etkj wrote

The correct term is “diffusion.” It’s so strange that the term didn’t come up anywhere in the thread lol.


lazy_smurf t1_iu0jw1p wrote

Diffusion and respiration are both correct but from different perspectives. Diffusion is focused on the molecular movement (chemical/physical perspective) and respiration is focused on the organism's processes (biological perspective).


Ramiel01 t1_iu0a1ir wrote

So the correct term would be perfusion?


Josette22 t1_iu1p6s0 wrote

This must be what goes on with a human fetus. We don't breathe with our lungs until we're born.


cranfeckintastic t1_iu1ymg4 wrote

The blood-vessels that form inside the shell would be what absorb the oxygen and transfer it to the chick. It's the same sort of thing with reptile eggs, save they tend to have a slightly larger air pocket and, unlike bird eggs, can't be moved from the position they were laid in as it runs a high risk of smothering the air pocket and suffocating the embryo.


more_beans_mrtaggart t1_ityvejp wrote

The air sac is at the rounded end of the egg.

When boiling eggs, make a hole in the rounded end of the egg (I use a fork tine) the the bubbles will come out rather than the shell splitting apart as the cooked egg expands inside the shell.


polaarbear t1_itziimc wrote

Is this a real problem? I can't think of myself ever having an issue with eggs cracking while being hard-boiled. Seems like you've have to SEVERELY over-cook them for that to happen.


kintar1900 t1_itzlkit wrote

It even happens to me once in a blue moon, and I prefer my hard-boiled eggs slightly on the medium side so I don't think overcooking is the problem.


penny_eater t1_iu09s6s wrote

The air has to come out somewhere as it expands. Sometimes it can get out through the micropores in the egg and sometimes it can't and the shell cracks. Has nothing to do with if its overcooked at all, as the trapped air will be the very first thing to get hot during cooking.


st0p_the_q_tip t1_iu0gfn7 wrote

It happens if you put the eggs in boiling water (which makes it easier to time it, especially across different pots), not so much if you start cold


CompetitionOther7695 t1_iu21ba4 wrote

Word! I boil them without piercing the shells and they never burst, put them in the water cold, bring it to boil and then set them aside with a cover, as the water cools they cook perfectly


[deleted] t1_itzzo3c wrote



bawng t1_iu098in wrote

I usually boil mine for 8 minutes and I don't think I have ever had any of them crack.


more_beans_mrtaggart t1_iu09o4w wrote

Cracking is down to the brand of chicken and partially how much calcium is in the chicken’s diet.


poplarleaves t1_iu0dit4 wrote

Thank you, I'm going to try this next time! I've been having issues with eggs cracking when I boil them


Amaline4 t1_iu2o3m5 wrote

This is a much better explanation than the one I was going to give, which was

"through the eggxit hatch"


Neraquox t1_iu15eha wrote

So if you submerge the egg in water it can drown?


benvonpluton t1_ityl5rl wrote

Air can pass through the shell. As a matter of fact, that's why dinosaur eggs weren't much bigger than an ostrich egg even when the adults could be 30 or 40 meters long : a bigger egg would have needed a thicker shell, which would have made it impossible for the air to pass through.


Tohrchur t1_itzt2hu wrote

does that mean ostrich eggs are roughly the maximum size for an egg?


AtmaJnana t1_itzznri wrote

Ostrich eggs are not the largest known eggs. Elephant bird eggs apparently ranged up to about twice as large as the average ostrich egg.

>Dinosaur eggs vary greatly in size and shape, but even the largest dinosaur eggs (Megaloolithus) are smaller than the largest known bird eggs, which were laid by the extinct elephant bird.


perpetualwalnut t1_itzxa7i wrote

I can also imaging that as the egg size goes larger the volume increases faster than the surface area of the shell compounding the lack of oxygen problem.


burningmanonacid t1_iu0cnat wrote

Am glad to see this this far up. More than air can pass through the shell too. In Ireland, they used to use butter all over eggs to close the pores and keep them longer according to a book I read before. They could be kept for much longer than normal like that and also come out tasting kinda buttery without needing to add it.


ZairyMonkey t1_ityu9wo wrote

Oxygen and CO2 can pass through the shell. I learned this recently when hearing that one method for controlling the Canadian goose population where I live is to find the nests, distract the parents, and paint the eggs with a thin coat of cooking oil, which blocks the o2 in, co2 out process. The adults don't notice and continue caring for the eggs but they simply never hatch.


kenobismom17 t1_ityvgmg wrote

That's like next level infanticide. Smother ... let the geese keep their growing excitement for parenting.... then watch the geese be sad. What's good for the gander isn't always good for the goose.


BigCockLock t1_ityw5zs wrote

Geese do not have a growing excitement for parenthood. They act on instinct


LuneBlu t1_iu03hzf wrote

Have you asked a mother goose?


chundricles t1_iu0q5mh wrote

A survey of geese on the excitement they feel for parenting showed the following:

70% responded "squawk"

30% responded with pecking


Thog78 t1_iu1xoan wrote

And what is "growing excitement" if not an instinct ;-) ?


herrbdog t1_iu1vexi wrote

with few predators, they quickly become a nuisance

yeah, humans are to blame for that

at least we should eat them like the wolves and coyotes would have


silent_cat t1_itz4rmc wrote

And the reason they do it this way is because if you remove the eggs they just lay more.

The same things works for pigeons by the way. You get them to lay in a special nest where you simply make sure they don't hatch.

Though in this example they simply shake the eggs, which is apparently enough to prevent them hatching.


ecchi83 t1_itzhte4 wrote

I'm so tired... Am I supposed to... shake the baby?


wakka55 t1_itzzjd2 wrote

You don't have to follow the recipe - your favorite undetectable baby killing method works too


nerdguy1138 t1_iu2yqiu wrote

This works with most birds apparently. Take the eggs away, they lay more.

It's really helped bring back the falcons in NY.


[deleted] t1_ityizmo wrote



sifterandrake t1_ityrch5 wrote

Now, for the important question. If I surrounded myself in chicken eggshell, would I be able to breath? (assuming it was egg shaped, just big enough to fit my body and a reasonable air pocket.)


VictorVogel t1_ityuc13 wrote

According to google, a newborn chick weights about 38 grams. Lets assume an adult male weighs 80kg, so that's 2105 times as heavy. The third root of 2105 is 12.8, so an adult human sized egg would have sides of 12.8 times a normal egg, the surface area would be 12.8*12.8 = 163.84 times as big, and the amount of surface area per mass is roughly 12.8 times as small. It will be a lot harder for the human to breathe. This all assumes that the human egg shell is equally thick.

I'd say it is unlikely.