# Gestation Period of External Egg **URL:** \ **Category:** Factual Questions\ **Created:** [April 18, 2007, 7:33am UTC](https://boards.straightdope.com/t/gestation-period-of-external-egg/400591 "2007-04-18T07:33:47Z")\ **Posts on this page:** 9\ **Page:** 1
**Author:** ![Darryl\_Lict](https://avatars.discourse-cdn.com/v4/letter/d/7cd45c/32.png) [@Darryl\_Lict](https://boards.straightdope.com/u/Darryl_Lict)\ **Post date:** [April 18, 2007, 7:33am UTC](https://boards.straightdope.com/t/gestation-period-of-external-egg/400591/1 "2007-04-18T07:33:47Z")
I was wondering what the name is for the gestation period of an egg laid outside of the body. The other question is what is the longest gestation period for an external egg (not counting eggs that can survive dessication such as Brine Shrimp). From this (my) [thread](http://boards.straightdope.com/sdmb/showthread.php?t=416476) Colibri mentioned that he’d seen a Tuatara (takes a year for the egg to hatch). It’s a crazy reptile living in New Zealand and has survived for 200 million years. Quoting this [site](http://www.terranature.org/tuatara.htm) > [@](#): > > An unusual feature is a third pineal eye which has a retina and a rudimentary lens, and is connected to the brain by a nerve. It is apparent in infants, but is covered by opaque scales in adults, so it is unknown whether the eye serves any function. > > Females only mate every four years, but males wish to mate every year, which causes frustration, and considerable fighting amongst the males for partners. Eggs take four years to develop in the female, which is longer than any reptile. As many as 19 eggs are laid in a shallow depression in the ground outside the burrow, and take a full year to hatch. The gender of the hatchling is determined by the temperature of the ground. Tuatara live for 60 to 100 years. Pretty cool animal! ---
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [April 18, 2007, 11:32am UTC](https://boards.straightdope.com/t/gestation-period-of-external-egg/400591/2 "2007-04-18T11:32:27Z")
I’m no expert but coincidentally about 5 minutes ago I was trying to find out the gestation period for an egg INSIDE the body, i.e. the interval from fertilization to laying. When I Googled for [gestation period robin] or [gestation period eagle] I got lots of info answering YOUR question, and none answering mine. So it appears the term for gestation period of eggs outside the body is “gestation period.” As to duration, it varies by species, but 20-30 days seems average for typical small US birds. I have no clue about the longest. [hijack]Does anyone know the rght term for the inside-the-body time interval I’m seeking?[/hijack] ---
**Author:** ![Nava](https://avatars.discourse-cdn.com/v4/letter/n/da6949/32.png) [@Nava](https://boards.straightdope.com/u/Nava)\ **Post date:** [April 18, 2007, 11:42am UTC](https://boards.straightdope.com/t/gestation-period-of-external-egg/400591/3 "2007-04-18T11:42:01Z")
“gestational period horse” brought up 10+ pages on the gestation period of horses… seems to be the right term. [/hijack] ---
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [April 18, 2007, 12:23pm UTC](https://boards.straightdope.com/t/gestation-period-of-external-egg/400591/4 "2007-04-18T12:23:44Z")
[QUOTE=Nava] “gestational period horse” brought up 10+ pages on the gestation period of horses… seems to be the right term. [/hijack] [/QUOTE] [hijack continues …]Yes, for a mammal, that term means the time interval from fertilization to birth. But for an egg-laying creature, there are two periods, fertilization to laying & laying to hatching. “Gestation period” appears to mean the second period. I’m looking for the first. [/hijack continues …] ---
**Author:** ![vetbridge](https://avatars.discourse-cdn.com/v4/letter/v/b5e925/32.png) [@vetbridge](https://boards.straightdope.com/u/vetbridge)\ **Post date:** [April 18, 2007, 2:44pm UTC](https://boards.straightdope.com/t/gestation-period-of-external-egg/400591/5 "2007-04-18T14:44:18Z")
Incubation, I believe. ---
**Author:** ![Darryl\_Lict](https://avatars.discourse-cdn.com/v4/letter/d/7cd45c/32.png) [@Darryl\_Lict](https://boards.straightdope.com/u/Darryl_Lict)\ **Post date:** [April 19, 2007, 3:55am UTC](https://boards.straightdope.com/t/gestation-period-of-external-egg/400591/6 "2007-04-19T03:55:23Z")
[QUOTE=vetbridge] Incubation, I believe. [/QUOTE] Thanks, that works. I think I should have known that. Anyone know what the record incubation period is? ---
**Author:** ![John\_Carter\_of\_Mars](https://avatars.discourse-cdn.com/v4/letter/j/2bfe46/32.png) [@John\_Carter\_of\_Mars](https://boards.straightdope.com/u/John_Carter_of_Mars)\ **Post date:** [April 19, 2007, 5:36am UTC](https://boards.straightdope.com/t/gestation-period-of-external-egg/400591/7 "2007-04-19T05:36:15Z")
> [@LSL Guy](#): > > …But for an egg-laying creature, there are two periods, fertilization to laying & laying to hatching. “Gestation period” appears to mean the second period. I’m looking for the first. I think you’ve got that backwards? “Gestation” would be the first period. [QUOTE=vetbridge] Incubation, I believe. [/QUOTE] Indeed. And it’s even possible to purchase an incubator to keep the eggs at the proper temperature and humidity for successful hatching. Incubators are most handy if you don’t have a mama hen or you don’t want, say, Mama Crocodile watching crocodile eggs in the yard for you. ---
**Author:** ![Blake](https://avatars.discourse-cdn.com/v4/letter/b/a9a28c/32.png) [@Blake](https://boards.straightdope.com/u/Blake)\ **Post date:** [April 19, 2007, 10:16am UTC](https://boards.straightdope.com/t/gestation-period-of-external-egg/400591/8 "2007-04-19T10:16:47Z")
[QUOTE=Darryl Lict] Anyone know what the record incubation period is? [/QUOTE] There are numerous invertebrates that have eggs that require very specific environmental condirions to hatch and that can last decades and (more dipsutably) centuries. Many parasites for example will lie dormant as an egg until swallowed by an appropriate host, while many of the smaller crustaceans produce eggs will remain dormant in sediment for decades. The last I heard about this was an article in New Scientist which said the undisputed record holder was the crustacean _Daphnia_ which had been recovered from sediments over 50 years old, but that the apparent recovery of viable roundworm eggs from naturally mummified carcasses millenia old was a new record. A Google search on [Daphnia eggs dormant] reveals that collectionof viable eggs from sediment \>30 years is routine. A search on _Ascaris_ suggests that dormancy in soil of 7 years is routine. I don’t know about eggs, but with seeds once you start talking about annual time periods then usually the limiting factors are causes of death, rather than any intrinsic limitation. IOW if the egg is kept in ideal conditions and isn’t eaten, infected etc. it would probably last forever. ---
**Author:** ![vetbridge](https://avatars.discourse-cdn.com/v4/letter/v/b5e925/32.png) [@vetbridge](https://boards.straightdope.com/u/vetbridge)\ **Post date:** [April 19, 2007, 2:30pm UTC](https://boards.straightdope.com/t/gestation-period-of-external-egg/400591/9 "2007-04-19T14:30:25Z")
[QUOTE=John Carter of Mars] Indeed. And it’s even possible to purchase an incubator to keep the eggs at the proper temperature and humidity for successful hatching. Incubators are most handy if you don’t have a mama hen or you don’t want, say, Mama Crocodile watching crocodile eggs in the yard for you. [/QUOTE] Yep, and some of the incubators with automatic turning, digital readout, etc are pretty costly. I am currently using a brooder (for the period of time after hatching but before fledging) to raise a Gouldian Finch. Brooder: [![](https://i153.photobucket.com/albums/s218/vetbridge/dayoldgould3.jpg) ](https://i153.photobucket.com/albums/s218/vetbridge/dayoldgould3.jpg) “Hot Chick”: [![](https://i153.photobucket.com/albums/s218/vetbridge/dayoldgould2.jpg) ](https://i153.photobucket.com/albums/s218/vetbridge/dayoldgould2.jpg) [![](https://i153.photobucket.com/albums/s218/vetbridge/dayoldgould.jpg) ](https://i153.photobucket.com/albums/s218/vetbridge/dayoldgould.jpg) Incubation of this species is about 16 days.