# Which animal is the best at processing its food? **URL:** \ **Category:** Factual Questions\ **Created:** [January 12, 2003, 1:42am UTC](https://boards.straightdope.com/t/which-animal-is-the-best-at-processing-its-food/148059 "2003-01-12T01:42:27Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Mr.Blue\_Sky](https://avatars.discourse-cdn.com/v4/letter/m/d26b3c/32.png) [@Mr.Blue\_Sky](https://boards.straightdope.com/u/Mr.Blue_Sky)\ **Post date:** [January 12, 2003, 1:42am UTC](https://boards.straightdope.com/t/which-animal-is-the-best-at-processing-its-food/148059/1 "2003-01-12T01:42:27Z")
There have questions before about which foods are most efficiently processed (that is, produces the least amount of waste), but which has the most efficient digestive system? ---
**Author:** ![mightyaphrodite](https://avatars.discourse-cdn.com/v4/letter/m/47e85d/32.png) [@mightyaphrodite](https://boards.straightdope.com/u/mightyaphrodite)\ **Post date:** [January 12, 2003, 2:15am UTC](https://boards.straightdope.com/t/which-animal-is-the-best-at-processing-its-food/148059/2 "2003-01-12T02:15:24Z")
> [@](#): > > \*Originally posted by Mr. Blue Sky \* > \*\*There have questions before about which foods are most efficiently processed (that is, produces the least amount of waste), but which has the most efficient digestive system? \*\* Good question. I haven’t heard anything to that regard yet, though I know birds have the most efficient respiratory system and the Kangaroo Rat has the most efficient kidney. ---
**Author:** ![Nishroch\_Order](https://avatars.discourse-cdn.com/v4/letter/n/b4bc9f/32.png) [@Nishroch\_Order](https://boards.straightdope.com/u/Nishroch_Order)\ **Post date:** [January 12, 2003, 2:22am UTC](https://boards.straightdope.com/t/which-animal-is-the-best-at-processing-its-food/148059/3 "2003-01-12T02:22:01Z")
WAG: first thing that came to my mind is the humming bird. I have no stats or figures but judging from what the eat(nectar), and how they need so much energy to stay “humming”…i’ll say they are pretty much more efficient in utilizing their diet then other animals… ---
**Author:** ![pravnik](https://avatars.discourse-cdn.com/v4/letter/p/8edcca/32.png) [@pravnik](https://boards.straightdope.com/u/pravnik)\ **Post date:** [January 12, 2003, 2:24am UTC](https://boards.straightdope.com/t/which-animal-is-the-best-at-processing-its-food/148059/4 "2003-01-12T02:24:00Z")
If by “efficient” you mean “least waste” (and I’m not sure you do), Hydras digest food intracellularly instead of extracellularly like we do, which I think results in complete digestion. ---
**Author:** ![Anomalocaris](https://avatars.discourse-cdn.com/v4/letter/a/b77776/32.png) [@Anomalocaris](https://boards.straightdope.com/u/Anomalocaris)\ **Post date:** [January 12, 2003, 5:02am UTC](https://boards.straightdope.com/t/which-animal-is-the-best-at-processing-its-food/148059/5 "2003-01-12T05:02:18Z")
For a college physiology class, a friend and I measured the digestive efficiency of a boa constrictor. We determined how much feces corresponded with a single feeding (one mouse) and measured how many calories was in the feces. By comparing this with the amount of calories in an average-sized mouse, we determined that the boa’s digestion was so efficient, it extracted enough calories from a single meal to support it for nearly a year. The snake’s stomach expands after swallowing it’s prey whole, and it floods with HCl. It can digest bones and cartilage; only hair and occasionaly teeth remain undigested. Most likely snakes are the most efficient digesters among the vertebrates. ---
**Author:** ![Speaker\_for\_the\_Dead](https://avatars.discourse-cdn.com/v4/letter/s/c77e96/32.png) [@Speaker\_for\_the\_Dead](https://boards.straightdope.com/u/Speaker_for_the_Dead)\ **Post date:** [January 12, 2003, 5:21am UTC](https://boards.straightdope.com/t/which-animal-is-the-best-at-processing-its-food/148059/6 "2003-01-12T05:21:02Z")
Wouldn’t you have to burn the feces to determine its calorie content? :eek: ---
**Author:** ![Anomalocaris](https://avatars.discourse-cdn.com/v4/letter/a/b77776/32.png) [@Anomalocaris](https://boards.straightdope.com/u/Anomalocaris)\ **Post date:** [January 12, 2003, 5:29am UTC](https://boards.straightdope.com/t/which-animal-is-the-best-at-processing-its-food/148059/7 "2003-01-12T05:29:19Z")
Yes, Speaker. We dried both the feces and a dead mouse in a drying oven for 24h, then we burned them in a bomb calorimeter. For the record, a mouse has about as many calories as a McDonald’s hamburger patty. ---
**Author:** ![Lodrain](https://avatars.discourse-cdn.com/v4/letter/l/c4cdca/32.png) [@Lodrain](https://boards.straightdope.com/u/Lodrain)\ **Post date:** [January 12, 2003, 5:50am UTC](https://boards.straightdope.com/t/which-animal-is-the-best-at-processing-its-food/148059/8 "2003-01-12T05:50:38Z")
> [@](#): > > \*Originally posted by Anomalocaris \* > \*\*Yes, Speaker. We dried both the feces and a dead mouse in a drying oven for 24h, then we burned them in a bomb calorimeter. For the record, a mouse has about as many calories as a McDonald’s hamburger patty. \*\* I never knew that. Fascinating. A Big Mac is… how big? And a mouse… I’d think a Big Mac’d contain _more_ calories, being the fatty, greasy bag of empty calories and death fat it is. But no, a dried mouse is more likely to destroy my New Year’s resolution than two all-beef patties. Weird. By the way, love your username. ---
**Author:** ![Anomalocaris](https://avatars.discourse-cdn.com/v4/letter/a/b77776/32.png) [@Anomalocaris](https://boards.straightdope.com/u/Anomalocaris)\ **Post date:** [January 12, 2003, 6:11am UTC](https://boards.straightdope.com/t/which-animal-is-the-best-at-processing-its-food/148059/9 "2003-01-12T06:11:11Z")
Actually, Lodrain, the mouse’s caloric equivalent is just the patty. A Big Mac contains two patties, plus the bun, cheese, and the mysterious Secret Sauce which must contribute untold calories to the product. So dried mice are a viable dietary alternative to Big Macs, and all that fur is likely to contribute to a sense of fullness (much like fiber.) ---
**Author:** ![Slip\_Mahoney](https://avatars.discourse-cdn.com/v4/letter/s/e47774/32.png) [@Slip\_Mahoney](https://boards.straightdope.com/u/Slip_Mahoney)\ **Post date:** [January 12, 2003, 7:09am UTC](https://boards.straightdope.com/t/which-animal-is-the-best-at-processing-its-food/148059/10 "2003-01-12T07:09:17Z")
Okay, I’m convinced. What’s the best way to cook a mouse? ---
**Author:** ![Cisco](https://avatars.discourse-cdn.com/v4/letter/c/ccd318/32.png) [@Cisco](https://boards.straightdope.com/u/Cisco)\ **Post date:** [January 12, 2003, 7:34am UTC](https://boards.straightdope.com/t/which-animal-is-the-best-at-processing-its-food/148059/11 "2003-01-12T07:34:25Z")
> [@](#): > > \*Originally posted by pravnik \* > \*\*Hydras digest food intracellularly instead of extracellularly like we do, which I think results in complete digestion. \*\* Isn’t a Hydra a mythological serpant that grows two heads for every one you cut off? 😕 ---
**Author:** ![pravnik](https://avatars.discourse-cdn.com/v4/letter/p/8edcca/32.png) [@pravnik](https://boards.straightdope.com/u/pravnik)\ **Post date:** [January 12, 2003, 8:45am UTC](https://boards.straightdope.com/t/which-animal-is-the-best-at-processing-its-food/148059/12 "2003-01-12T08:45:25Z")
Yep. But a hydra is also a small carnivorous freshwater coelenterate (an invertebrate from the Greek “hollow gut”). Basically, they’re just small elogated polyps with tentacles and mouths. I’m guessing the name comes from their habit of asexual budding, but I dunno. ---
**Author:** ![Urban\_Ranger](https://avatars.discourse-cdn.com/v4/letter/u/e9c0ed/32.png) [@Urban\_Ranger](https://boards.straightdope.com/u/Urban_Ranger)\ **Post date:** [January 12, 2003, 9:25am UTC](https://boards.straightdope.com/t/which-animal-is-the-best-at-processing-its-food/148059/13 "2003-01-12T09:25:02Z")
I think it is named after the mythical multi-headed creature. ---
**Author:** ![Ruffian](https://avatars.discourse-cdn.com/v4/letter/r/71e660/32.png) [@Ruffian](https://boards.straightdope.com/u/Ruffian)\ **Post date:** [January 12, 2003, 3:38pm UTC](https://boards.straightdope.com/t/which-animal-is-the-best-at-processing-its-food/148059/14 "2003-01-12T15:38:02Z")
The first thing I think of is a constricting snake (boas, pythons, corn snakes). They digest everything from the hair to the enamel on the teeth. Unlike owls, who urp up the hair, bones, and other indigestibles, snake poo is just a dark brown mass with a smattering of white (urine). Considering such a meal will sate their hunger for a number of weeks, I consider that quite efficient. ---
**Author:** ![Bosda\_Di\_Chi\_of\_Tricor](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bosda_di_chi_of_tricor/32/16845_2.png) [@Bosda\_Di\_Chi\_of\_Tricor](https://boards.straightdope.com/u/Bosda_Di_Chi_of_Tricor)\ **Post date:** [January 12, 2003, 5:11pm UTC](https://boards.straightdope.com/t/which-animal-is-the-best-at-processing-its-food/148059/15 "2003-01-12T17:11:22Z")
Bees convert necter and pollen into honey, which is merely digested food–a.k.a bee vomit. [http://www.straightdope.com/classics/a5\_040.html](http://www.straightdope.com/classics/a5_040.html) But bees get a _lot_ of flying out of that stuff. So, they’re probably good candidates for the title. Also, the remarks pertaining to honeybees near the bottom of the article here: [http://www.straightdope.com/mailbag/mwarmblood.html](http://www.straightdope.com/mailbag/mwarmblood.html) bespeak of a remarkable metabolism. ---
**Author:** ![Mr.Blue\_Sky](https://avatars.discourse-cdn.com/v4/letter/m/d26b3c/32.png) [@Mr.Blue\_Sky](https://boards.straightdope.com/u/Mr.Blue_Sky)\ **Post date:** [January 13, 2003, 2:58am UTC](https://boards.straightdope.com/t/which-animal-is-the-best-at-processing-its-food/148059/16 "2003-01-13T02:58:42Z")
Thanks for the input so far. I recall seeing a nature documentary about owls. The owl would catch and eat a mouse and, after a few daays, cough up a ball of undigestible matter - hair, bone, etc. Would this put them in line with the above mentioned snakes? ---
**Author:** ![Anomalocaris](https://avatars.discourse-cdn.com/v4/letter/a/b77776/32.png) [@Anomalocaris](https://boards.straightdope.com/u/Anomalocaris)\ **Post date:** [January 13, 2003, 4:57am UTC](https://boards.straightdope.com/t/which-animal-is-the-best-at-processing-its-food/148059/17 "2003-01-13T04:57:20Z")
Owls are efficient, but it seems snakes have them beat. Owls generally don’t digest bones or teeth, as anyone who pulled apart an owl pellet in high school can tell. But they leave behind little else, so they are near the top. ---
**Author:** ![Blake](https://avatars.discourse-cdn.com/v4/letter/b/a9a28c/32.png) [@Blake](https://boards.straightdope.com/u/Blake)\ **Post date:** [January 13, 2003, 6:30am UTC](https://boards.straightdope.com/t/which-animal-is-the-best-at-processing-its-food/148059/18 "2003-01-13T06:30:28Z")
In believe the question is going to be impossible to answer. Efficiency is normally defined as 1/net input - net output. As such it’s going to depend on diet as much as the animal. AFAIK all animals are 100% efficient at digesting pure glucose. If you feed a hydra 100% glucose solution it will digest it at 100% efficiency. If you feed a the toed sloth 100% glucose solution it will digest it at 100% efficiency. Ditto for people, snakes and hairy nosed wombats. That’s the technical answer to the OP as stated: all animals are 100 efficient. People seem to be answering the question as it relates to the animal’s ‘normal’ diet by talking about snakes, hummingbirds and so on. The question then becomes ‘what animals has the most efficient digestive system at processing its normal food?’. That question is going to be very hard to answer because ‘normal’ varies so much. Animals that live on easily digestible substances like sugars or highly digestible proteins would rate very highly, so the hummingbirds, moths etc would al be in the running, along with chupacabras. Snakes, because they leave so much food behind as hair and bone wouldn’t be as efficient as mammalian carnivores that are a bit more selective about avoiding indigestible bits. Digestive efficiency doesn’t however normally depend on efficiency at digesting food, since that is so close to meaningless. Instead it normally translates to the proportion of material converted to body weight. Generally speaking the ‘cold blooded’ animals are the best at this, since so little energy is wasted maintaining unnecessary body temperature. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [January 13, 2003, 10:28am UTC](https://boards.straightdope.com/t/which-animal-is-the-best-at-processing-its-food/148059/19 "2003-01-13T10:28:41Z")
Are there not parasites that lack a developed digestive system; absorbing **only** the required nutrients directly from the host? ---
**Author:** ![Blake](https://avatars.discourse-cdn.com/v4/letter/b/a9a28c/32.png) [@Blake](https://boards.straightdope.com/u/Blake)\ **Post date:** [January 13, 2003, 11:05am UTC](https://boards.straightdope.com/t/which-animal-is-the-best-at-processing-its-food/148059/20 "2003-01-13T11:05:26Z")
Yeah, most parasitic flatworms, but you’re pushing the definition of digestion if there is no digestive system, and no chemical or physical breakdown. [Next page](https://boards.straightdope.com/t/which-animal-is-the-best-at-processing-its-food/148059.md?page=2)