# Question about how walruses feed **URL:** \ **Category:** Factual Questions\ **Created:** [March 21, 2011, 3:35am UTC](https://boards.straightdope.com/t/question-about-how-walruses-feed/575432 "2011-03-21T03:35:23Z")\ **Posts on this page:** 15\ **Page:** 1
**Author:** ![astro](https://avatars.discourse-cdn.com/v4/letter/a/9dc877/32.png) [@astro](https://boards.straightdope.com/u/astro)\ **Post date:** [March 21, 2011, 3:35am UTC](https://boards.straightdope.com/t/question-about-how-walruses-feed/575432/1 "2011-03-21T03:35:23Z")
In looking at the [walrus wiki](http://en.wikipedia.org/wiki/Walrus) it says. > [@](#): > > The walrus has a diverse and opportunistic diet, feeding on more than 60 genera of marine organisms including shrimp, crabs, tube worms, soft corals, tunicates, sea cucumbers, various mollusks, and even parts of other pinnipeds.[34] However, it prefers benthic bivalve mollusks, especially clams, for which it forages by grazing along the sea bottom, searching and identifying prey with its sensitive vibrissae and clearing the murky bottoms with jets of water and active flipper movements.[35] The walrus sucks the meat out by sealing its powerful lips to the organism and withdrawing its tongue, piston-like, rapidly into its mouth, creating a vacuum. The walrus palate is uniquely vaulted, enabling effective suction. Raw oysters are usually pretty tightly sealed and it requires a knife and deft hand to crack open the shell to get at the meat. I’m not clear on how a walrus is manipulating a clam into position with his mouth, forcing the shell open, then producing enough suction just with tongue action to pull the clam out. Is there some movie or diagram showing how this works? ---
**Author:** ![wevets](https://avatars.discourse-cdn.com/v4/letter/w/e9a140/32.png) [@wevets](https://boards.straightdope.com/u/wevets)\ **Post date:** [March 21, 2011, 4:27am UTC](https://boards.straightdope.com/t/question-about-how-walruses-feed/575432/2 "2011-03-21T04:27:36Z")
The trick is that you want to know what’s going on inside the walrus’ mouth as it’s feeding. It’s really hard to get **external** images of walruses feeding in the wild - you can watch videos from a 2003 paper here: [http://www.ncbi.nlm.nih.gov/pmc/articles/PMC270045/](http://www.ncbi.nlm.nih.gov/pmc/articles/PMC270045/) (scroll down to supplementary material for 3 videos.) - you can see how little information one might get from such videos if these are some good ones. It’s easier to get external videos in captivity, but it still won’t show what happens inside the walrus’ mouth, and I don’t know of an animation that might show it. But I think you’re discounting the amount of crushing walruses do as they feed - it’s not like they will daintily suck only the flesh out without touching the shell, they most likely are crushing the shells to some extent, and feeding on molluscs smaller than what you might be thinking; a common size for a prey mollusc might be 1-4 ounces. Remember that walruses are large mammals, and can probably apply many hundreds or thousands of pounds of force with their jaws. I did a Google Video search for “walrus feeding mollusc” and didn’t find anything useful. I doubt “mollusk” will return better results, but it might be worth a try. ---
**Author:** ![astro](https://avatars.discourse-cdn.com/v4/letter/a/9dc877/32.png) [@astro](https://boards.straightdope.com/u/astro)\ **Post date:** [March 21, 2011, 4:43am UTC](https://boards.straightdope.com/t/question-about-how-walruses-feed/575432/3 "2011-03-21T04:43:33Z")
> [@wevets](#): > > The trick is that you want to know what’s going on inside the walrus’ mouth as it’s feeding. > > It’s really hard to get **external** images of walruses feeding in the wild - you can watch videos from a 2003 paper here: [Feeding behaviour of free-ranging walruses with notes on apparent dextrality of flipper use - PMC](http://www.ncbi.nlm.nih.gov/pmc/articles/PMC270045/) (scroll down to supplementary material for 3 videos.) - you can see how little information one might get from such videos if these are some good ones. > It’s easier to get external videos in captivity, but it still won’t show what happens inside the walrus’ mouth, and I don’t know of an animation that might show it. > But I think you’re discounting the amount of crushing walruses do as they feed - it’s not like they will daintily suck only the flesh out without touching the shell, they most likely are crushing the shells to some extent, and feeding on molluscs smaller than what you might be thinking; a common size for a prey mollusc might be 1-4 ounces. Remember that walruses are large mammals, and can probably apply many hundreds or thousands of pounds of force with their jaws. > > I did a Google Video search for “walrus feeding mollusc” and didn’t find anything useful. I doubt “mollusk” will return better results, but it might be worth a try. Thanks for the link. I’m surprised in the paper that the precise mechanics of how locates food is still open to competing theories, you’d have thought that some enterprising marine biologist PHD would have laid it all out by now. ---
**Author:** ![Autolycus](https://avatars.discourse-cdn.com/v4/letter/a/22d042/32.png) [@Autolycus](https://boards.straightdope.com/u/Autolycus)\ **Post date:** [March 21, 2011, 6:42am UTC](https://boards.straightdope.com/t/question-about-how-walruses-feed/575432/4 "2011-03-21T06:42:16Z")
As everyone knows, walruses use a bucket to eat: [http://ihasabucket.com/](http://ihasabucket.com/) ---
**Author:** ![Meurglys](https://avatars.discourse-cdn.com/v4/letter/m/258eb7/32.png) [@Meurglys](https://boards.straightdope.com/u/Meurglys)\ **Post date:** [March 21, 2011, 12:45pm UTC](https://boards.straightdope.com/t/question-about-how-walruses-feed/575432/5 "2011-03-21T12:45:28Z")
[This page](http://animals.howstuffworks.com/mammals/walrus2.htm) on how a walrus works has some relevant information… Says thay can suck holes in plywood! ---
**Author:** ![CalMeacham](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/calmeacham/32/35_2.png) [@CalMeacham](https://boards.straightdope.com/u/CalMeacham)\ **Post date:** [March 21, 2011, 12:54pm UTC](https://boards.straightdope.com/t/question-about-how-walruses-feed/575432/6 "2011-03-21T12:54:13Z")
There’s potential here for a superlative comment on someone’s Oral Communication skills. Only I’ll bet most women wouldn’t want to be compared to a Walrus. ---
**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:** [March 21, 2011, 1:17pm UTC](https://boards.straightdope.com/t/question-about-how-walruses-feed/575432/7 "2011-03-21T13:17:43Z")
Less than an hour to get a good answer complete with references & videos to a question about the inside of feeding walrus’s mouths. Gotta love the Dope. Bravo **wevets**. ---
**Author:** ![astro](https://avatars.discourse-cdn.com/v4/letter/a/9dc877/32.png) [@astro](https://boards.straightdope.com/u/astro)\ **Post date:** [March 21, 2011, 10:00pm UTC](https://boards.straightdope.com/t/question-about-how-walruses-feed/575432/8 "2011-03-21T22:00:35Z")
Appreciate the responses but I’m still not clear on the process. If (per the documentation) walruses are eating 3000 to 6000 clams at a time over a few hours of feeding there’s no way each clam is being individually positioned by the mouthparts for suction extraction. There’s just no time. ---
**Author:** ![Inigo\_Montoya](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/inigo_montoya/32/124_2.png) [@Inigo\_Montoya](https://boards.straightdope.com/u/Inigo_Montoya)\ **Post date:** [March 21, 2011, 10:57pm UTC](https://boards.straightdope.com/t/question-about-how-walruses-feed/575432/9 "2011-03-21T22:57:13Z")
> [@Autolycus](#): > > As everyone knows, walruses use a bucket to eat: > > [http://ihasabucket.com/](http://ihasabucket.com/) Ho Lee Shit! Tell me walrusses aren’t really that huge! ---
**Author:** ![gazpacho](https://avatars.discourse-cdn.com/v4/letter/g/6f9a4e/32.png) [@gazpacho](https://boards.straightdope.com/u/gazpacho)\ **Post date:** [March 21, 2011, 11:05pm UTC](https://boards.straightdope.com/t/question-about-how-walruses-feed/575432/10 "2011-03-21T23:05:29Z")
> [@Inigo\_Montoya](#): > > Ho Lee Shit! Tell me walrusses aren’t really that huge! I am pretty sure that is a sea lion with the bucket. Walruses are bigger. ---
**Author:** ![Punoqllads](https://avatars.discourse-cdn.com/v4/letter/p/d2c977/32.png) [@Punoqllads](https://boards.straightdope.com/u/Punoqllads)\ **Post date:** [March 21, 2011, 11:40pm UTC](https://boards.straightdope.com/t/question-about-how-walruses-feed/575432/11 "2011-03-21T23:40:46Z")
> [@Inigo\_Montoya](#): > > Ho Lee Shit! Tell me walrusses aren’t really that huge! > [@gazpacho](#): > > I am pretty sure that is a sea lion with the bucket. Walruses are bigger. No external ears means it’s not a sea lion. No tusks means it’s not a walrus. I know that elephant seals can get that large. ---
**Author:** ![Ruken](https://avatars.discourse-cdn.com/v4/letter/r/f475e1/32.png) [@Ruken](https://boards.straightdope.com/u/Ruken)\ **Post date:** [March 22, 2011, 1:42am UTC](https://boards.straightdope.com/t/question-about-how-walruses-feed/575432/12 "2011-03-22T01:42:28Z")
> [@Punoqllads](#): > > No external ears means it’s not a sea lion. No tusks means it’s not a walrus. I know that elephant seals can get that large. According to [knowyourmeme.com](http://knowyourmeme.com/memes/lolrus) on the lolrus: "Typically a walrus who has lost a bucket, is searching for a bucket, or is enjoying a recently found bucket of some kind. PROTIP: lolrus is not actually a walrus — he was an incredibly obese seal named Minazo who passed away in 2008 at the ripe old age of 11 (pic) May he find his bukkit in heaven." ---
**Author:** ![wevets](https://avatars.discourse-cdn.com/v4/letter/w/e9a140/32.png) [@wevets](https://boards.straightdope.com/u/wevets)\ **Post date:** [March 22, 2011, 1:45pm UTC](https://boards.straightdope.com/t/question-about-how-walruses-feed/575432/13 "2011-03-22T13:45:17Z")
> [@astro](#): > > Appreciate the responses but I’m still not clear on the process. If (per the documentation) walruses are eating 3000 to 6000 clams at a time over a few hours of feeding there’s no way each clam is being individually positioned by the mouthparts for suction extraction. There’s just no time. I understand. In general, this isn’t a subject about which very much is known. To give you an idea of how sketchy knowledge in general on what goes on inside a walrus’ mouth is, perhaps the best available information on this comes from a 1991 paper with results based on a mere 2 (yes, two) walrus skulls: [http://www.aquaticmammalsjournal.org/share/AquaticMammalsIssueArchives/1991/Aquatic\_Mammals\_17\_3/Kastelein.pdf](http://www.aquaticmammalsjournal.org/share/AquaticMammalsIssueArchives/1991/Aquatic_Mammals_17_3/Kastelein.pdf) > [@Kastelein et al.](#): > > If the Walrus’ prey is a bivalve mollusk, it is moved into such a position that the siphon or foot is directed towards the pharynx. This is probably achieved by cooperation between the vibrissae, the upper lip (_M. caninus & M. dilatator narcs, M. orbicular oris_ and _M. septo-labialis_), the lower lip (_M. mentalis_) and the tip of the tongue. Then the clam is held tightly between the lower (by the _M. mentalis_) and upper lip (by the _M. caninus_ and _M. orbicular oris_). The tongue, which is shaped to closely fit the shape of the mouth cavity by the intrinsic tongue muscles (_M. lingualis proprius_), is forcefully retracted by the _M. styloglossus_ and _M. hyoglossus_ and the infrahyoidal muscles. This creates a negative pressure in the buccal cavity. Fay (1982) reports a negative pressure of -76 cm Hg in a Walrus’ mouth cavity and compared this feeding system to a vacuum pump in which the tongue works like a piston. The flexible and muscular lips ensure that the full effect of the vacuum is exerted only on objects held in the incisive area at the front of the mouth. > > … > > Because the Walrus consumes a large quantity of clams per day, the feeding actions described have to be performed very fast and very often. On one occasion, Oliver _et al._ (1983) recorded a speed of 6 clams per minute while Born & Knutsen (1990) found 6401 individual prey in a Walrus stomach. From Kastelein et al. 1991. The anatomy of the Walrus head. _Aquatic Mammals_ v. 17.3, pages 178-179. I’m not really enough of an anatomist to judge how accurately this paper may reflect reality, but briefly summarized, the Walrus traps clams with the siphon inwards at its lips using both whiskers and lip muscles. Using the tongue like a suction pump, it can suck out the meat. It seems to do so in about 10 seconds, which is not inconsistent (although it is quite an achievement! and probably represents an unusual amount of feeding time) with feeding on 6000 clams in a day, since such an effort would take about 17 hours. There are photos and diagrams in the linked paper - but the scanned photos are none too useful, you might be able to Interlibrary loan the paper to get a better look, but I hope they help. ETA: I should probably also mention this is likely not as clean a process as when humans eat clams. Walruses are likely to accept a certain amount of shell with the meat, probably more so than humans would. ---
**Author:** ![Meurglys](https://avatars.discourse-cdn.com/v4/letter/m/258eb7/32.png) [@Meurglys](https://boards.straightdope.com/u/Meurglys)\ **Post date:** [March 23, 2011, 1:05pm UTC](https://boards.straightdope.com/t/question-about-how-walruses-feed/575432/14 "2011-03-23T13:05:56Z")
Of course, if you know [Morse](http://encyclopedia.jrank.org/VIR_WAT/WALRUS_or_MORSE_Odobaenus_rosma.html) code, you can ask one yourself! 😉 ---
**Author:** ![wevets](https://avatars.discourse-cdn.com/v4/letter/w/e9a140/32.png) [@wevets](https://boards.straightdope.com/u/wevets)\ **Post date:** [March 23, 2011, 8:53pm UTC](https://boards.straightdope.com/t/question-about-how-walruses-feed/575432/15 "2011-03-23T20:53:07Z")
> [@LSLGuy](#): > > Less than an hour to get a good answer complete with references & videos to a question about the inside of feeding walrus’s mouths. > > Gotta love the Dope. > > Bravo **wevets**. Thanks, LSLGuy!