Suggestion: Teach learners to use "fressen" exclusively in sentences containing animals.
This would probably be very easy to implement. There are plenty of sentences in the beginning of the German from English course in which "essen" is used with animals. An example is "Der Hund isst einen Vogel." Although I have been informed that this sentence is correct, it is most certainly less common. We should push to get learners on track to making this distinction early on. Thanks guys.
While some people might make such a strict distinction, I would not necessarily agree. To me, "essen" is a more general term just describing the intake of (solid) nutrition, which can be - and often is - used not only for humans, but also other animals. "Fressen" on the other hand sounds more ferocious. It usually (but not always) implies a fast and rather wild way of eating. For non-human animals it is therefore mainly used synonymously to "essen" (or as "essen" is being used for humans). It can also be used for humans, where it usually (but again not always) is used when you try to express your discontent with someone else's way of eating, implying that they should pay more attention to proper etiquette (it can be used as an insult then, too).
So I would not call a sentence like "Der Hund isst einen Vogel." wrong and don't think that duolingo should necessarily change it, although a comment could be nice.
You make a great point, but I have never heard anyone say "essen" with a non-human before. I'm not a native speaker, but I spent a good amount of time in Berlin with many native speakers. Maybe more speakers could chime in here with their opinions. Even if the sentence is right, I doubt it is very common. Although it is correct for me to say "I masticate my salad happily," I wouldn't teach it to a learner of English as if it were the way to say I'm chewing.
Well, I as a native speaker use it quite often. But you are probably right that more people would use "fressen" in this context. Why I think that it is not such a big deal in this case, however, is because - unlike in your example with "masticate" and "chewing" - "essen" is the overall much more common word and as such should be already known by the learner. "Fressen" would be one additional word you have to learn, while "essen" is easily understood if you use it in place of "fressen". Although I suppose that since "fressen" is literally just "essen" with two additional letters in front it might not be that much extra work after all.
So maybe duolingo could change it (or as I said, make a comment about it), but I still maintain that the usage of "essen" should be acceptable. Duolingo should therefore not give the impression that it is wrong, i.e. it should be accepted as correct in my opinion, even if they would change the suggested translation (in the case of translating from English to German).
Not sure about the downvotes. jjd1123 is perfectly right. Although "fressen" is definitely more common, there is nothing wrong with using "essen" for animals. It's completely fine, just less common. [Native speaker]
But I agree that it would make more sense for Duolingo to teach "fressen" with animal subjects.
A bit offtopic:
The English cognate of "fressen" is "to fret".
"Etwas in sich hineinfressen" = "to suppress ones (negative) feelings"
"der Fraß" = disgusting food, e.g. "Was ist das für ein Fraß? Das kann man nicht essen!"
Das Gesetz der Natur: Fressen und gefressen werden.
"Das große Fressen" - "La grande bouffe", a famous film with Marcello Mastroianni: http://en.wikipedia.org/wiki/La_Grande_Bouffe
What a wonderful word.
EDIT: Some more:
"Ein gefundenes Fressen" - "an easy prey"
"Die Fresse" - "the mouth (pejorative), la gueule"
"Jemandem die Fresse polieren" - "to smash somebody's face"
(Don't use the last two expressions in polite society.)
"Ich fresse einen Besen, wenn ..." - "I eat my hat, if ..."
"verfressen, gefräßig" - "gluttonous"
Die großen Fische fressen die kleinen.
Fressen is related to the English term "frass", which is a term used for bug poop.
I believe there is an analogous word for drinking... saufen?
Interestingly (but not surprisingly), there used to be the same distinction in Old English. etan vs fretan and I don't remember the verbs for drinking. They were used when speaking of animals and monsters (those in Beowulf, for example).
Unlike "fressen", which is for all animals (by the way: using "essen" for animals is just wrong), you would use "saufen" mainly for big animals: horses, oxen, pigs and such. For smaller and cuter animals you use "trinken" in fact. The borderline might be animals the size of a dog:
Die Mücke trinkt einen Tropfen Wasser (Do they do this? Well, we are about language, not biology.)
Die Katze trinkt ihre Milch.
Die Hyäne säuft an der Wasserstelle.
Der Bulle säuft aus seinem Trog.
Yes, "saufen" is used for animals. If applied to humans it normally refers to alcoholism. A "Säufer" is a person who drinks too much alcohol...
Yes, it's the past participle of the reflexive verb sich besaufen = drink too much alcohol.
For me betrinken and besaufen are essentially interchangeable. I have never practised this myself, so for me it's all the same. But besaufen does sound more extreme as saufen tends to involve more liquid than trinken. (This is essentially the distinction that Radebrech described in terms of animal sizes.)
Basically, "essen" is for humans only. For all other animals, "fressen" is used. Instead of "Der Hund isst einen Vogel," you would say "Der Hund frisst einen Vogel." It conjugates the same with fr- in front.
Edit - You can see below that jjd1123 uses "essen" with animals as a native speaker, so it may not be wrong, but only less common.
Ach so!!! I had noticed that the verb 'fressen' is used in the German-French course but assumed it was a synonym. Danke!
Not to mention the "ich esse das Mittagessen" sentences that make my eyes go round. I'm pretty sure nobody ever says that. Isn't It: "ich esse zu Mittag" a better option? Just pointing out something obvious but... It's something we must know.
While there is nothing wrong with "Ich esse das Mittagessen." per se, you are both correct that it is not really used in place of the simpler "Ich esse zu Mittag."
The first one might make sense if you want to emphasise that you are eating your lunch instead of e.g. throwing it away. This might more commonly occur in a question like "Isst du dein Mittagessen noch?" (Are you finishing your lunch?"), though.
This formulation is even required when you are eating your lunch in the evening because you prepared it for noon but didn't have the time to eat it then.
I agree. I also noticed that in the French from German course (in the German sentences, the French ones are fine).
As far as I can tell, and I have seen a lot of it, the French from German course always uses essen or fressen where appropriate though it also accepts essen for animals, as it should. For users who already speak German and want to learn French, this is exactly what is required.