Are there any fully vegetarian animals?

This simple question occurred to me while being sent out to get various items for vegetarian and vegan humans.

Cows and sheep might initially appear to be vegetarian but they might actually eat whatever is in front of them including the odd mouse/vole as well as all the invertebrates on the vegetation.

So trying to think of other animals that might be more definitely vegetarian or at least only eat the invertebrates intimately associated with the leaves etc that they are consuming. Perhaps sloths on the assumption that the slower the eating the more likely any (live) animal is to escape from the jaws.

Perhaps something specialist like a koala? I think they may eat a small number of leaves other than eucalyptus but not sure they would intentionally eat anything else.

I’d expect that in the process of eating eucalyptus leaves koalas consume aphids and other phytophagous insects.

For a fully vegetarian animal (in the broader sense) I’d look for something like a leaf mining caterpillar, though even those might consume smaller invertebrates that cross their path.

There’s also the question of how strictly one defines fully vegetarian (abstaining from meat, or only consuming plants? do algae count as plants?); does one exclude sciarid flies because they mostly eat fungi.

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I hadn’t realised that Koalas eat cyanide!

I was fortunate enough to spot a wild one in South Australia many years ago.

Lucky you Ken! Did you get any pictures - if so you should do a post. It would fit in with Dejay’s Earth awareness project given the threats they are facing

Sadly, no photos. I only had a small compact camera with me on that trip (we’re talking film, not digital in those far-off days).
As an aside, If anyone watches ‘I’m a celebrity’, I can tell you from personal experience that those Australian green ants really are very nippy. I only got bitten once and it was very painful.