Oysters are alive when eaten raw.
That is unless you cook the oyster before eating them then in that case the cooked oyster would be dead and no longer alive.
But as for raw oysters they are indeed alive when you eat the oyster raw.
The reason oysters are not vegan is because the oysters are a type of animal.
Any type of animal meat is not vegan as vegans eat only plant based foods and stay away from meats.
So if a vegan eats oysters they are going against their belief in what they eat.
Oysters are not vegan, and anyone who consumes oysters is not a vegan.
This is because these bivalve molluscs are part of the biological kingdom Animalia (aka the animal kingdom).
So, just as cows, horses, dogs, birds, shark, bees and snails are animals, so too are oysters.
By definition, no, oysters are not vegan; they are still living organisms which means they can't be considered a vegan food.
Given the facts, it's not surprising that oysters draw mixed responses from vegans, but it is ultimately down to an individual whether they feel comfortable eating them.
Oysters are marine animals that are often found in brackish habitats.
They are very irregular in shape and the valves of some are highly calcified.
They belong to the phylum Mollusca.
Oysters are animals that eat algae and other food particles that are usually drawn to their gills.
Oysters are still alive as you eat them!
In fact, if you are going to eat an oyster raw, it has to be alive or else it will no longer be safe to eat.
In the case of oysters, alive means fresh!