Images from iNaturalist are potentially a useful tool to collect distributional records for land snails. However, only relatively few species are identifiable on a randomly taken image. I cannot speak for other areas, but for the Neotropics many photographs will never reach the ‘research quality’ stadium and even those labelled as such are sometimes unidentifiable at species level.
Most persons seem unaware of the need to picture snails from certain directions to record characteristics that will allow other people to identify the species. It is a pity that this way many observations will never be used.
Land snails are usually either ‘flattened’ (shell diameter > shell height) or ‘elongate’ (shell height > shell diameter).
For the first type ideally 5 different views are available, like in this figure:
For elongate shells 3 views may be needed, e.g.:
Most people seem afraid to pick up shells because they think they will disturb them. When snails are crawling around, first take a few pictures of them showing the animal, if possible from different sides. The colour of the animal can help to make a distinction between similar species. Secondly pick up the snail and photograph it from different sides to show views as shown above. If the snail does not retract itself in the shell to allow a good view of the aperture shape, just touch it lightly and in most cases it will retract. Finally, when you are satisfied with your photos, put the snail back on the place where you found it; the snail may not start crawling immediately, but it will after some time.
Sometimes snails are glued to the substrate. In this case they are in hibernation and in this case you have to decide if you leave them as such (taking the risk that your images will not lead to a species identification) or that you carefully remove them from their substrate to make the different views of the shell. After finishing please place them back on the same place or a suitable place nearby; it usually means with the aperture down on the surface.
Make sure the lighting is okay and there is enough contrast with the background. It is great if something is showing that gives at least an indication of size. Fingers, a hand, or a coin are potentially useful.
A challenge will be small species especially those of < 5 mm. They may be less suitable for iNaturalist observations, especially when they are fragile. Try to image them in their natural habitat and hopefully at least a family or genus assignment can be made…
An examples from iNaturalist with comments:
Research quality and identification possible. Shows both habitat and main characteristics of the shell in multiple views; only a view from the apertural side would have been nice as addition…
Hopefully these examples give some clues about do’s and don’t’s. The core message is, if you think that a random single snapshot will give you a perfect identification, then chances are high you are mistaken. Please take a few minutes to take multiple photographs with the above suggestions in mind. Your observations will be of much more value to your fellow-nature lovers…