It IS kinda confusing as some websites say they are the same species and other sites say NO, they are 2 different species. It drove me NUTS when I was trying to identify what I snagged out of a local lake...
all I know is my store bought snail is big and black...
I have also seen it somewhere online that certain types of apple snails are not allowed to be imported as they are not native to local waters - ot sure where it was though
if you bought your animal from a pet shop, you probably have a Pomacea diffusa apple snail or a snail from the Pomacea canaliculata - insularum group. The latter is a group of very similar and closely related species. In most cases, the offered snail is a Pomacea insularum or a Pomacea canaliculata snail, but occasionally Pomacea haustrum and possibly other species from the canaliculata group, like Pomacea maculata might be available as well.
For the snails of the Pomacea canaliculata - insularum group, it's quite hard to distinguish the species as the external differences are subtle and the variation within species is high. A possible way do distinguish these snails is the colour of the eggs*. one should also keep in mind that hybrids between several closely related species might occur. This cannot be ruled out in invasive species and those available in the aquarium trade.
SpeciesEgg colourOther notes Pomacea (pomacea) canaliculata (Lamarck, 1819) Bright orange Pomacea (pomacea) insularum (D'Orbigny, 1839) Pink Pomacea (pomacea) lineata (Spix, 1827) Pink Pomacea (pomacea) doliodes (Reeve, 1856) Pink Pomacea (pomacea) haustrum (Reeve, 1856) Green Pomacea (pomacea) gigas / maculata (Perry, 1810) Green grows over 10cm / 4 inch
* This is based on reported egg colours, and it could well be that even the egg colour varies withing one species. Also the food composition, the development stage of the eggs and the humidity of the air can affect the egg colour.
When the snail has a flat shell and has a size over 2.5 cm (1 inch) with or without dark stripes, you are the owner of a Marisa cornuarietis apple snail (Giant ramshorn snail). This snail is not always recognized as an apple snail due to its different appearance.
Less common, but also occasionally available in the aquarium trade (mainly in the US) is Pomacea paludosa (Florida apple snail).
Below is a quick and dirty guide to identify them based on the shape of the shell. Once more: Ignore the colour of your snails when you try to determine the species by comparing them with pictures. Many colour variations (shell and body) exist within a single species (see photograph on the right) and in the 'Colour genes' section. Pomacea diffusa): flat shoulders and 90° sutures (scalariform).
The flat shoulder, however, becomes less apparent in the last whorls of the shell. Pomacea bridgesii is not known to be available in the aquarium trade. Pomacea canaliculata and Pomacea insularum: indented sutures, less than 90°angle.
This shell is more globose (rounder) than the Pomacea diffusa shell. Pomacea paludosa: Almost flat sutures with an over 90° angle, which gives the snail a cone shaped shell top (spine). Pomacea haustrum and Pomacea insularum: Deeply indented sutures with a sharp shoulders.
To make identification somewhat easier, these 3D-models of snail shells are included. One can rotate this virtual shells in any direction with the mouse cursor. Interactive 3D-models (Java):
- Asolene megastoma shell
- Marisa cornuarietis shell
- Pila ampullacea shell
- Pila brohadri shell
- Pomacea diffusa shell
- Pomacea canaliculata shell
- Male Pomacea flagellata flagellata shell
- Female Pomacea ***ellata flagellata shell
Sometimes other apple snail species pop-up in the trade, mostly imported species. In these cases, it can be quite difficult to identify them. Try to find out from which region they come as this makes identification much easier.
If you need help to identify an apple snail: feel free to contact me and take some pictures of the snail in such way that the following thing are visible: shell opening (aperture), whole shell shape (including the top), the umbilicus (or measure the size), the sutures of the shell and if available the shell door (operculum). Also measure the size of the shell and if available describe if the operculum is horny (flexible) or calcified.
Have a look at the Pomacea flagellata section to see how a useful picture of the shell looks like.