I hope this would be pinned so people can check this first if they are wondering about the species of their snails. I thought it would be nice to have a thread with pictures, sizes and some basic stuff about different species. There are other species too, but these ones are the most common.
Let's start from the smallest ones, lake and river limpets:
Lake Limpet - Acrolocus lacustris and River Limpet Ancylus fluviatilis
Size: 1 - 8 millimetres ; 0.04 - 0.3 inches
They are both really small snails and their hood-shaped and limpet like shells don't have whorls. They aren't really limpets, but they resemble them really much. They breathe through skin and lung. They don't fill their lung with air like most of the other pulmonate snails, but they keep it filled with water. The walls of the lung sack have lots of blood wessels, that makes it easy to exchange oxygen and carbon dioxide through the walls. When the snail has used up the oxygen from the water (or air) and it is filled with carbon dioxide, the snail will release the old water and take in new.
They usually won't do much damage to plants since they are really small, but they can look really ugly if there's too many of them. If you look closely, through magnifying class, you might find these little hermaphroditic (snail has both sexes, but usually need other snails to fertilise the eggs) snails interesting.
Small Planorbids, Ramshorn Snails - Family Planorbidae
Size: 3 - 10 millimetres ; 0.1 - 0.4 inches
There's many similar species and they are hard to tell apart. The ones in the picture are most likely Gyraulys albus, white ramshorn snails. Planorbids don't have trapdoors (operculum), they have reddish body coloured by hemoglobin and their shell is flat and disc-like. Usually the shell has 3 - 4 whorls. They are hermaphroditic and lay really small egg clutches underwater, they are almost impossible to find. These ones are also pulmonate and breathe through skin and lung, but like Lake and River Limpets, they don't (at least) usually take air in their lung.
These seem to be the hardest ones to get rid of. They can reproduce like rabbits and they can do damage to live plants. There are also bigger planorbids, for example Planorbis planorbis and Planorbarius corneus.
Bladder/Tadpole/Pouch Snails - Family Physidae
Size: 9 - 15 millimetres ; 0.3 - 0.6 inches
Physa, Physella, Aplexa, Stenophysa, first two ones being the most common subfamilies. The one in the picture is most likely Physa fontinalis. Physids consists of several different species and subfamilies, they all have sinistral shells (when you keep the snail towards you and the spire pointing up, the shell lip/opening points to the left), thin tentacles and they don't usually grow over 2 centimetres/0.8 inches. They are also hermaphroditic and pulmonate, no operculum. They do take air to their lung and you can see them rising to the surface regularly. They also have two hand like mantle lobes extended against the outer side of the shell on both sides of the snail to give more area for exchange of oxygen and carbon dioxide.
Physids and Lymnaeidae snails can easily be mixed with each other, they look almost the same and act the same. They also lay same kind of eggs. Clear eggs are inside a jelly like clear clutch and the clutch is usually horseshoe shaped, might be straight too. The eggs are laid on plants, decoration and even on tank walls. You can and you should remove the eggs when you spot them. These can reproduce really fast and might do damage to live plants. Can tolerate brackish water.
Common Pond Snail - Lymnaea peregra
Size: 10 - 25 millimetres ; 0.4 - 1 inches
Common pond snail's shell shape and coloration varies alot. It has dextral (when you keep the snail towards you and the spire pointing up, the shell lip/opening points to the right) shell, 3-4 spires, dotted skin and flat, triangular tentacles. When Physidae's feet end pointed, Lymnaeidae's feet end rounder and they are shorter.
Both Lymnaeidae and Physidae are hermaphroditic and it is said that a single snail can even fertilise itself if it doesn't find a mate. Pond snails grow larger than Physids and seem to be more easily controlled. They are also way slower than Physidd, the F1 version of snails. Can tolerate brackish water.
There is also Great Pond Snail - Lymnaea stagnalis, it can grow to 2 inches and has usually plain brown shell.
Snail eggs (L. stagnalis, but these are similar to other pond snails and Physids)
Malaysian Trumpet Snail - Melanoides tuberculata
Size: 15 - 30 millimetres ; 0.6 - 1.2 inches
Shell is conical, 5 -> spires, they have operculum, heart shaped mouth and thin tentacles. Malaysian trumpet snails, MTS, are really useful snails. They eat algae and leftover fish food (also dead fish and fish eggs),dead plant material and they will usually leave live plants alone. They burrow in the sand during daytime unless there are too many snails or the substrate is too compacted and going bad. They will help with keeping the sand loose. When the lights are off the snails head towards the surface and start eating algae.
They give birth to live babies and are usually all females and they reproduce through parthenogenesis (females don't need to be fertilised).
Great Ramshorn Snail - Planorbarius corneus
Size: 20 - 30 millimetres ; 0.8 - 1.2 inches
Great ramshorn snail is also a planorbid and the largest species I know. It has hemoglobine in its blood and it's shell is disc-like. It is bigger and it lays visible egg clutches which are also disc-shaped and impossible to scrape off without breaking the clutch. 3-4 spires, the shell is more reddish when the snail is young, it might even have dots. When the snail gets older, the shell darkens and might turn almost olive green.
There are other species almost like great ramshorn snail, for example Planorbis planorbis which stays smaller, but acts alike.
Since they are big, it is easier to maintain reasonable population. The eggs are also fairly visible. They can eat plants, but might not if you give them enough boiled vegetables.
Zebra Snail - Neritina natalensis
Size: 20 - 30 millimetres ; 0.8 - 1.2 inches
Thick shell is drop-like shaped and colourful with stripes. Thin tentacles and dark body, small operculum. The shell consists almost solely from the last spire, usually the first spires have been broken apart already when they arrive to stores. They eat algae like a dream and wont usually touch live plants. They have separate sexes and females lay hard, white eggs on glass and other hard surfaces, they are almost impossible to scrape off. It is really difficult to get eggs to hatch and even more difficult to get hatched larvae to develop and grow.
Zebra snails need a tight lid on their tank, they tend to climb off regularly.
Trapdoor Snails - family Viviparidae
Size: 25 - 40 millimetres ; 1 - 1.2 inches
Viviparidae, Campelominae, Bellamynae. Trapdoor snails look a bit like apple snails, and also have an operculum (also called a trapdoor). The shell has an extended spire with 4-5 whorls. They are coldwater snails, prefering temperatures between 65 and 75 degrees Fahreinheit (18-24C). Water warmer than this accelerates their metabolism too much and they will have a greatly shortened lifespan. They don't usually eat plants, and in the wild spend a lot of time burrowed in the substrate. Viviparids are sometimes called mystery snails, as are apple snails, though the two are not closely related. Viviparids are live-bearers that reproduce fairly slowly, so their population can be easily controlled in an aquarium.
Viviparids are actually the original snail referred to as a "mystery snail" because of the fact that they are live-bearers, and so baby snails would appear "mysteriously". The name "mystery snail" was later applied incorrectly to apple snails due to aquarists' confusion regarding the two types of snails.
Giant Ramshorn Snail - Marisa cornuarietis
Size: 20 - 30 millimetres ; 0.8 - 1.2 inches
Marisa cornuarietis is a beautiful, flat shelled apple snail with 3-4 whorls, it has an operculum like other apple snails. Shell coloration varies from yellow to brown with or without brown/black spiral bands, there is almost white variety too. They eat live plants and small pest snails. They have separate sexes and the egg clutches are laid below the water surface. They don't seem to climb over the water surface and might be kept in a tank without coverplate.
Marisa eggs:
Apple Snail - Pomacea bridgesii
Size: 40-60 millimeters, 1.5-2.5 inches
Shell with 5-6 whorls and a long spire. The sutures between the whorls are almost 90°, giving the shell a "stepped" appearance. This apple snail is usually bought as a pet and isn't considered a pest in the aquarium trade. Pomacea bridgesii doesn't usually eat plants and might even starve to death in a planted tank if there isn't any food. They eat all kinds of fish foods (flakes, freeze-dried, forzen, pellets, granules...), and soft vegetables (boiled peas, zucchini, lettuce, etc.). As is true with all apple snails, if the pH is under 7.0, the shell will start to erode. Extra calcium in the water will be beneficial to their shell growth and thickness. Pomacea bridgesii's temperature range is 18-28°C (65-82°F), with an optimum range of 70-80°F. They lay their egg clutches above the waterline. In humid and warm conditions the egg clutch will hatch in 2-4 weeks. The babies are small and they will eat the same foods as the adults, but preferably in smaller pieces.
Apple snails have both a lung and a gill, so they can get oxygen both directly from the air and from the water. Water flows through the gill and apple snails take air into the lung with their siphon, which works like a snorkel. They periodically climb to the surface of the water and extend their siphon to breath. This involves pumping the head in and out of the shell to make the lung expand and contract, forcing air in and out of the lung. Apple snails tend to climb above the waterline often and that's why there needs to be a coverplate on the tank. They do survive for days out of water, but they might break their shells if they fall to the ground, running into a child or cat/dog/ferret wouldn't be a good idea either from the snails point of view.
There are several color variations of apple snails, purple, blue, ivory, golden, jade... And the colours don't come from the food or dye, they really are natural, just selectively bred from wild color variation, like different colours on bettas.
Pomacea bridgesii shell:
Apple Snail - Pomacea
Size: 40 - 110 millimetres ; 1.6 - 4 inches
There are many other apple snail species in genus Pomacea, and there are also others from the genera (the family is Ampulariidae) Afropomus, Asolene, Felipponea, Lanistes, Pila, Saulea, and Marisa. Most of the other ones available in stores than P. bridgesii aren't suitable for planted tanks (Pomacea canaliculata and Marisa cornuarietis), but they are still really interesting species. If you think you have regular apple snail but it eats plants, you most likely have P. canaliculata. If you have an apple snail that is closer to 4 inches, you might have P. insularum or P. haustrum.
More information about apple snails and other snails can be found here: http
/www.applesnail.net/. I suggest you read that site thoroughly if you are interested in snails. There is everything you need to know and more. From Various-section you will find a page about other freshwater snails and a good guide to tell them apart. This is also an excellent site which contains information about apple snail colours and health problems: Apple Snail Research - Donya Quick.
Snails can be really useful in aquariums, you just need to know which species you have and if you need to get rid of some and maybe even get more of some. Remember, snails can be friends and above all, they are fascinating and beautiful.
Let's start from the smallest ones, lake and river limpets:
Lake Limpet - Acrolocus lacustris and River Limpet Ancylus fluviatilis
Size: 1 - 8 millimetres ; 0.04 - 0.3 inches
They are both really small snails and their hood-shaped and limpet like shells don't have whorls. They aren't really limpets, but they resemble them really much. They breathe through skin and lung. They don't fill their lung with air like most of the other pulmonate snails, but they keep it filled with water. The walls of the lung sack have lots of blood wessels, that makes it easy to exchange oxygen and carbon dioxide through the walls. When the snail has used up the oxygen from the water (or air) and it is filled with carbon dioxide, the snail will release the old water and take in new.
They usually won't do much damage to plants since they are really small, but they can look really ugly if there's too many of them. If you look closely, through magnifying class, you might find these little hermaphroditic (snail has both sexes, but usually need other snails to fertilise the eggs) snails interesting.
Small Planorbids, Ramshorn Snails - Family Planorbidae
Size: 3 - 10 millimetres ; 0.1 - 0.4 inches
There's many similar species and they are hard to tell apart. The ones in the picture are most likely Gyraulys albus, white ramshorn snails. Planorbids don't have trapdoors (operculum), they have reddish body coloured by hemoglobin and their shell is flat and disc-like. Usually the shell has 3 - 4 whorls. They are hermaphroditic and lay really small egg clutches underwater, they are almost impossible to find. These ones are also pulmonate and breathe through skin and lung, but like Lake and River Limpets, they don't (at least) usually take air in their lung.
These seem to be the hardest ones to get rid of. They can reproduce like rabbits and they can do damage to live plants. There are also bigger planorbids, for example Planorbis planorbis and Planorbarius corneus.
Bladder/Tadpole/Pouch Snails - Family Physidae
Size: 9 - 15 millimetres ; 0.3 - 0.6 inches
Physa, Physella, Aplexa, Stenophysa, first two ones being the most common subfamilies. The one in the picture is most likely Physa fontinalis. Physids consists of several different species and subfamilies, they all have sinistral shells (when you keep the snail towards you and the spire pointing up, the shell lip/opening points to the left), thin tentacles and they don't usually grow over 2 centimetres/0.8 inches. They are also hermaphroditic and pulmonate, no operculum. They do take air to their lung and you can see them rising to the surface regularly. They also have two hand like mantle lobes extended against the outer side of the shell on both sides of the snail to give more area for exchange of oxygen and carbon dioxide.
Physids and Lymnaeidae snails can easily be mixed with each other, they look almost the same and act the same. They also lay same kind of eggs. Clear eggs are inside a jelly like clear clutch and the clutch is usually horseshoe shaped, might be straight too. The eggs are laid on plants, decoration and even on tank walls. You can and you should remove the eggs when you spot them. These can reproduce really fast and might do damage to live plants. Can tolerate brackish water.
Common Pond Snail - Lymnaea peregra
Size: 10 - 25 millimetres ; 0.4 - 1 inches
Common pond snail's shell shape and coloration varies alot. It has dextral (when you keep the snail towards you and the spire pointing up, the shell lip/opening points to the right) shell, 3-4 spires, dotted skin and flat, triangular tentacles. When Physidae's feet end pointed, Lymnaeidae's feet end rounder and they are shorter.
Both Lymnaeidae and Physidae are hermaphroditic and it is said that a single snail can even fertilise itself if it doesn't find a mate. Pond snails grow larger than Physids and seem to be more easily controlled. They are also way slower than Physidd, the F1 version of snails. Can tolerate brackish water.
There is also Great Pond Snail - Lymnaea stagnalis, it can grow to 2 inches and has usually plain brown shell.
Snail eggs (L. stagnalis, but these are similar to other pond snails and Physids)
Malaysian Trumpet Snail - Melanoides tuberculata
Size: 15 - 30 millimetres ; 0.6 - 1.2 inches
Shell is conical, 5 -> spires, they have operculum, heart shaped mouth and thin tentacles. Malaysian trumpet snails, MTS, are really useful snails. They eat algae and leftover fish food (also dead fish and fish eggs),dead plant material and they will usually leave live plants alone. They burrow in the sand during daytime unless there are too many snails or the substrate is too compacted and going bad. They will help with keeping the sand loose. When the lights are off the snails head towards the surface and start eating algae.
They give birth to live babies and are usually all females and they reproduce through parthenogenesis (females don't need to be fertilised).
Great Ramshorn Snail - Planorbarius corneus
Size: 20 - 30 millimetres ; 0.8 - 1.2 inches
Great ramshorn snail is also a planorbid and the largest species I know. It has hemoglobine in its blood and it's shell is disc-like. It is bigger and it lays visible egg clutches which are also disc-shaped and impossible to scrape off without breaking the clutch. 3-4 spires, the shell is more reddish when the snail is young, it might even have dots. When the snail gets older, the shell darkens and might turn almost olive green.
There are other species almost like great ramshorn snail, for example Planorbis planorbis which stays smaller, but acts alike.
Since they are big, it is easier to maintain reasonable population. The eggs are also fairly visible. They can eat plants, but might not if you give them enough boiled vegetables.
Zebra Snail - Neritina natalensis
Size: 20 - 30 millimetres ; 0.8 - 1.2 inches
Thick shell is drop-like shaped and colourful with stripes. Thin tentacles and dark body, small operculum. The shell consists almost solely from the last spire, usually the first spires have been broken apart already when they arrive to stores. They eat algae like a dream and wont usually touch live plants. They have separate sexes and females lay hard, white eggs on glass and other hard surfaces, they are almost impossible to scrape off. It is really difficult to get eggs to hatch and even more difficult to get hatched larvae to develop and grow.
Zebra snails need a tight lid on their tank, they tend to climb off regularly.
Trapdoor Snails - family Viviparidae
Size: 25 - 40 millimetres ; 1 - 1.2 inches
Viviparidae, Campelominae, Bellamynae. Trapdoor snails look a bit like apple snails, and also have an operculum (also called a trapdoor). The shell has an extended spire with 4-5 whorls. They are coldwater snails, prefering temperatures between 65 and 75 degrees Fahreinheit (18-24C). Water warmer than this accelerates their metabolism too much and they will have a greatly shortened lifespan. They don't usually eat plants, and in the wild spend a lot of time burrowed in the substrate. Viviparids are sometimes called mystery snails, as are apple snails, though the two are not closely related. Viviparids are live-bearers that reproduce fairly slowly, so their population can be easily controlled in an aquarium.
Viviparids are actually the original snail referred to as a "mystery snail" because of the fact that they are live-bearers, and so baby snails would appear "mysteriously". The name "mystery snail" was later applied incorrectly to apple snails due to aquarists' confusion regarding the two types of snails.
Giant Ramshorn Snail - Marisa cornuarietis
Size: 20 - 30 millimetres ; 0.8 - 1.2 inches
Marisa cornuarietis is a beautiful, flat shelled apple snail with 3-4 whorls, it has an operculum like other apple snails. Shell coloration varies from yellow to brown with or without brown/black spiral bands, there is almost white variety too. They eat live plants and small pest snails. They have separate sexes and the egg clutches are laid below the water surface. They don't seem to climb over the water surface and might be kept in a tank without coverplate.
Marisa eggs:
Apple Snail - Pomacea bridgesii
Size: 40-60 millimeters, 1.5-2.5 inches
Shell with 5-6 whorls and a long spire. The sutures between the whorls are almost 90°, giving the shell a "stepped" appearance. This apple snail is usually bought as a pet and isn't considered a pest in the aquarium trade. Pomacea bridgesii doesn't usually eat plants and might even starve to death in a planted tank if there isn't any food. They eat all kinds of fish foods (flakes, freeze-dried, forzen, pellets, granules...), and soft vegetables (boiled peas, zucchini, lettuce, etc.). As is true with all apple snails, if the pH is under 7.0, the shell will start to erode. Extra calcium in the water will be beneficial to their shell growth and thickness. Pomacea bridgesii's temperature range is 18-28°C (65-82°F), with an optimum range of 70-80°F. They lay their egg clutches above the waterline. In humid and warm conditions the egg clutch will hatch in 2-4 weeks. The babies are small and they will eat the same foods as the adults, but preferably in smaller pieces.
Apple snails have both a lung and a gill, so they can get oxygen both directly from the air and from the water. Water flows through the gill and apple snails take air into the lung with their siphon, which works like a snorkel. They periodically climb to the surface of the water and extend their siphon to breath. This involves pumping the head in and out of the shell to make the lung expand and contract, forcing air in and out of the lung. Apple snails tend to climb above the waterline often and that's why there needs to be a coverplate on the tank. They do survive for days out of water, but they might break their shells if they fall to the ground, running into a child or cat/dog/ferret wouldn't be a good idea either from the snails point of view.
There are several color variations of apple snails, purple, blue, ivory, golden, jade... And the colours don't come from the food or dye, they really are natural, just selectively bred from wild color variation, like different colours on bettas.
Pomacea bridgesii shell:
Apple Snail - Pomacea
Size: 40 - 110 millimetres ; 1.6 - 4 inches
There are many other apple snail species in genus Pomacea, and there are also others from the genera (the family is Ampulariidae) Afropomus, Asolene, Felipponea, Lanistes, Pila, Saulea, and Marisa. Most of the other ones available in stores than P. bridgesii aren't suitable for planted tanks (Pomacea canaliculata and Marisa cornuarietis), but they are still really interesting species. If you think you have regular apple snail but it eats plants, you most likely have P. canaliculata. If you have an apple snail that is closer to 4 inches, you might have P. insularum or P. haustrum.
More information about apple snails and other snails can be found here: http
/www.applesnail.net/. I suggest you read that site thoroughly if you are interested in snails. There is everything you need to know and more. From Various-section you will find a page about other freshwater snails and a good guide to tell them apart. This is also an excellent site which contains information about apple snail colours and health problems: Apple Snail Research - Donya Quick.Snails can be really useful in aquariums, you just need to know which species you have and if you need to get rid of some and maybe even get more of some. Remember, snails can be friends and above all, they are fascinating and beautiful.
What do you think of those?
Anything else? 
