First checkIs it a single shell — coiled, or a low cone in a limpet — with a foot rather than a head with legs coming out of it?
A single shell with a soft foot gliding out of it is one of the few things in this guide that is hard to confuse once you have it in your hand. The shell is usually coiled; a freshwater limpet's is a low cone.UMW-AQUATIC-INVERTS, EPA-MACROINVERT-FIELD-GUIDEDispute
The confusion happens before that, on the rock: a cased caddis is a tube of glued grit and can read as a shell at arm's length. Pick it up. If a jointed head and legs come out of the front, it is an insect that built a case. If a soft muscular foot comes out and grips your finger, it is a snail.Dispute
This entry stops at 'snail'. The gilled and lunged families really do differ, and the difference is a horny trapdoor on the foot that closes the shell when the animal withdraws, on a shell that may be a centimetre across. That is not a call to make on a bank, so this guide does not offer it.MDC-GILLED-SNAILSDispute
The tell
What settles it, and what settles against it.
Read off this record's own diagnostic weights, heaviest first. A structure near the top of the left column does most of the work on its own; one near the bottom only leans.
Argues for Freshwater snail
A single coiled shell with a soft foot coming out of it+7
Aquatic insect crawling on rock or debris+3
Argues against it
Two hinged shell halves that close on the animal-6
Fish-shaped forage silhouette (minnow / shiner / fry) — not an insect-5
Moving as a school or tight bait cluster, not as a single insect-4
A structure at −4 or below is treated as a hard exclusion by the comparison tool rather than as a penalty: if you saw it, this group is ruled out and no amount of matching elsewhere brings it back. Run a comparison →
Life stages
What it looks like, stage by stage.
Freshwater snail — Every stage — juveniles are the same animal, smallerdrawn
Every stage — juveniles are the same animal, smaller
A soft muscular foot extended from the shell mouthDispute
No legs, no antennae of the jointed kind, no head capsuleDispute
Where it turns up
Grazing on rock, wood and plant stems. In Missouri, gilled snails dominate only in the Ozarks' well-oxygenated streams and spring branches; lunged snails predominate elsewhere.MDC-GILLED-SNAILS, MDC-LUNGED-SNAILSEvidence from: MissouriDispute
How it moves
A slow glide on the foot. Many pulmonates climb to the surface to take air, which briefly puts them in the film.MDC-LUNGED-SNAILSDispute
Cues this stage offers the comparison
A single coiled shell with a soft foot coming out of it
Aquatic insect crawling on rock or debris
Confused with
Telling it from what it isn't.
Freshwater snailvsClam (small freshwater bivalve)
One shell or two. A snail's shell is a single coil; a clam is two hinged halves that close on the animal.
Where in the column it mattersNear the bottom. Grazing on hard surfaces most of the time, but a lunged snail climbing for air genuinely does reach the film — the one band an angler can see into, and the one place a snail is briefly available.
Read from the record's own position notes: grazing on rock, wood and plant stems; many pulmonates come up to the film to take air.
What eats it
Which fish the dossiers actually name.
No reviewed dossier names this group. That is an absence in the dossier layer rather than a finding about the animal — four dossiers exist and only one of them names any forage group at all.
Nothing in the pattern layer is mapped to this group, so no presentation family follows from it here.
Not known
What this entry cannot tell you.
9 of them. The limits are part of what was reviewed rather than a disclaimer bolted on afterwards. An entry that hid them would be claiming more than it checked.
Written by the reviewer
Declared by the reviewer'Snail' and no finer. This guide does not attempt the gilled/lunged split, because the character that decides it, the operculum, is hard to see on a small shell.MDC-GILLED-SNAILSDispute
Declared by the reviewerIt cannot tell a native snail from an invasive one — a New Zealand mudsnail is usually only 4 to 6 mm long in the Great Lakes.USGS-NAS-NZ-MUDSNAILEvidence from: Great LakesDispute
Declared by the reviewerSnails have no emergence, so nothing here carries timing information of any kind.Dispute
Declared by the reviewerThis is 'snail' and nothing finer. The gilled/lunged split turns mainly on an operculum, a small horny trapdoor on the foot that is hard to see on a shell half an inch across, so this record does not attempt it.MDC-GILLED-SNAILS, MDC-LUNGED-SNAILSDispute
Declared by the reviewerIt cannot tell a native snail from an invasive one. The New Zealand mudsnail, for example, is usually only 4 to 6 mm long in the Great Lakes.USGS-NAS-NZ-MUDSNAILEvidence from: Great LakesDispute
Declared by the reviewerSnails have no emergence, so this record carries no timing information at all.Dispute
Read off the record
Nobody typed these. They are fields that are empty, said out loud rather than left for you to notice from a section that simply is not there.
SeasonalityNo reference window is published for this group, so this entry says nothing about when it is available. That is an absence in the calendar layer, not a claim that the animal has no season.
PatternsNo fly pattern in the pattern layer is mapped to this group. Whether anything imitates it is not answered here.
What eats itNo reviewed species dossier names this group. Some dossiers describe forage in class terms — small forage, insects, bait — and those are shown below, but a class description is not a reviewed link to this group and none is claimed.
Sources
Everything above rests on 7 published pages.
These are every page behind this entry. Where a reviewer traced a line above to the pages that carry it, that line names them itself, with where the evidence comes from when it is narrower than the whole entry. A line with no names beside it rests on this list as a whole: nobody has yet checked which page carried it, and naming one would be a mapping nobody made.
A plate shows shape. It cannot show a gill beating, a mask firing, or an animal reversing into sand — so where motion is the field mark, the entry points at motion. These are demonstrations, selected by hand and by publisher. Nothing here is a source: it changes no score, no window and no reviewed claim.
Leaf Pack Network. A snail gliding on an extended muscular foot with the shell trailing, which is how you tell one from a cased caddis in a tray.
Research institute · external video · title read back from the publisher 2026-09-09
Carry it on
Take the group to the next step.
These send the class of animal and the water this record is documented in. They do not send a sighting, because this page does not have one — you have not told it what you saw.
Which fish in this kind of water are documented eating this class of forage, and how they behave when they are.
What this forage class asks of the setup — the weight it wants, and where the chain gives first.
Keep the group on the day's record, so a later entry can be compared against what you were looking at.
Found an error?
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