Signs of pregnancy in a snail vary depending on species. Some snails are egg layers and some are live-bearers. If you know your snail's species you can figure out if your snail is about to have babies by examining her and observing her behavior.
How to Tell if an Egg-Laying Snail Is Pregnant
You may be able to tell your snail is pregnant by looking in her genital tube. If the genital tube is full of eggs, you can expect her to lay a brood soon. To take a look at your snail's genital tube, hold her by the shell with her body facing you and wait for her to come out of her shell. Her genital tube is located on the left side of her body if she's facing you. The eggs will look like tiny, sticky, transparent orbs.
How to Tell if a Livebearing Snail Is Pregnant
If you have a livebearing snail like a Japanese trapdoor snail (Viviparus malleatus), the eggs will be visible in the mother snail's shell. The eggs will hatch in her shell, and the babies will remain there for the first stage of their lives. Many species of Viviparus will bury themselves in the substrate until their babies are ready to emerge from the mother's shell. If your snail has buried herself in the gravel, she's likely to be pregnant. Livebearers often reproduce only twice a year and produce small broods compared with those of egg-layers.
Hermaphroditic and Gonochoristic Snails
Whether your snail can get pregnant depends on whether she's hermaphroditic or gonochoristic. In hermaphrodite species each snail has both sets of sex organs, so two snails of this type can reproduce, or one hermaphrodite can mate with either a male or a female snail. Gonochoristic snails, or those that aren't hermaphroditic, require that one be male and one female to breed. If you own only gonochoristic female snails and no males or hermaphrodites, it's impossible for your females to get pregnant. If you have only one hermaphroditic snail, she still isn't likely to get pregnant, because very few species of snails can self-fertilize.
A Single Snail Can Be Pregnant
Female snails can store sperm in their bodies for months, so it can be difficult to predict when a snail will become pregnant after she's mated with a male. You may bring home a single female snail from the pet store and witness her lay eggs because she was fertilized before you acquired her.
Have Your Snails Been Mating?
If your snails have been mating it's almost certain a brood of eggs is on its way, as long as your snails are of the same species. Sometimes snails from different species will perform mating behaviors, but no pregnancy will result. You can tell when your snails are mating because the male will mount the female and put his penis in her genital tube. He may stay on top of her for an hour or several hours. Often snails won't mate unless tank conditions are right -- for instance apple snails usually breed when the water temperature has sharply risen and food is abundant.
- The Apple Snail Website: Reproduction
- Aqualand Fact Sheets: Caring for Your New Mystery Snail
- AquaticCommunity.com: Chinese Mystery Snail
- The Apple Snail Website: How to Recognize an Apple Snail
- petfish.net: Marisa Cornurieties - Giant Colombian Ramshorn
- The Apple Snail Website: Ecology of Apple Snails
- Animal Planet: Freshwater Snails
- Freshwater Gastropods of North America: Bellamya chinensis (Reeve 1863)
- snail egg image by bayu harsa from Fotolia.com