If you have tropical fish and look closely at top of glass of your tank (above water level), you’ll occasionally see small, orange things in clusters. They’re jelly-like blobs that might lead you to believe something is wrong with your water quality or maybe even that a parasite has moved in. In reality, it’s much less scary.
Those are eggs of the mystery snail. Where they lay them is an intentional evolutionary decision. To understand why, one must look at survival strategy of these gastropods.
For mystery snails, it’s all about having your cake and eating it too, in this case, having both aquatic and terrestrial habitat works for them. Nature is good at solving its own problems: how to survive predation and how to avoid drying out. The placement of the clutch above water isn’t accidental, it’s protective and deliberate.
Why Mystery Snails Lay Eggs Above Water
Identifying Mystery Snail Eggs
This isn’t so much about aesthetics but rather it’s all about predator protection, specifically eggs. Because we have a bunch of indiscriminate, hungry fish in our tanks, anything that look like food to a fish is fair game. Small, gelatinous blobs are just that to the majority of tropical fish.
Protection From Fish Predators
If there are eggs below surface of water, they’ll be eaten by goldfish, tetras, small cichlid, etc. To prevent that, the momma snail simply puts her eggs where those water hunters can’t get to them. The water becomes a barrier and that’s a good way to stop most frequent threat found in most tanks. And that’s because they’re air breathers.
The mystery snail is a type of pulmonate gastropod. That means it have lungs (well, at least it has a lung-like cavity). They don’t have to get all their oxygen from the water, they can come up for some air.
Air Breathing And Egg Moisture
And when they do, they don’t drown, they’re able to go above surface tension. That’s how they were able to spawn in places where other more water-loving snails couldn’t. If it didn’t had lungs, it wouldn’t make it back up there.
The eggs have resistance to drying out. When you think about it, being exposed to the air should of mean they’ll shrivel up into little dried out embryos. Nope.
A natural sealant forms around outside of egg mass. It allows for gas exchange but holds in moisture. The jelly encloses a moist environment where developing embryos can thrive.
Even if the air around them is dry, the structure keep the eggs moist. It’s like a biological humidity dome. Putting the eggs underwater would create other problems.
Defense Against Fungal Infections
Fungal and bacterial infections from water are more easily transmitted to these exposed embryos than those in air. Even if tightly held in place, water movement in a filtered tank will knock loose any loosely adhered egg clutch. Eggs placed above the surface is stationary and protected.
They are less likely to be disturbed by powerful currents or nibbled by foraging shrimp. It is not without cost to the snail, who must expend energy getting up there and positioning the eggs. But it’s worth it because the eggs’ viability outweighs the effort.
In nature, the strategy that results in the highest number of live offspring win out. Also, temperature stability matter. Room changes and heater failures cause fluctuations in water temps.
Temperature Stability For Development
In a controlled room, air temps over the tank tend to be more stable. This consistency help the eggs throughout the critical development periods. Sudden temp changes can stall embryo development or even shock the developing egg.
That air pocket buffer the eggs from rapid thermal change in the water. A stable temperature helps with consistent hatching. Early on, it’s not always about being warmer than as much as it is about consistency.
This alters how you manage your tank. When you notice the egg clusters, you know they’re there. It is okay, though.
Managing Egg Clusters In Tanks
There is nothing wrong with them and they are perfectly healthy. Now you decide whether or not you want to remove them if you want to control the population. Or you let them go.
Either way, they’ll eventually hatch within a week or two. At that time, tiny snail will fall into the water column. No need to interfere.
Simply stand back and watch as it happens. These eggs wait patiently out-of-reach, waiting for their time. It is a lesson in how even simplest of creature make complex plans to survive.
