Apple Snails Are Invasive Or Native? Both?

(c) DEP Florida / Island apple snail vs. native apple snail egg casings

Another day, another “I thought that was an invasive species” story to tell. This time, its the apple snails in the genus Pomacea that are on the line. At my current teaching spot we have an aquarium setup with Pomacea. They’ve taken to laying thousands of beautiful pink eggs in small casings on the glass sides of the display just above the water line.

A particularly bright college-aged student pointed them out, asked several questions about the eggs, and then told me something interesting: “You realize of course that apple snails are not a native species.” To which I replied, “Um, no I’m pretty sure that they are a native. We have the snail kite in Florida and its a specialist that consumes almost entirely apple snails. The kites are native. It seems odd that their food wouldn’t be… hmmmmm.”

I’m more than willing to be wrong of course, but the information certainly sent me for a loop. I was sent for a relative roller coaster ride this afternoon when I finally got around to looking up the apple snail history. Turns out there are several species of apple snail and while there is definitely a variety native to Florida – and natural prey for those kites – there are also invader species probably brought in through the aquarium industry in the state. And lo and behold those beautiful pink eggs are a dead giveaway that the snails we have are the invading Pomacea insularum, the island apple snail. (In the photo above invader eggs are on the left and native apple snail eggs are on the right.)

Its an explanation so simple I felt pretty sheepish writing it all down for future reference. At least I’ve learned something today: don’t be dismissive of things that you hear from your students, sometimes they know more than you do.

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2 Comments to “Apple Snails Are Invasive Or Native? Both?”

  1. One of the most awful smells in the world is the odor from a dead apple snail. Found this out the hard way while tubing down the Ichetucknee River. Found one floating at the surface and grabbed it. I soon realized the reason it was buoyant was because of decomposition gasses. Ugh, so rotten.

  2. Dead snails period are always disgusting! I used Ilyanass obsoleta (common mudflat snail up North) for bioassays in college. We lost a batch when a filter and a heater malfunctioned overnight. The oozing green sights in the aquarium should have warned me.. but when I opened the tank lid it was so overpowering we all had to excuse ourselves from the lab. Thank goodness for high volume air turnover in labs!!