UF/IFAS Okeechobee County Extension Service

458 Highway 98 North

Okeechobee, FL 34972-2578

Phone: (863) 763-6469

E- mail:  dfculbert@ifas.ufl.edu

Quick Links:    Florida Applesnail   spiketopped applesnail  Channeled applesnail  ID of shells    ID of eggs   Management ideas   Report your finds to:    References    

September 1, 2005

Feature Article - for release the week of September 4, 2005

Dan Culbert - Extension Horticulture Agent

A New slimy invader 

Meet "Tiny", a Channeled Applesnail. (Note the quarter for an idea of her size) The smaller shell is  a native, Florida Applesnail. Photo by Dan Culbert.

One of the visitors to our recent Pond Appeal program came as a special invited guest.  She didn’t walk in, but came along in the bottom of a bucket.  At one point, this fist-sized snail slimed her way off the observation plate and was headed for the floor.  Now this wasn’t a plate of escargot, but a new slimy invader in Florida.  Hopefully, this will be the first and last time our county has a visit from the Channeled Apple Snail, a new invasive pest in Florida.

One kind of applesnail is a native of Florida freshwater areas. It is the primary food source of an endangered bird, the Everglades Kite.  Unfortunately, other kinds two apple snails found in Florida are invaders.  Our visitor, named “Tiny” by local Extension Agents Janet Bargar and Ken Gioeli, was found recently in a Vero Beach canal.  If she wasn’t executed after our class, she and her offspring would have gotten bigger and eaten up all kinds of plants in and around ponds and lakes.

The native Florida applesnail (Pomacea paludosa) can be found anywhere in the Florida peninsula. It should be considered a good guy, as it is the principal food of the Everglades Kite (Rostrhamus sociabilis plumbeus).  The native applesnail has been here since the end of the Ice Age.  It cannot survive low winter temperatures, so it is not found in northern Florida unless the water is artificially heated.  At full size, it’s slightly bigger than a quarter. The shape of the spiraling shell includes a low rounded shell spike.

A slightly bigger spiketopped applesnail (P.  bridgesi) was introduced into South Florida from Brazil in the l950s. They feed mostly on decaying vegetation. It doesn’t like the cold, so escaped “spikers” are only known in Broward, Miami-Dade, Monroe and Palm Beach counties.  Unfortunately, commercially bred aquarium varieties, like the "albino mystery snail", are sometimes dumped into ponds and have been recovered as far north as Gainesville. 

However, it is the third species, the Channeled applesnail (P. canaliculata) that is a concern.  It grows to be nearly twice the size (up to 4 inches) as the other two species and has become a serious rice pest in many countries.   Introduced into South Florida from Paraguay in 1978, it was also released into Hawaii and Asian countries.  It also can host a human parasite, the rat lung worm, making it a problem for human consumption as Escargot.

 A comparison of Florida Applesnail shells    All photos by Jeffrey Lotz, FDACS DPI

Click on this link and scroll down page to go to  3-D pictures! 

Florida applesnail (Pomacea paludosa)

Spiketopped applesnail Pomacea bridgesi

Channeled applesnail Pomacea canaliculata

The Channeled applesnail can survive out of water for up to 5 months, and can hibernate in the mud during cold weather.  It can live for more than two years, making it desirable as an aquarium pet.   In Florida, the species has been found in warmer coastal areas like Collier, Hillsborough, Palm Beach counties.  Recent reports have it in Seminole County and even in Jacksonville.   It is now found in Texas and California and has caused alarm there because of their rice production.  

The problem with this critter is that it feeds aggressively on many types of aquatic and terrestrial plants, such as taro and rice.  But, before the idea of it being used to control aquatic weeds is brought up, it does not eat Brazilian Pepper, cattails or hydrilla.  

Besides size, this snail can be distinguished by the deep groove or channel between the whorls of the shell.  Another item to look for is the grape-like clusters of pink to red eggs.  The females crawl out of the water and deposit what looks like pink caviar on walls or grasses above the water.  Sighting clusters of up to 1000 pink eggs is the fastest way to determine if applesnails are present. 

These eggs were one of two clutches that "Tiny" laid in one week.  (Note penny at top of photo for size.) Photo by Dan Culbert.

  A comparison of eggs of the invasive Channeled Apple Snail (left) and the native Florida Applesnail (right).  Photo above courtesy Dana Denson, FLDEP

Compared to the eggs of native apple snails, those of “Tiny’s” relatives are smaller, pinker, and more numerous. Eggs darken and hatch in one to two weeks, releasing hundreds of juveniles into the lake. Physical removal of eggs and adult snails would help in reducing the numbers of these invasive animals. 

Although there might be some local wildlife that will eat these snails, our predators have not shown much interest in or ability to eat them.  They threaten native plants and wildlife by feeding on the aquatic plants needed by invertebrates that are fed on by small fish, which are themselves eaten by larger fish like largemouth bass and crappie. 

To help slow the spread of more snails like Tiny, if you have them in aquariums, don’t dump them into ponds outdoors or other natural water body. To dispose of unwanted snails, put them in a sealed plastic bag and freeze. Once frozen, put them - still in the bag - into the garbage. 

If you find these channeled apple snails and/or their eggs, please contact Dana Denson, Aquatic Biologist, Florida Department of Environmental Protection,  dana.denson@dep.state.fl.us, or call (407) 894-7555, ext. 2355.

If you discover what you suspect is this invading snail or its eggs, please report them to the authorities.  Be sure it is not a native apple snail or its eggs, which are larger lighter in color and are fewer in number than the eggs of the invader.  Any pink egg masses or adults found in the wild can be easily removed from hard surfaces near the water.  They can also be bagged and frozen.   

I’ve placed photos and more information on our Okeechobee web page, http://okeechobee.ifas.ufl.edu.  If you need additional information on the Channeled or giant applesnails, please email us at okeechobee@ifas.ufl.edu or call us at 863-763-6469.  Local residents can stop by our office at 458 Hwy 98 North in Okeechobee, and visit our Okeechobee County Master Gardeners on Tuesday afternoons from 1 to 5 PM.  

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Trade names, where used, are given for the purpose of providing specific information. They do not constitute an endorsement or guarantee of products named, nor does it imply criticism of products not named. The Florida Cooperative Extension Service - Institute of Food and Agricultural Sciences is an equal opportunity/affirmative action employer authorized to provide research, educational information, and other services to individuals and institutions that function without regard to race, color, sex, age, handicap, or national origin.  Florida Cooperative Extension Service / IFAS / University of Florida.  Larry A.  Arrington, Dean Last update: 09/01/2005 .  This page is maintained by Dan Culbert  Hit Counter

references

Denson, Dana & Eby,Gloria.  LAKE BRANTLEY INFESTED WITH INVASIVE SNAILS. Orlando: FLDEP, July 2005. [Newsletter article]

Denson, Dana.  Invasive Exotic Snails in Central Florida Waterways (website), Orlando: FLDEP,2005. 

Ghesquiere, Stijn   Applesnail.net website, 2005   [The definitive website for all kinds of information on Applesnails]  

Harris, Rachel. "Giant snail could imperil natives, water."  West Palm Beach: Palm Beach Post, 9/10/05 [Link at: http://kgioeli.ifas.ufl.edu]logo2

Stange, L.A.    Featured Creatures: Apple snails of Florida. (EENY-323)  Gainesville: Florida Cooperative Extension Service Featured Creatures bulletin, March 2004.  http://edis.ifas.ufl.edu/IN598 .  (Originally published as DPI Entomology Circular 388, Florida Department of Agriculture and Consumer Services, Division of Plant Industry) http://creatures.ifas.ufl.edu/misc/gastro/apple_snails.htm