A Closer Look At The Euglandina rosea (Férussac, 1821) In Northern St. Johns County, Florida

The image below shows the study area along US-1in northern St. Johns County. The view is looking towards the northwest.

    During a field survey during the fall of 2015, this reporter discovered an usually large population of Euglandina rosea in the roadside swale and adjacent swampy area along US-1 in northern St. Johns County, Florida. This population, present on both the east and west sides of the road, was found to extend for a distance of about three miles with the southern end of the habitat being about 3.1 miles northwest of International Golf Parkway. The highest concentration of specimens was found in the southern end of the habitat. Not only were the snails present in large number as compared to other Florida locations, but their overall size was much larger than might be found elsewhere. An empty shell measuring 87 mm. was found on 10/12/2015 and a living 82.8 mm. specimen was later found on 3/2/2019. To the best of our knowledge it appears likely that the 87 mm. specimen may be the largest Euglandina rosea ever found with the 82.8 mm. shell being the largest living Euglandina rosea ever collected.

    Between 2015-2018 the site was visited on a periodic basis. While it was initially thought that the largest concentration of specimens was on the east side of the US-1, more frequent visits to the site during 2018 indicated that it was the west side of the road that in fact probably had a much larger population. The question then became as to just how large the population really was. To attempt to answer this question, an approximate half a mile stretch of the swale was selected for closer study. Between 1/14/2019 and 4/4/2019 a total of 36 visits were made to the site. All living Euglandina found (excluding juveniles under 25 mm.) were marked (tagged) with brightly colored nail polish. By the end of the study period 97 individuals had been tagged. During that period there were a total of 58 recoveries of tagged specimens. Some of the tagged specimens were recovered on multiple occasions thus the recovery rate was rather low as compared to the number of tagged specimens present.

    While it will never be known for sure exactly how many Euglandina inhabit the roadside swale in the study area, the presence of nearly 100 adult snails in a half mile stretch of swale along a very busy four lane highway was surprising.


Nr. Specimens Tagged

Tagged Specimens Recovered And Then Released Recovered Specimens Color


1/14/2019 2     started tagging with neon orange
1/16/2019 3      
1/19/2019 11      
1/20/2019 6      
1/22/2019 1      
1/23/1019 3 2 orange  
1/25/2019 3 1 orange same shell same as 1/23/2019
1/28/2019 4     started tagging with neon green
1/29/2019 0      
1/31/2019 2      
2/2/2019 4 2 1-orange, 1-green  
2/3/2019 4 3 1-orange, 2-green  
2/6/2019 6 1 orange  
2/8/2019 5 1 orange  
2/10/2019 4 2 1-orange, 1-green orange specimen was in a mating pair
2/12/2019 3 1 green  
2/14/2019 0 1 green empty shell, victim of cannibalism
2/16/2019 3 5 2-orange, 3-green one of each color was in a mating pair
2/19/2019 3 1 orange  
2/22/2019 3 3 1-orange, 2-green one green specimen was in a mating pair
2/24/2019 4 3 green  
2/26/2019 0 2 green  
2/28/2019 4 3 green one green specimen was in a mating pair
  -77- -31-    
3/2/2019 4 1 green started tagging with "Bora Bora"
3/5/2019 1 1 green  
3/7/2019 1 1 "Bora Bora"  
3/9/2019 2 3 1-green, 1-orange, 1-"Bora Bora"  
3/11/2019 0 3 1-green, 1-orange, 1-"Bora Bora"  
3/13/2019 0 3 2-green, 1-orange  
3/15/2019 3 1 orange  
3/17/2019 3 1 "Bora Bora"  
3/19/2019 1 3 2-green, 1-"Bora Bora"  
3/21/2019 1 2 1-green, 1-"Bora Bora"  
3/23/2019 1 2 1-green, 1-"Bora Bora"  
3/26/2019 3 2 1-orange, 1-"Bora Bora" green tagged snails starting to show wear
3/28/2019 0 3 2-green, 1-orange  
3/20/10/19 0 0   one live specimen found/kept/not tagged
4/4/2019 0 1 1-green  
  -97- -58-    


--Between the initial tagging which began on 1/14/2019 and 5/13/2019, three of the 97 tagged specimens were found deceased (one each green, orange, and "Bora Bora"tagged). The green tagged specimen appeared to have been the victim of cannibalism (2/14/2019 above) while the remaining two appeared to have perished due to natural causes based upon their in situ positioning when recovered on 5/10/2019.
--Between 10/2015 and 5/2019, a total of 24 Euglandina measuring 76 mm. or larger were found in the US-1 Euglandina snail habitat. A vast majority of which were empty shells with most of them found on the east side of US-1. Henry Pilsbry (1946) reported a 76 mm. Euglandina rosea from Palatka, Putnam County Florida which appears to be the largest specimen ever formally documented.
--Between 10/2015 and 5/2019, a total of 406 specimen quality adult Euglandina rosea shells were collected from the Euglandina habitat along US-1 and retained. A majoriy were empty shells. An extimated 200 additional shells (including the extant 94 living tagged specimens) were found but not retained.