Distribution & Habitat Preferences of the scorpion, Centruroides hentzi in central Florida State Parks
Abraham Miller PhD & Jennifer Fernandes University of Tampa St. Petersburg College, Tarpon Springs
Scorpion Background
Approx. 1500 species worldwide
All are nocturnal predators Glow green under UV light Give birth to live young
Long lived (5+ years) Paruroctonus boreus under blacklight All are venomous Photo by Ryan Stork
Scorpion Background
Major constituent of desert Biomass (Polis 1990) With exception of ants and termites, they have the greatest arthropod biomass Their biomass is higher than most vertebrates in the desert Paruroctonus boreus under blacklight
Photo by Ryan Stork Importance in Florida
Scorpions are major invertebrate predators
May represent healthy environment Don’t disperse well Require other invertebrates
May be a source for biological control
Centruroides hentzi from Highlands Hammock State Park Why C. hentzi in State parks?
Photo: Guy E. Crauwels (C) www.ntnu.no/ub/scorpion-files/gallery.php Lack of Information Public Information in the Western US Corey & Stout 1990 Corey & Stout 1990
Sampled 12 sites 6 arachnid orders; 14 species Scorpion: C. hentzi 4th most abundant of all taxa 86% collected between July-September Juveniles in September No correlation with ground cover
Shelley & Sissom 1995 Questions
What Florida State Parks have scorpions?
How common are scorpions in Florida?
What habitats do they occupy?
What do they prey on? Methods
Blacklight collecting at night between Feb - Nov Used GPS to mark location Scorpion locations were recorded Amount of Moonlight Vegetation Type Vertical height Distance to nearest Pine Tree Distance to nearest Oak Tree Distance to nearest saw palmetto
Laboratory Trial of Tree Preference Scorpions were placed in a large plastic container filled with sand Oak Log & Pine Log were placed vertically in the sand Scorpion location was recorded
What Florida State Parks have scorpions?
5 parks sampled in Central region What Florida State Parks have scorpions?
7 parks sampled in Southwest region Highlands Hammock S.P.
Highlands Hammock S.P.
Highlands Hammock S.P.
Highlands Hammock S.P.
Highlands Hammock S.P.
Habitat Preference
24% found on Saw Palmetto 120
1% found on Cabbage Palm 100
80
20% found on Pine Trees 60
1% found on Oak 40
20
54% found elsewhere (i.e. 0 ground, pine needles, logs, etc.) Pine Oak Cabbage Palm Saw Palm Other
Habitat Preference
24% found on Saw Palmetto 120
1% found on Cabbage Palm 100
80
20% found on Pine Trees 60
1% found on Oak 40
20
54% found elsewhere (i.e. 0 ground, pine needles, logs, etc.) Pine Oak Cabbage Palm Saw Palm Other
Experiment: Habitat Preference Experiment: Habitat Preference Experimental set-up needs to be revised Scorpions disappeared for days at a time, which heavily skewed data Scorpions were seen (active) every 3-14 days Scorpions came out to feed 3-5% of Scorpions are active on any night (Polis 1990) Experiment: Habitat Preference Results: Negative Phototaxis
85% of scorpions 160 143 collected were located in 140 the shadow of the moon 120
100
80
60
40
20 13 14
0 shadow partial shadow moonlight Other Results
Temporal Variation Prey Full Moon at St. Spiders Sebastian 3/7-3/8/12 Caterpillars 7 scorpions – clear Solpugids conditions Moths 3 scorpions after rain Crickets Waning Moon at St. Sebastian 5/21/11 Lacewings 15 captured Moon had not risen yet Unaffected by fire
Other Results
Vertical Stratification Do not burrow Have been seen at 5 meters up a pine tree Gravid Females Found in all areas Females carrying young All found associated with rotting logs on the ground Most (if not all) have termites Possible Food Source Discussion
Pine Trees & Saw Palmettos like offer the best refugia
Poorly drained areas decrease dispersal capabilities
There appears to be seasonality Abiotic Factors Biotic Factors
Abundance Observed 30+/hr along 100m trail
Why not C. hentzi Walk? CETL Funding
Used to set up a lab at the TS campus to get SPC AA and BS students involved in scientific research Need to purchase Black lights Housing containers Building materials for behavioral studies and other experimental supplies Crickets and a terrarium to breed them Light timers Sand Dissecting microscope Acknowledgements
St Petersburg College Florida Biology Class for field help CETL
Florida Department of Environmental Protection Collecting Permit Thanks & Questions