Invasive species are organisms introduced outside their native range that cause harm to the environment, economy, or human health. Florida is uniquely vulnerable to these biological invasions, hosting more non-native reptile and amphibian species than any other state. The state’s subtropical to tropical climate allows foreign species to thrive year-round without a harsh winter die-off. Florida’s extensive coastline, numerous international ports, and massive trade volume, particularly in the exotic pet and horticulture industries, provide constant pathways for new introductions. Once established, these organisms often lack natural predators, allowing populations to grow unchecked and disrupt native ecosystems.
Prominent Terrestrial Animal Invaders
The Burmese python (Python bivittatus) is one of the most destructive terrestrial invaders, having established a massive breeding population in the Everglades. These constrictors, which can exceed 18 feet in length, primarily entered the ecosystem through the exotic pet trade via intentional releases and accidental escapes. Their presence has coincided with a collapse of native mammal populations in the Everglades National Park, with observations of raccoons, opossums, and bobcats declining by over 90% in some areas. Pythons are apex predators that consume a wide variety of prey, including endangered native birds and alligators, fundamentally altering the food web structure. They also carry an Asian lungworm parasite that can infect and harm native Florida snake species.
The Argentine black and white tegu (Salvator merianae) is another significant reptilian threat, reaching nearly five feet long. Tegus arrived primarily through the pet trade and have established populations in several counties. They pose a direct threat to ground-nesting wildlife, as they are voracious egg predators, consuming the eggs of native birds, American alligators, and the threatened gopher tortoise. Their ability to enter a hibernation-like state called brumation allows them to survive cooler Florida winters, suggesting a high potential for continued northern expansion.
Green iguanas (Iguana iguana) are common in urban and suburban areas of South Florida, introduced through the pet trade and as stowaways on cargo ships. While primarily herbivorous, these lizards consume native vegetation and prey on native bird eggs and tree snails. Their habit of digging extensive burrows contributes to infrastructure damage, undermining sidewalks, seawalls, and foundations. The iguanas also create sanitation concerns, as their droppings can transmit Salmonella to humans.
Aquatic and Marine Intruders
In marine environments, the Indo-Pacific lionfish (Pterois volitans and P. miles) is the first non-native marine fish to successfully establish itself in the Atlantic and Gulf of Mexico. Lionfish are voracious predators that consume over 70 species of native fish and invertebrates, including snapper and grouper juveniles. Their presence on coral reefs reduces native algae-grazing fish populations, leading to rapid algae overgrowth that smothers and degrades coral health. The species reproduces year-round and has no natural predators in Florida waters, allowing for rapid population growth.
The Giant African land snail (Lissachatina fulica) is a terrestrial mollusk that represents a health and agricultural menace. These snails, which can grow up to eight inches long, consume more than 500 types of plants, posing a direct threat to Florida’s agricultural industry. The snail also serves as a vector for the rat lungworm parasite, which can cause eosinophilic meningitis in humans. State agencies have implemented strict quarantine and eradication efforts to prevent the spread of this damaging pest.
Florida’s freshwater systems are heavily impacted by non-native aquatic plants like hydrilla (Hydrilla verticillata) and water hyacinth (Eichhornia crassipes). Hydrilla, a rooted, submerged plant introduced via the aquarium trade, forms dense underwater mats that displace native vegetation. When these mats die and decompose, they consume large amounts of dissolved oxygen, which can trigger massive fish kills. Water hyacinth forms thick carpets on the surface of rivers and lakes, blocking sunlight, impeding navigation, and restricting oxygen exchange.
Ecological and Economic Consequences
The collective presence of invasive species inflicts profound ecological damage by threatening the survival of native Florida species. Predation by animals like the Burmese python and competition from the lionfish can cause local extinction of native populations, destabilizing entire food webs. Invasive plants fundamentally alter habitats; for example, hydrilla and water hyacinth change water chemistry and block sunlight, affecting aquatic life. This widespread ecosystem disruption reduces the overall biodiversity that makes Florida’s natural areas unique.
The economic costs associated with these invaders are substantial, affecting multiple sectors. Agricultural losses from non-native pests and plants are estimated to reach nearly $180 million annually. Infrastructure suffers damage from species like the green iguana, whose burrowing erodes seawalls and foundations, and from aquatic plants that clog canals, requiring costly dredging and maintenance. The cost of managing invasive plants alone in natural areas is approximately $45 million each year, a figure that does not include the substantial expenditures for animal control programs, which collectively represent hundreds of millions of dollars in continuous expenses.
State Efforts in Containment and Control
The Florida Fish and Wildlife Conservation Commission (FWC) and the Florida Department of Agriculture and Consumer Services (FDACS) manage a multi-pronged strategy to contain and control invasive species. The regulatory framework classifies non-native animals into Prohibited and Conditional species lists, restricting or banning the possession of the most dangerous invaders, including the Burmese python, tegu, and green iguana. This measure aims to prevent new introductions from the exotic pet trade, and enforcement relies on public cooperation and reporting.
The state actively engages citizens through programs like the annual Python Challenge, a competition designed to incentivize the removal of pythons from the Everglades. To facilitate early detection and rapid response, the FWC maintains the IveGot1 app and an Invasive Species Hotline (888-Ive-Got1) where the public can report sightings. These reports are crucial for tracking the spread of established invaders. In freshwater systems, state agencies use mechanical harvesting, chemical treatments, and biological controls to maintain aquatic plant populations at manageable levels.