Campaigners hope their objections to a new theme park which has been dubbed the "UK's answer to Disneyland" will see the project axed.
Wildlife group Buglife has launched the campaign to Save Swanscombe Marshes after The London Resort appealed for public input into the plans.
The £3.5billion theme park plans were first announced in 2012 and it is set to open in 2024 with six differently-themed areas across its 535-acre site – although there are already plans prepared for it to be extended even more by 2029.
But campaigners say the marshes where the theme park would be are home to thousands of invertebrate species, including over 250 that are "of conservation concern".
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Among these is the Critically Endangered Distinguished jumping spider, which only exists in one other part of the UK.
A petition started by the group has already gained nearly 1,000 signatures, Kent Online reports.
Buglife planning lead, Jamie Robins said: "Brownfield sites like Swanscombe Marshes are some of the most important places in the country for our threatened invertebrates.
"Our No Insectinction manifesto calls for ‘safe spaces’ for invertebrates - it is essential that we save this nationally-important wildlife haven from destruction.
"The London Resort Theme Park would be no fun for nature. Buglife wants to protect this wildlife haven from unnecessary and ill-thought development, saving it for future generations to enjoy.
"Last year, planning was granted which will destroy the nearby Tilbury Marshes another top quality open mosaic habitat, to allow for port expansion. Enough is enough, it is time to start valuing nature."
Andy Martin, from London Resort Company Holdings (LCH) told Daily Star Online: "We welcome everyone’s input at this stage of public consultation. We are committed to delivering a net gain in biodiversity.
"The peninsula suffers from extensive areas of historical waste disposal, contamination and old industrial structures.
"LRCH has been conducting comprehensive, environmental analysis on the site since 2012 and we are acutely aware of its evolving wildlife.
"Ecological analysis is continuing to inform a comprehensive habitat enhancement and biodiversity strategy to support the Resort development," continued Martin.
"While we continue working to identify and protect species of special interest, our proposals will address legacy environmental problems without creating new ones.
"The London Resort will enable the enhanced management of contaminated land, include a sustainable drainage strategy, which will improve water quality and actually deliver enhanced habitats for wildlife."
Artists impressions of what the final park will look like were released last December, and now a full plan for the park has gone to public consultation, with members of the public now urged to comment on what they think of them.
It would be the first park of its kind to be built in Europe from scratch since Disneyland Paris in 1992.
Bosses behind the plan have claimed 9,000 direct and 20,000 indirect jobs would be created for the resort within its first year.
They insist it would rise to 17,000 and over 35,000 respectively after 15 years, and includes roles for a range of people from high-tech engineers to seasonal part-time workers.
If successful in securing development consent, construction could begin in early 2022 for the park's grand opening in 2024.
The resort will include two theme parks, a water park, conference venues, hotels, retail and dining.
A large proportion of the peninsula will be "enhanced for wildlife," with quiet zones for visitors and the public to relax.
The consultation period runs until September 21.