Giant Great South Bay Horseshoe Crab

Giant Great South Bay Horseshoe Crab
An AI rendering of the giant Great South Bay horseshoe crab (Limulus giganticus) that was published alongside the original local newspaper article that brought attention to this cryptid.
Background
First Sighting	March 2025
Country	United States
Possible Population	Unknown

The giant Great South Bay horseshoe crab (Limulus giganticus) is a cryptid first reported in Long Island, New York, specifically in the waters of the Great South Bay and Fire Island National Seashore in March 2025. The creature resembles an 8-foot-long horseshoe crab. It was first reported on by Fire Island and Great South Bay News in April of 2025, with the local newspaper reporting that eight eyewitnesses had seen the organism.

"I have led a lot of horseshoe crab events; I know horseshoe crabs. That thing was definitely a horseshoe crab but it was not the species we know. These things are not just passing through; in my opinion, they have come here to breed."

—Anonymous Fire Island National Seashore Park Ranger

Sightings

All of the known sightings of the giant Great South Bay horseshoe crab were reported by Fire Island and Great South Bay News in April of 2025. The article mentions eight sightings but only three of them were reported in detail. In one, a woman named Jem Patterson saw the creature in the water while out on a hike on March 6th. In the second a fisherman identified only as "Bobby" accidentally hooked the giant crab while fishing off the coast of the Fire Island Wilderness and lost his favorite fishing rod in the process. Finally, in a third sighting, an anonymous park ranger claims to have witnessed two of the crabs engaging in courtship behavior.

Description

One eyewitness described the crab as a horseshoe crab but “longer than a surfboard and three times as wide” and "neon yellow." Other witnesses say the crabs are the more typical brown of normal Atlantic horseshoe crabs. While other witnesses say they saw crabs of both colors mating. This last sighting implies that the species is likely sexually dimorphic, with one sex being neon yellow and the other being brown. It is not known which gender is associated with which color at this time.

Hypothesized Medical Uses

Ordinary horseshoe crab blood has been used to develop many medical advancements, specifically vaccines. It has been hypothesized that the blood of the giant Great South Bay horseshoe crab may also have medical applications. One scientist interviewed by Fire Island and Great South Bay News hypothesized that the blood "may hold the cure to baldness and many other diseases."

Explanations

There are many possible explanations for the giant Great South Bay horseshoe crab. It could be a new species, a mutation, or a mass hallucination. However, the most likely explanation for the creature is that it is an April Fools joke published by the reporter in the paper to satirize a decision by New York State Governor Kathy Hochul to veto a bill protecting horseshoe crabs and recent actions taken by US President Donald Trump against the National Park Service. This is most likely because the original article asserting the possible existence of the creature was released on April Fools' Day. However, the article may also have been released under the guise of a practical joke to get the article published.