The Atlantic horseshoe crab is a species of xiphosuran chelicerate in the Limulidae family. It can reach 60 cm in length and 30 cm in width.
Despite its name, this species is more closely related to spiders and scorpions than to crabs, with which it bears no relation.
It is an ancient animal that could disappear from the coasts of Yucatán.
And now, a devastating scene has alerted the scientific and environmental community of Yucatán: 112 dead horseshoe crabs, mostly adult males, were found in just 1.5 kilometers of coastline in the Ría Lagartos Biosphere Reserve, one of the country’s most important areas for coastal biodiversity.
The discovery, unprecedented in more than a decade of monitoring, was made by biology students from the Tizimín Institute of Technology as part of the TecNM 2025 Scientific Summer Program.
Accompanied by researcher Juan José Sandoval Gío, the students collected water samples and exoskeletons in the town of El Cuyo, in eastern Yucatán, where they documented the unusual mortality.
The research professor said that evidence of dead horseshoe crabs, whose scientific name is Limulus polyphemus, should be taken with caution because this species is categorized as endangered by Semarnat (National Semarnat).
Sandoval Gío, head of the Aquaculture and Marine Biotechnology Laboratory at the TecNM Tizimín campus, warned that this is the first time that a mortality of such magnitude has been reported in Limulus polyphemus.
Although the causes are still being investigated, one of the main hypotheses is the extreme rise in water temperature, which may have exceeded the tolerance levels of this ancient species.
However, the history of chronic pollution in the estuary is also significant: glyphosate, heavy metals, and hydrocarbons have been detected in previous studies conducted in the same area.
“All the specimens analyzed contained glyphosate. We found residues in the sediment, in the freshwater, and in the saltwater.
The horseshoe crabs likely ingested contaminated organisms,” explained the researcher, who has led a marine toxicology investigation in the reserve for seven years.
In addition to glyphosate, the illegal capture of these endangered animals for use as bait in octopus fishing has been reported, further aggravating their situation.
Their disappearance could have a knock-on effect on key ecosystem species, such as sea turtles and the pink flamingo, which also depend on the ecological balance of Ría Lagartos.
“What’s happening here is not an isolated case; it’s a warning sign. If we don’t act, we won’t just lose one species, but an entire ecosystem,” warned Sandoval Gío.
The collected samples are already being analyzed in the laboratory, while red flags are being raised in eastern Yucatán regarding this environmental tragedy, which may be only the beginning of a larger disaster, given that the area is home to the pink flamingo and sea turtle species.
Sources: Yucatan a la mano / POR ESTO
