|The horseshoe crab (left) and its namesake (right). Credit: NM Museum of Natural History & Science / Youtube.
A 245-million-year-old fossil shows a strange invertebrate with a head the shape of the letter D and a long tail. The scientists who discovered the fossil thought that the prehistoric creature looked kind of like a Star Wars villain, so they named it after the movie’s most infamous one: Vaderlimulus tricki.
Horseshoe crabs appeared on Earth 470 million years ago, but this one lived more recently, during the late Triassic era, when the first dinosaurs were just evolving. Horseshoe crabs are actually still alive today, and that means they have survived five mass extinctions. You might even see them scuttling around beaches on the East Coast of the United States or in Eastern Asia.
Horseshoe crabs, whether ancient or modern, are in the subphylum Chelicerata, which means that their closest living relatives are spiders and scorpions. In common with spiders and crabs, they have exoskeletons, but horseshoe crabs are not technically crabs. Their crab-like legs are hidden under a wide shell with eyes on the top.
This body shape is not always an advantage. If they end up on their back, they can use their long tails to right themselves, but sometimes that can be hard. The South Carolina Sea Grant Consortium has put together a brochure on how to flip a horseshoe crab to help it get back to doing horseshoe-crab things.
Despite having survived for hundreds of millions of years, through strange forms of evolution, the rise and fall of the dinosaurs, and several mass extinctions, the numbers of modern horseshoe crabs are depleting. They are easy to catch and are sometimes used in fertilizer. Meanwhile, some scientists harvest their blood to make medicine. While the animals are usually returned to the ocean after, those individuals have a high mortality rate and low spawn rate.
The discovery of this Darth Vader–like crab, with its oversize helmet and small body, shows the diversity of horseshoe crabs. If they can survive humanity, maybe they will live another hundred thousand years after us.
The study was published in the journal Neues Jahrbuch für Geologie und Paläontologie.