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Feb 27, 2019 · Bizarre horseshoe crabs are actually spider relatives. The primordial ocean dwellers are squarely situated in the arachnid family tree, scientists claim in a new study. By Nadia Drake.
- 3 min
Mar 9, 2019 · Horseshoe crabs have been challenging to classify within the arthropods because analysis of the animals' genome has repeatedly shown them to be related to arachnids like spiders, scorpions,...
- They’re living fossils. These ocean critters predate the dinosaurs! The oldest known horseshoe crab species, (Lunataspis aurora) was discovered by scientists in 2008 and is estimated to be nearly 450 million years old.
- No, they’re not actually crabs. Horseshoe crabs are much more closely related to arachnids like spiders and ticks than true crabs. They’re part of the Subphylum Chelicerata and are further classified into Class Merostomata, which includes horseshoe crab species as well as eurypterids (sea scorpions).
- They’ve got legs near their mouth. While their primary sets of legs are used to help them move around, the pair of legs that’s closest to their mouth is actually a set of pincers, which they use to move food closer to their mouth and crush it up to be easier to consume.
- They’re not dangerous. While many people mistakenly associate these animals with rays or skates because of their shape, they’re actually not related and aren’t dangerous at all.
Horseshoe crabs are the sister group to ricinuleids, and are within the family Arachnida, classifying them as aquatic arachnids. Their aquatic nature is the result of a secondary shift to marine life, following the initial shift to land by the common ancestor of all arachnids.
Overview. Horseshoe crabs are evolutionary survivors that have remained relatively unchanged in appearance for 350 million years. The horseshoe crab is not actually a true crab, but a member of an ancient group of arthropods, closely related to spiders and scorpions.
Feb 18, 2022 · Act of ‘Heresy’ Adds Horseshoe Crabs to Arachnid Family Tree. A team of researchers say that rather than occupying their own branch in the history of life on Earth, horseshoe crabs are in...
Feb 8, 2022 · Analyses of the two data sets failed to recover arachnid monophyly, instead placing horseshoe crabs within Arachnida. The findings have far-reaching implications, as it may indicate that horseshoe crabs have colonized the marine environment secondarily, from a terrestrial arachnid ancestor.
