The Largest Arthropod Ever!

Caption below under next figure: Image from “Giant claw reveals the largest ever arthropod” (2007), Biology Letters

The arthropods we are familiar with today tend toward the small side compared to the some of the giants found in the fossil record. From the Late Palaeozoic, 2m long millipedes and dragonflies with 75cm wingspans are known. Even marine arthropods obtained large sizes with examples including Ordovician trilobites and Siluro-Devonian eurypterids (sea scorpions). In part the Late Paleozioc pattern might be explained by increased atmospheric oxygen levels. Work on extant groups like arthropods and mollusks seem to support a pattern between oxygen and body size.


A new individual of eurypterid described by Braddy et al. appearing in Biology Letters may shatter the old record of 250cm length of Acutiramus bohemicus. The new individual is a Jackelopterus rehnaniae from the Early Devonian Willwerath Lagerstatte of Germany. The description and estimated length are based on a single discovered claw (chelicera). Using chelicera/total length ratios from two closely related genera, Acutiramus and Pterygotus, the authors estimate the length (without chelicerae) to be between 233-259cm and 333-359 with the additional length of the chelicerae. The tremndous size of such an animal suggests a top predatory position pontentially feeding on other arthropods and early vertebrates (Inverts 1 Verts 0)
From the Telegraph: Markus Poschmann with the giant sea scorpion fossil

P.S. the species was not from the deep sea but rather a reef predator

Dr. M (1801 Posts)

Craig McClain is the Executive Director of the Lousiana University Marine Consortium. He has conducted deep-sea research for 20 years and published over 50 papers in the area. He has participated in and led dozens of oceanographic expeditions taken him to the Antarctic and the most remote regions of the Pacific and Atlantic. Craig’s research focuses on how energy drives the biology of marine invertebrates from individuals to ecosystems, specifically, seeking to uncover how organisms are adapted to different levels of carbon availability, i.e. food, and how this determines the kinds and number of species in different parts of the oceans. Additionally, Craig is obsessed with the size of things. Sometimes this translated into actually scientific research. Craig’s research has been featured on National Public Radio, Discovery Channel, Fox News, National Geographic and ABC News. In addition to his scientific research, Craig also advocates the need for scientists to connect with the public and is the founder and chief editor of the acclaimed Deep-Sea News (, a popular ocean-themed blog that has won numerous awards. His writing has been featured in Cosmos, Science Illustrated, American Scientist, Wired, Mental Floss, and the Open Lab: The Best Science Writing on the Web.

3 Replies to “The Largest Arthropod Ever!”

  1. Wow! Thank God for Evolution! I’m really, really glad this monster wasn’t trawling the reefs when I was diving!

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