First venomous crustacean

The first known species of venomous crustacean is Xibalbanus tulumensis (formerly Speleonectes tulumensis). A blind remipede crustacean first identified in 1987, it inhabits anchialine caves (underwater caverns connected to the ocean) of the Yucatán Peninsula in Mexico, and feeds upon other crustaceans. Its hunting strategy involves using its front claws to inject prey with a toxin similar to rattlesnake venom that breaks down the victim's internal body tissues, turning it into liquid that the remipede then sucks up and ingests.

Remipedes, of which there are currently 28 known species, were only described for the first time in 1981. Since the discovery of Xibalbanus tulumensis in 1987, three further species in the genus have been reported: X. fuchscockburni (2012; Yucatán Peninsula), X. cokei (2013; ocean cave near Caye Chapel, Belize) and X. cozumelensis (2017; Cozumel island).

Suspicions that Xibalbanus tulumensis might be venomous first arose in 2007 when researchers noticed its claws were like "hypodermic needles", however it was only with further research that they uncovered associated musculature designed to pump fluid and connected glands in the body where venom is produced.

The findings were published in the journal Molecular Biology and Evolution on 16 October 2013. The study was a collaboration between the Natural History Museum (UK), the University of Leipzig, Zoologisches Forschungsmuseum Alexander Koenig (both Germany) and Universidad Nacional Autónoma de México (Mexico).