Scattered throughout Mesoamerica are pools where water surfaces from underground networks of caves, which the ancient Maya said were gateways to the underworld. Biologists have now found that these bodies of water are home to a mysterious real-world creature as well: the first venomous crustaceans known to science.
The crustacean in question, Speleonectes tulumensis, belongs to the remipedes, a group first described in 1981. Observing these pale, blind and tiny animals in their natural habitat has been hard because they live in labyrinthine cave networks that are as difficult for divers to navigate as they are dangerous.
In 2007 researchers discovered structures on the animals’ front claws that resemble hypodermic needles, fuelling speculations that they might be injecting something into their prey. The researchers found that reservoirs attached to the needle structures are surrounded by muscles that can pump fluid through the needles. Moreover, they found glands in the centre of the remipede body that manufacture venom and are connected to the reservoirs.
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Also found that the crustaceans’ venom is made predominantly of peptidases, enzymes that have roles in digestion and are also found in rattlesnake venom, where they help to digest prey. The crustacean venom also contains a toxin that is nearly identical to a paralysis-inducing neurotoxin first described in spiders in 2010.
Although venom is common in arthropods such as spiders, scorpions, centipedes and wasps, it has never before been seen in any of the 70,000 known crustaceans, a subgroup of arthropods that includes shrimp and crabs. Why it is so rare in this subgroup remains an open question.
The reason is that the diet of crustaceans is much more varied than that of venomous predators.
Source | nature.com