Spider's Brain is So Large It Overflows to Its Legs

Image: Wcislo Lab

The brains of tiny spiders are SO large that they fill their body cavities and overflow into their legs:

“The smaller the animal, the more it has to invest in its brain, which means even very tiny spiders are able to weave a web and perform other fairly complex behaviors,” said William Wcislo, staff scientist at the Smithsonian Tropical Research Institute in Panama. “We discovered that the central nervous systems of the smallest spiders fill up almost 80 percent of their total body cavity, including about 25 percent of their legs.”

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