Study: Sea spiders use guts to pump oxygen

WASHINGTON - Most animals depend on a beating heart to pump blood and oxygen, but sea spiders do this mostly with their unusual guts, according to a new study published on Monday.

"Unlike us, with our centrally located guts that are all confined to a single body cavity, the guts of sea spiders branch multiple times and sections of gut tube go down to the end of every leg," lead author H. Arthur Woods of the University of Montana, Missoula, said in a statement.

"In effect, sea spiders guts are 'space-filling' and ubiquitous in their bodies in the same way that our circulatory systems are space-filling and ubiquitous."