Sea Spiders Pump Oxygen With Their Guts, Not Hearts
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.
“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.
The study, published in the U.S. journal Current Biology, found that sea spiders, which take in oxygen directly through their cuticles, use gut peristalsis to move fluids.
In fact, the human gut also uses peristalsis – waves of involuntary constriction and relaxation of muscles — to mix gut contents and move them along.
Scientists had long observed that polar species, including giant sea spiders, have larger bodies than their more temperate or tropical relatives.
One of the things that make sea spiders a great organism for study is “that they are really skinny and, using a microscope, you can see easily into their bodies,” Woods said.
In contrast, he noticed, their guts showed very strong and organized waves of peristaltic contractions, which are much more vigorous than would be needed for digestion.
It’s not clear whether the sea spiders’ space-filling guts first arose for purely digestive functions and the respiratory benefits came later or vice versa, the study said.
“Respiratory gut peristalsis may be more widespread than previously recognized,” the researchers wrote in their paper.
“Although (sea spiders) are unusual in having gut diverticula in almost all body spaces, partially space-filling guts are common in other arthropods, suggesting that guts could transport gases in these other groups.”
Please like, share and tweet this article.
Pass it on: Popular Science