We’re used to thinking that animals utilize their pounding hearts to circulate blo.od throughout their bodies, but scientists have discovered one bizarre exception.
The terrifying sea spider, which is not an arachnid despite its name, utilizes its intestines to pump blo.od and oxygen throughout its spindly body.
The spider’s intestines extend via its gangly legs, which also house its ge.nit.al.ia. Because there is limited room for organs in the sea spider’s small abdomen, almost all of its physiological activities are restricted to its short legs.
While scientists previously knew that the animal utilized its legs for breathing, digesting, and even ma.ting, they have recently discovered that they are also employed to pump blo.od and oxygen.
‘Unlike ourselves, who have centrally situated guts that are entirely restricted to a single body cavity, sea spider guts branch numerous times, and pieces of gut tube run down to the end of every leg,’ said lead author Dr Art Woods of the University of Montana, Missoula.
Dr. Woods grew interested in huge sea spiders while stationed in Antarctica, where he spent “a lot of time just studying blo.od and stomach flows in sea spiders.”
He realized their hearts were only beating weakly and moving blood solely in the center of their bodies. Their intestines, on the other hand, displayed powerful and well-organized contractions.
‘My ‘aha!’ moment came when I realized that all that churning of blo.od and guts [in marine spiders] could not be for digesting but rather about moving respiratory gases around,’ Dr Woods explained.
Peristalsis is a phenomenon that occurs in humans as well, with waves of involuntary muscular contraction and relaxation. Its function in humans is to promote digestion by mixing up stomach contents and moving them through the intestines.
Because sea spiders must also get adequate oxygen through their bodies, their peristaltic waves are significantly greater than would be required for digesting.
‘The findings underscore the tremendous evolutionary range of responses to challenges that all animals face,’ stated Dr. Woods and his colleagues in their paper.
Future fossil discoveries may aid scientists in better understanding the origins of this unusual survival strategy. Sea spiders move slowly and deliberately across the ocean floor.
They consume by str.iking immobile creatures with their lengthy proboscises, such as sea anemones and sponges, then sucking up tissue softened by the spider’s digestive secretions.
Sea spiders lack gills and instead absorb oxygen by diffusion through their porous exoskeletons.
Most sea spiders are smaller than a fingernail, but gigantic species may grow to the size of dinner plates in the frigid, oxygen-rich seas near Antarctica. Dr. Woods and his colleagues made their findings on an Antarctic journey to investigate this phenomenon known as ‘polar gigantism.’
Polar animals, like huge sea spiders, have bigger bodies than their temperate or tropical counterparts, according to scientists.
This tendency poses a slew of fascinating concerns regarding how arctic creatures handle basic life functions, such as getting adequate oxygen into their bodies.
They arrived at these conclusions after conducting a series of tests and observations on 12 different marine spider species, including video microscopy of tracers in the creatures’ blo.od-like hemolymph and guts.