Most animals use the strong, steady beating of their hearts to move blood around their bodies and keep up the supplies of oxygen to the tissue that needs it. Not sea spiders: they pump their guts instead.
While the underwater arthropods do have hearts, they beat only weakly. This discovery, made by H. Arthur Woods of the University of Montana after spending “a lot of time just watching blood and gut flows in sea spiders” while stationed at McMurdo Station in Antarctica, led Woods to realise that the heart was only circulating blood in the small inner section of the creatures’ legs.
He had also noticed that the guts of the sea spider, which are complex and many-branched, extending down to the end of each leg, underwent frequent waves of peristaltic contraction much stronger than digestion would require.
After conducting a series of experiments and observations in 12 sea spider species, which involved video microscopy of tracers in the animals’ hemolymph and guts together with experimental manipulation of the guts’ ability to contract, Woods and his colleagues were able to confirm that the guts were in fact doing the heavy lifting of moving the blood around.
Strange as it may seem, the finding highlights how evolution often finds multiple ways to solve the same problem.
The research is published in Current Biology.
Originally published by Cosmos as Weak-hearted sea spiders use guts to pump blood
Read science facts, not fiction...
There’s never been a more important time to explain the facts, cherish evidence-based knowledge and to showcase the latest scientific, technological and engineering breakthroughs. Cosmos is published by The Royal Institution of Australia, a charity dedicated to connecting people with the world of science. Financial contributions, however big or small, help us provide access to trusted science information at a time when the world needs it most. Please support us by making a donation or purchasing a subscription today.