Sea Spiders Pump Blood and Oxygen Through Their Guts, Not Heart

A peculiar species of arthropods living deep in the ocean surprises us with its anatomy. Sea spiders are not regular animals which pump blood through their heart. Instead, they use their guts to circulate the vital fluid through their bodies.

• Sea spiders do not pump blood through the heart.
• Instead, their guts work like blood vessels.
• These guts reach out to their legs and spread all over their body.

These weird sea spiders have different sizes. They can be a millimeter small, but can also reach the size of a plate. You can recognize them by the tiny torsos surrounded by six long and thin legs. These legs are more important than we would think, since they also contain their sexual glands and their guts. In fact, most of the organism’s activity takes place in those legs.

Their guts are different from those of most animals. They form branches all over the body and go down to each leg. Also, these guts resemble our circulatory system. They fill most of the empty spaces left in the body, and transport blood and oxygen to each organ.

Researchers were curious how these creatures transport oxygen, so they started studying sea spiders the size of a plate they found in Antarctica. They injected them with fluorescent chemicals, and looked how they were transported. Afterwards, they observed how their heart were beating weakly, but more contractions where present in their guts.

This looked interesting, so they lowered the oxygen levels and observed a further interesting behavior in the guts. Those contractions started becoming more intense, and they realized the guts played the role of heart in the bodies of the sea spiders. All the results have been published in the journal Current Biology.

The discovery is incredibly interesting, since it is the first instance of a gut-based circulatory system. This is a more efficient way to exchange gases and deliver oxygen to all organs. Now, researchers are wondering if any other unknown sea creatures are sharing the same mechanism.
Image Source: Wikimedia Commons