Marine life is defenseless against microplastics, the tiny particles polluting our seas, which are not only orally ingested by these creatures but also enter their systems via their gills, according to a new study.

Scientists also discovered that when microplastics are drawn in through this method they take over six times longer to leave the body compared with standard digestion.

"Many studies on microplastics only consider ingestion as a route of uptake into animals. The results we have just published stress other routes such as ventilation," lead author Dr. Andrew Watts of Biosciences at the University of Exeter said in a statement.

"We have shown this for crabs, but the same could apply for other crustaceans, molluscs and fish - simply any animal which draws water into a gill-like structure to carry out gas exchange."

Watts and his colleagues also worry that the longer these microplastics stay within their system, the further up the food chain it will pass as predators consume their prey.

Using fluorescently labeled polystyrene microspheres, researchers showed how microplastics were retained in the bodies of the common shore crab (Carcinus maenas).

The images indicated that sticky, hair-like "setae" structures within the foregut of the crabs keep the microplastics trapped inside them.

Such possibly health-harming plastic pollution is becoming an increasing worry for scientists who fear that it's threatening the world's oceans.

It's not an outrageous concern, considering that the world used an estimated 288 million tons of plastic in 2013 - 10 percent of which supposedly ends up in the ocean.

"This is a human issue. We have put this plastic there, mostly accidently, but it is our problem to solve. The best way to do this is to reduce our dependency on plastic. It comes back to the old phrase: reduce, reuse and recycle," Watts added.

The study's findings were published in the journal Environmental Science and Technology, and funded by the collaborative research project CleanSeas.