These tiny water bears, called Tardigrades (meaning "slow stepper"), are water-dwelling, eight-legged, segmented micro-animals. They have been sighted from mountaintops to the deep sea, from tropical rain forests to the Antarctic.

Tardigrades are notable for being perhaps the most durable of known organisms; they are able to survive extreme conditions that would be rapidly fatal to nearly all other known life forms. They can withstand temperature ranges from 1 K (−458 °F; −272 °C) to about 420 K (300 °F; 150 °C), pressures about six times greater than those found in the deepest ocean trenches, ionizing radiation at doses hundreds of times higher than the lethal dose for a human, and the vacuum of outer space. They can go without foo ...

White bloods cells, known scientifically as leukocytes, are immune system cells that fight infect. The immune system is made up of a network of cells, tissues, and organs that work together to protect the body. Sometimes our bodies encounter pathogens like bacteria, or in this case a parasitic worm. Roundworms, or nematodes, are parasites that can infect people by living and feeding in the intestines. There are different kinds of worms that can cause infection, and they can range in length from 1 millimeter to 1 meter. Luckily, this worm was no challenge for these hungry white blood cells. ...