Nov. 18, 2008 -- Spiders have been spotted on the space station. These creatures are welcome guests, though one of them is missing at the moment.

Spiders in space aren't new. Two arachnids named Arabella and Anita flew to Skylab in 1973. Scientists were curious to see how the spiders would react in weightlessness -- would their webs be different and how would they eat and sleep.

Spiders in your house may send you scurrying for a shoe but spiders in space are almost hypnotic, as they struggle to weave a symmetric web in zero gravity.

Experiments with insects are an easy way for teachers across the country to get students involved in hands-on science, which is the goal of sending these two spiders, and some butterflies, into orbit on the latest shuttle mission to the space station.

Spider One, on view in his box with clear windows, was busy spinning a very tangled web, but Spider Two appears to be AWOL. Or is he?

Flight director Ginger Kerrick says they are looking for him. "The way it was explained to me is that he is a backup spider and he has his own contained space on board and he had moved out of that area. We think he came out of his bedroom and is in the living room of his house."

Kirk Shireman, deputy shuttle program manager, says that while only one spider is visible, that doesn't mean the other is missing. 'We don't believe he has escaped the payload. I am sure we will find him spinning a web somewhere in the next few days."

Astronaut Sandy Magnus, the newest member of the space station crew, was asked how the visible spider was doing.

Mission Control: "Is it weaving an organized looking web or is it something neat to see?"

Magnus: "The web is more or less 3-dimensional and it looks like it is all over the inside of the box, more of a tangled disorganized-looking web than a 'Charlotte's Web' kind of web."

The spiders will return to Earth when the Space Shuttle Endeavour lands at the end of its 15-day mission later this month.