Experts warn invasive hammerhead worms secrete "nasty toxin" and can be a foot long. Here's what to know.

It might be Shark Week, but sharks aren't the only hammerheads to watch out for this summer. An invasive worm that packs the poisonous power of a puffer fish and the slithering stamina of a snake has been spotted along the East Coast of the U.S.

Michael Raupp, a professor of entomology at the University of Maryland, wrote about recent sightings of the worm in his "Bug of the Week" blog, saying "sometimes something so weird and creepy pops up that we need to spend some time on it." 

He describes hammerhead worms as "creepy, slithering, predatory flatworms" that "dine on unsuspecting earthworms" and other creatures.