Sigh, you city people. X-men indeed.
Nightcrawlers are earthworms, Lumbricus terrestris to be exact. They are called nightcrawlers because they rise from their burrows to lay on the surface at night, in the moist, cool air. They are central to a robust ecosystem, providing enhanced soil structures more habitable to plant growth, and enhance nutrient recycling. They are a foodsource for several animals such as robin's, moles and hedgehogs.
Here's the real beauty of the nightcrawler - They are a big, slimy, fat, muscular worm that fits perfectly on a fishing hook. Bass, bluegill, crappy and catfish love them. My greatest fishing successes in freshwater have came from using nightcrawlers as bait.
To catch nightcrawlers, go out into your yard at night with a flashlight. Pan the flashlight over the ground surface, looking for the reflection of earthworm slime. When you spot a healthy looking specimen, approach with all the Kung-fu stealth and quiet you can muster. Nightcrawlers can sense the vibration of approaching footsteps with surprising accuracy, and will disappear into their holes if they feel you coming. If you make a mistake and the nightcrawlers all vanish, just move to a different part of the yard and continue your worm harvest. Return later, and the nightcrawlers will probably be back laying on the surface.
When you get within grabbing distance, reach out quickly and snag the nightcrawler in the palm of your hand. Get as firm a grip as your stomach can handle, because they are very slippery. Now apply firm but gentle pressure upward to ease the nightcrawler out of it's hole, without breaking the worm in half.
Keep your nightcrawlers in a styrofoam bait bucket with some dirt and wet leaves. Make sure you put them in a cool shady place. If you don't have a cool, shady place, then put them in your refrigerator (just don't freeze them).