Ebi refers to a style of preparing shrimp in Japan. Traditionally, you prepare the shrimp by “butterflying” them- That means that they are split open from the bottom and laid out flat. Butterfly shrimp can be use on maki, but it was originally used on nigiri.
Odori ebi “dancing shrimp”) is a sushi delicacy of Japan, and a form of sashimi. The sushi contains baby shrimp (Pandalus borealis or Marsupenaeus japonicus) that are still alive and able to move its legs and antenna while being eaten.