thin, dark line beneath the surface of the flesh.
Although people commonly call it a vein, it is not a blood vessel in the way many people imagine. It is part of the shrimp’s digestive system.
This distinction matters because a shrimp can have its shell removed while still having its digestive tract intact. Likewise, shrimp can be cooked with their shells on after the digestive tract has been removed.
In other words, shell-on shrimp are not automatically deveined, and peeled shrimp are not automatically deveined either.
The two processes
