Range Minimu Query: Given an array A[1,n] of n ordered objects (such as numbers), a Range Minimum Query (or RMQ) from i to j asks for the position of a minimum element in the sub-array A[i,j]. RMQs can be used to solve the lowest common ancestor problem.
The reasons that we do not eat or recommend shellfish are very similar. Shellfish are bottom feeders and feed on parasites and dead skin, many times from dead animals. They do not have appropriate digestive and filter systems to purify toxins and parasites from their body and flesh.
Same Species - Crayfish can and do eat each other. If the creatures are left for even a short while without any type of food, they will resort to cannibalism and attempt to eat each other. This is why turtle or fish pellets can be a good choice for food.