God word specifies what we are to eat or not eat. Shrimp, lobster, crab are "cleaners of the sea" and according to the word we should not eat these creatures. We can eat creatures living in the seas that have fins and scales.
For the animals living on land we can eat any animal that has a divided hoof and chews the cud. Therefore, accordingly the pig and rabbit are not allowed. Obedience is key! Visit Leviticus 11 for more about clean and unclean foods.