Leviticus 11:8

All dead bodies defile. But it should be observed that contact with a living unclean animal did not defile. The ass e.g. was unclean for food, but was the common beast of burden among the Israelites.

9-12. Water animals. The condition of cleanness here is the possession of fins and scales. It follows that shellfish and eels are forbidden as food.

13-19. Birds. No signs are given to distinguish clean from unclean birds. The latter are specified, being mostly birds of prey and feeders on carrion.