Before I answer your question, I’ll elaborate on a few premises.
It needs to be appreciated that the Almighty has blessed man
with guidance in two ways. One of them can be termed as Innate Guidance
and the other one as Divine Guidance.
as the sphere of Innate Guidance is concerned, it is known that man has
been given certain faculties and abilities which are enough to guide him in
deciding the right course of action. He does not basically need any external
guidance in this regard. For example, his conscience very ably guides him about
good and evil.
second sphere of guidance, Divine Guidance, generally pertains to areas
where human beings are unable to decide the right course by themselves. It is in
order to complement and supplement the sphere of Innate Guidance that the
Almighty has divinely guided man through His Prophets. The Qur’ān and
Sunnah (the established religious practice of the Prophet (sws)) are the
only original sources of Divine Guidance.
As far as edibles are concerned, Divine Guidance has
prohibited some distinct types of food because they negatively influence the
inner purification of a person. The rest has been left to human nature to decide
for itself in view of the Innate Guidance it possesses. Man knows for
himself that beasts like lions and dogs and birds like eagles and vultures are
not meant to be eaten. There may be slight differences in this sphere, but
generally the dividing line is quite clear.
In the light of this principle, a Muslim can eat crabs or a
lobster if he does not feel an aversion to them. In other words, he himself must
decide on this issue since we have no explicit prohibition in Divine Guidance on these types of foods.