Why does this not cause a comma splice?

This sentence appeared on an SAT writing section

Healthy arctic marine mammals have a thick layer of fat beneath the skin, whereas tropical marine mammals have very few fat reserves in their bodies”

Why is this not considered a comma splice as they are both independent clauses connected by a comma without the use of a FANBOYS.


Solution 1:

Whereas is a conjunction. Two independent clauses may be joined with a comma and a conjunction.

https://dictionary.cambridge.org/dictionary/english/whereas?q=Whereas