Final answer:
It is false that pink and black abalone sperm cross-fertilize each other's eggs, as abalones have specific mechanisms to prevent such cross-species fertilization.
Step-by-step explanation:
The statement that pink and black abalone spawn at the same time but their sperm do not cross-fertilize each other's eggs is false. Abalones generally have mechanisms to avoid such cross-species fertilization, commonly due to specific chemical cues on the surface of eggs that are recognized only by sperm from the same species. This specificity ensures that fertilization occurs only between the same species, which is important for maintaining species boundaries and avoiding the production of nonviable or less-fit hybrid offspring.
The statement that pink and black abalone sperm do not cross-fertilize each other's eggs is true. This is because pink and black abalone, despite spawning at the same time, have reproductive barriers that prevent their sperm from undergoing fertilization with the eggs of the other species. This may be due to differences in the proteins or molecules on the surface of their eggs and sperm, which can only recognize and bind to those of their own species.