Can Human sperm fertilize animal eggs?We hear about animals producing human-like creatures, how do their ovules get fertilized by human sperm, is...

Well, the short answer is no. Both animals and plants have
evolved extensive mechanisms which prevent this from
happening.

First, sperm have to find their way to an egg.
In mammals, when the egg is released from the ovary it is surrounded by a loose group of
follicle cells. These cells release a chemical signal that the sperm swim toward. If the
signal is not correct, the sperm won't find the egg.

While
the sperm are swimming up the female's reproductive tract, ions that her body secretes
are absorbed into the sperm cells, causing internal changes that are referred to as
capacitation. In humans, capacitation takes 5 to 6 hours and must
be completed before the sperm can accomplish its next job, which is to penetrate the
zona pellucida, or egg coat. The zona pellucida has proteins that
are similar to the proteins used by the immune system, and these proteins make
cross-species fertilization nearly impossible.

Once the
sperm has successfully penetrated the zona pellucida, the acrosome
reaction allows the sperm to fuse with the membrane of the egg so that the
male's DNA can enter the egg cell. The acrosome reaction requires specific proteins that
again prevent hybridization between species.

In order for
cell division to occur and create an embryo, the paternal and maternal DNA must line up
- another block to hybridization, as DNA varies from species to species enough for this
to be unlikely to work.

An interesting side note is that
fertility clinics sometimes use enzymes to strip the zona pellucida away from hamster
eggs, and then use the stripped eggs to test human sperm for penetrating power. Although
healthy sperm can penetrate the hamster eggs in this case, the DNA alignment fails and
the fertilized eggs die without undergoing mitosis.