Answer 1:
The human brain is a soft, spongy collection of
tissues
and nerve cells. The main thing that protects
the human brain is the bone of the skull encasing it.
Then, there are three layers of membrane, called
meninges that also aid in covering and protecting
the brain. The three layers are the dura
mater, arachnoid mater, and pia mater. The dura
mater is closest to the bone, the arachnoid is in
the middle and loosely surrounds the brain, and
the pia mater is closest to the brain and attached
to the spinal cord surface. Finally, the
cerebrospinal fluid, a clear body fluid, also
cushions the brain.
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Answer 2:
Depends on the animal; many have no protection.
Arthropods such as insects have their hard,
chitinous exoskeleton over their entire bodies,
including their brains, while vertebrates have a
skull of some kind (although it may be cartilage).
Snails and most worms have effectively no
protection.
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