Answer:
Early land animals had both lungs AND gills, and their bodies consisted of few hard parts. Meaning they lacked things like an exoskeleton for instance. Animals today have either lungs OR gills and many have protecting hard parts of their bodies.
Explanation:
They hide in places like driftwood and vegetation
Mammal I’m not sure sorryyyy
Answer:
The areas that have had the action potential are refractory to a new action potential.
Explanation:
Hope this helps<3
