Answer:
The starfish Pisaster ochraceus is a keystone species in the rocky marine intertidal communities off the northwest coast of North America. This predatory starfish feeds on the mussel Mytilus californianus and is responsible for maintaining much of the local diversity of species within certain communities. A keystone species is an organism that helps define an entire ecosystem. Without its keystone species, the ecosystem would be dramatically different or cease to exist altogether. This means that if the species were to disappear from the ecosystem, no other species would be able to fill its ecological niche.
Explanation:
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Answer:
Oceanic crust is  younger crust . Well, It is because, an oceanic crust is formed when a continental crust undergoes a big tension crack due to the forces generated inside the earth, which may be because of the magma dwelling inside.  As the crack becomes prominent, the continent is broken into the segments with a big oceanic basin kind of structure between them (This takes millions and millions of years). Sediments deposit in the basin and get stratified to form the oceanic crust.  This is the reason that oceanic crust is younger than the continental crust.
 
        
                    
             
        
        
        
Answer:
to discover new things in life
 
        
             
        
        
        
Answer:
Persistent depressive disorder. 
Persistent depressive disorder, known as dysthymia or low-grade depression, is less severe than major depression but more chronic. It occurs twice as often in women as in men. Persistent depressive disorder (PDD) is a serious and disabling disorder that shares many symptoms with other forms of clinical depression.
 
        
             
        
        
        
Answer:tropical rainforest 
Explanation: Is wet and got