Answer:
a keystone species
Step-by-step explanation:
A keystone species is a species that plays a key role in the balance of the entire ecosystem. Some examples of keynote species that are critical for their ecosystems include sharks, African elephants, sea otters, etc. The most important feature that defines a keynote species is the fact that these species have a huge influence on the food web dynamics. Moreover, keystone species are also characterized by a low functional redundancy (ie., they cannot be replaced by other species within the ecosystem).