Why won't my point in Species class point to its heterogeneous class

My code consists of a class animal and 2 sub classes inheriting animal charactistics - amphibian, and fish. Everything in the code compiles apart from the Species* animal(&kermit); and animal = &nemo; - it says that "cannot convert fish* and amphibian* to species*. Where did i go wrong? i think there is something wrong with my conception of polymorphism here. Here is my code:

#include <iostream>
#include <string>
#include <vector>
using namespace std;

class Animal{
public: 
Animal(string name, string diet, bool queue)
: name_species(name), regime(diet), queue(queue){
    if(name == ""){cout << "Error, name can't be empty!" << endl; }
    else { cout << "A new animal" << endl; }}
virtual ~Animal(){ cout << "End of animal" << endl; }
virtual void display()const; 
protected:
string name_species; 
string regime; 
bool queue;     
}; 

void Animal::display() const{
cout << "I present the species " << name_species << endl;   
}

class Fish : public Animal {
public: 
Fish(string name, unsigned int scales, string diet = "Carnivore", bool  queue = true)
: Animal(name, diet, queue), scales(scales){ cout << "Add a fish" << endl; }
~Fish(){ cout << "Fish species " << name_species << " is turned off. " << endl; }
void display() const override; 
private: 
unsigned int scales; 
}; 
void Fish::display() const {
Animal::display(); 
if(queue == true){cout << "I have a tail "; } 
else { cout << "I don't have a tail "; } cout << "and i follow " << regime <<    endl; 
cout << "I have " << scales << " scales" << endl; }


class Amphibian : public Animal {
public: Amphibian(string name, string diet, unsigned int claws = 4, bool queue = false)
: Animal(name, diet, queue), claws(claws){ cout << "Add an amphibian" << endl; }
void affiche() const; 
~Amphibian(){ cout << "Amphibian species " << name_species << " is turned off. " << endl; }
private: 
unsigned int claws; 
}; 

void Amphibian::display() const {
Animal::display(); 
if(queue == true){ cout << "I have a tail "; }
else { cout << "I don't have a tail " ; } cout << "and i follow " << regime << endl;
cout << "I have " << scales << " scales " << endl;  }

class Species {
public: 
virtual void display()const = 0; 
virtual ~Species();
private:
vector<Animal*> animals;  
}; 

void Species::display()const{
for(size_t i(0); i < animals.size(); ++i){
    animals[i]->display(); }
}

Species::~Species(){ for(size_t i(0); i < animals.size(); ++i){
delete animals[i];}}

int main()
{
 Amphibian kermit("lizard", "insects");
 Fish nemo("dolphin", 6);
 Fish sala("salamander", 4);

 Species* animal(&kermit);
 animal->display();

 animal = &nemo;
  animal->display();

  return 0;
 }