Edit in JSFiddle

function Animal(species) {
    this.species = species;
}

// Create an accessor function on the prototype
Animal.prototype.getSpecies = function() {
     return this.species;   
}


function Dog(name, age) {
    this.species = 'dog';
    this.name = name;
    this.age = age;
}

// Chain the prototype back to Animal
Dog.prototype = Object.create(Animal.prototype);

// Make sure the Dog constructor is called on instantiation
Dog.prototype.constructor = Dog;

// Add a new function to the prototype
Dog.prototype.call = function() {
    console.log( "Here, " + this.name );
}

// Instantiate our new object
var myDog = new Dog('Fido', 4);

// Call each method on the object
myDog.call();
console.log(myDog.getSpecies());