constructor.modelName

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  appName: 'Ember Twiddle'
});

models.animal.js

import Model from "ember-data/model";
import attr from "ember-data/attr";
import { belongsTo, hasMany } from "ember-data/relationships";

export default Model.extend({
  name: attr()
});

models.ape.js

import Model from "ember-data/model";
import attr from "ember-data/attr";
import { belongsTo, hasMany } from "ember-data/relationships";
import Animal from 'twiddle/models/animal';

export default Animal.extend({
  kind: attr()
});

models.box.js

import Model from "ember-data/model";
import attr from "ember-data/attr";
import { belongsTo, hasMany } from "ember-data/relationships";

export default Model.extend({
  animals: hasMany('animal', {polymorphic: true})
});

routes.application.js

import Ember from 'ember';

export default Ember.Route.extend({
  model() {
    const box = this.get('store').createRecord('box');
    
    box.get('animals').addObject(this.get('store').createRecord('ape', {
      	name: 'Bokito'
    	})
    );                         
    
    return  box;
  }
});

templates.application.hbs

<h1>{{model.animals.firstObject.name}}</h1> 
<h2>is an {{model.animals.firstObject.constructor.modelName}}</h2>

twiddle.json

{
  "version": "0.10.4",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "2.7.0",
    "ember-data": "2.7.0",
    "ember-template-compiler": "2.7.0"
  },
  "addons": {}
}