Task: Sentence Expansion
Input (English): Sea urchins feed mainly on algae , but can also feed on sea cucumbers , and a wide range of invertebrates such as mussels , polychaetes , sponges , brittle stars and crinoids .
Output (English): Sea urchins feed mainly on algae , so they are primarily herbivores , but can feed on sea cucumbers and a wide range of invertebrates , such as mussels , polychaetes , sponges , brittle stars , and crinoids , making them omnivores , consumers at a range of trophic levels .