section_path: Muscle fiber type evolution/Examples of muscle fiber variation in different animals/Invertebrates
section_name: Invertebrates
paragraph_text: Invertebrates
  
  American lobster, Homarus americanus, has three fiber types including fast twitch fibers, slow-twitch and slow-tonic fibers. Slow-tonic is a slow twitch-fiber that can sustain longer contractions (tonic). In lobsters, muscles in different body parts vary in the muscle fiber type proportions based on the purpose of the muscle group.