Although muscle specialization has been studied extensively in vertebrates, less is known about the mechanisms that have evolved in invertebrate muscle that modulate muscle performance. Recent research on the musculature of squid suggests that the mechanisms of muscle specialization in cephalopods may differ from those documented in vertebrates. Squid muscles appeared to be cross-striated instead of striated like most other cephalopods.
Squid
Squid are part of the Mollusca phylum.