invertebrate vs scaredy pants

invertebrate

noun

  • A spineless person; a coward. 

  • An animal without vertebrae, i.e. backbone. 

adj

  • Cowardly, uncourageous; lacking character. 

  • Lacking a backbone; without vertebrae. 

scaredy pants

noun

  • A coward. 

How often have the words invertebrate and scaredy pants occurred in a corpus of books? (source: Google Ngram Viewer )