Invertebrate and Shellfish

Invertebrate noun - Any animal lacking a backbone or notochord; the term is not used as a scientific classification.

Shellfish and invertebrate are semantically related. In some cases you can replace term "Shellfish" with "Invertebrate", this nouns are similar.

Shellfish noun - Invertebrate having a soft unsegmented body usually enclosed in a shell.

Invertebrate and shellfish are semantically related. Sometimes you can use "Invertebrate" instead a noun "Shellfish".