Amphioxus and Cephalochordate

Amphioxus noun - Small translucent lancet-shaped burrowing marine animal; primitive forerunner of the vertebrates.

Cephalochordate and amphioxus are semantically related. In some cases you can use "Cephalochordate" instead a noun "Amphioxus".

Cephalochordate noun - Fish-like animals having a notochord rather than a true spinal column.

Amphioxus and cephalochordate are semantically related. Sometimes you can replace term "Amphioxus" with "Cephalochordate", this nouns are similar.