Aquatic vertebrate and Jawless fish

Aquatic vertebrate noun - Animal living wholly or chiefly in or on water.

Jawless fish and aquatic vertebrate are semantically related. In some cases you can replace phrase "Jawless fish" with "Aquatic vertebrate", this phrases are similar.

Jawless fish noun - Eel-shaped vertebrate without jaws or paired appendages including the cyclostomes and some extinct forms.

Aquatic vertebrate and jawless fish are semantically related. You can use "Aquatic vertebrate" instead a noun phrase "Jawless fish".