Agnathan and Aquatic vertebrate

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

Aquatic vertebrate and agnathan are semantically related. In some cases you can use "Aquatic vertebrate" instead a noun "Agnathan".

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

Agnathan and aquatic vertebrate are semantically related. Sometimes you can replace term "Agnathan" with "Aquatic vertebrate", this terms are similar.