Puffer and Plectognath fish

Puffer noun - Any of numerous marine fishes whose elongated spiny body can inflate itself with water or air to form a globe; several species contain a potent nerve poison; closely related to spiny puffers.

Plectognath fish and puffer are semantically related. In some cases you can use "Plectognath fish" instead a noun "Puffer".

Plectognath fish noun - Tropical marine fishes having the teeth fused into a beak and thick skin covered with bony plates or spines.

Puffer and plectognath fish are semantically related. Sometimes you can replace term "Puffer" with "Plectognath fish", this terms are similar.