Dinoflagellate and Mastigophore

Dinoflagellate noun - Chiefly marine protozoa having two flagella; a chief constituent of plankton.

Mastigophore and dinoflagellate are semantically related. In some cases you can use "Mastigophore" instead a noun "Dinoflagellate".

Mastigophore noun - A usually nonphotosynthetic free-living protozoan with whiplike appendages; some are pathogens of humans and other animals.

Dinoflagellate and mastigophore are semantically related. Sometimes you can replace term "Dinoflagellate" with "Mastigophore", this nouns are similar.