Dictionary:

branchiopod

  (brăng'kē-ə-pŏd')

Any of various aquatic crustaceans of the class Branchiopoda, such as the fairy shrimp and water flea, characterized by a segmented body and flattened, leaflike thoracic appendages.

[From New Latin Branchiopoda, class name : Latin branchia, gills; see branchia + New Latin -poda, -pod; see –pod.]

The noun has one meaning:

Meaning #1: aquatic crustaceans typically having a carapace and many pairs of leaflike appendages used for swimming as well as respiration and feeding
  Synonyms: branchiopod crustacean, branchiopodan

The adjective branchiopod has one meaning:

Meaning #1: of or relating to or characteristic of the subclass Branchiopoda
  Synonyms: branchiopodan, branchiopodous
  Pertains to noun: subclass Branchiopoda (meaning #1)