Maxillopoda is a diverse class of crustaceans including barnacles, copepods and a number of related animals. It does not appear to be a monophyletic group, and no single character unites all the members.[2]
With the exception of some barnacles, maxillopodans are mostly small,[3] including the smallest known arthropod, Stygotantulus stocki.[2] They often have short bodies, with the abdomen reduced in size, and generally lacking any appendages.[3] This may have arisen through paedomorphosis.[3]
Apart from barnacles, which use their legs for filter feeding, most maxillopodans feed with their maxillae. They have a bauplan comprising 5 cephalic segments, 6 thoracic segments and 4 abdominal segments, followed by a telson.[4]
The fossil record of the group extends back into the Cambrian, with fossils of both barnacles[5] and tongue worms[6] known from that period.
Five subclasses are generally recognised, although many works have further included the ostracods among the Maxillopoda.[2] Of the five groups, only the Mystacocarida are entirely free-living; all the members of the Tantulocarida, Pentastomida, and Branchiura are parasitic, and many of the Copepoda are parasites.
Maxillopoda is a diverse class of crustaceans including barnacles, copepods and a number of related animals. It does not appear to be a monophyletic group, and no single character unites all the members.
