Evolution and systematics

The order Beryciformes encompasses 7 marine families, 29 genera, and about 140 species. The seven families are:

• Anomalopidae, the flashlightfishes or lanterneye fishes

• Anoplogasteridae (also spelled Anoplogastridae), the fangtooth fishes

• Berycidae, the alfoncinos and redfishes

• Diretmidae, the spinyfins

• Holocentridae, the squirrelfishes and soldierfishes

• Monocentridae, the pineapplefishes or pineconefishes

• Trachichthyidae, the roughies or slimeheads

The order Beryciformes falls at the base of a large grouping of fishes collectively known as percomorphs. These advanced fishes include the order Perciformes, which comprises a great diversity of fishes including cichlids, perches, blennies, and barracudas. Like all other percomorphs, the beryciforms have a characteristic linked arrangement of the pelvic and pectoral girdles. They differ from other percomorphs in the number of rays in the tail fin. Caudal rays in most percomorphs number 17, but fishes in the Beryciformes order have 18 or 19. Systematists believe that as the fishes advanced evolu-tionarily, the number of tail-fin rays decreased. The fact that the Beryciformes have a greater number of caudal rays places them at the base of the percomorph lineage.

At one time, the order Beryciformes was larger and included the beardfishes, whalefishes, gibberfishes, and prick-lefishes. Systematists once classified beardfishes as primitive beryciforms, but have now placed them in their own order, the Polymixiiformes, which precedes the evolution of the Beryciformes. The whalefishes, gibberfishes, and pricklefishes are in the order Stephanoberyciformes, and accompany the Beryciformes at the base of the percomorph lineage. The genera of beryciform fishes have also undergone some changes in classification. For example, the squirrelfishes have at one time or another been classified under the genera Adioryx, Flammeo, Holocentrus, Sargocentron, and Neoniphon, but the latter three are currently used.

The fossil record indicates that beryciform fishes occurred at least as far back as the late Cretaceous period, and were abundant. The group has persisted and is still quite common.

Betta Fish

Betta Fish

This is not another general fish hobby ebook you come across often. This ebook has valuable information that comes from years of research by many experience experts around the world who share the same interest you and me have..... Betta Fishes.

Get My Free Ebook


Post a comment