The great barracuda's family tree

We can handily use the great barracuda as an example to illustrate levels of taxonomic or systematic organization, going from the specific (the great barracuda) to the general (all animals), to gain an appreciation of nature's complexity of relationships. This little trip also hints at the patience of those who, over the centuries, have attempted to impose a systematic pattern on those relationships. Each grouping is included by the group it precedes — for example, order Perciformes includes suborder Scombroidei as well as other suborders

Kingdom: Animalia
- all animals

Subkingdom: Metazoa
- all multicellular animals

Phylum: Chordata
- all animals that have a notochord (usually a dorsal rod) at some stage in their development. The three other chordate subphyla include obscure groups such as acorn worms and the better-known sea squirts, or tunicates, and amphioxus (well-known to generations of students)

Subphylum: Vertebrata
- all animals with a vertebral column

Superclass: Gnathostomata
- also includes grade Tetrapoda, that includes amphibians, reptiles, birds, and mammals . The only vertebrates not included in the Gnathostomata are the lampreys and hagfishes, that belong to superclass Agnatha)

Grade: Pisces
- includes only two living classes: Osteichthyes and Chondrichthyes (sharks and rays)

Class: Osteichthyes
- also includes lungfishes and the coelacanth

Subclass: Actinopterygii
- also includes the freshwater Chinese and American paddlefishes and sturgeons

Infraclass: Neopterygii
- also includes the freshwater gars

Division: Halecostomi
- includes all teleosts and one other species, the primitive freshwater bowfin (Amia calva)

Subdivision: Teleostei
- the teleost fishes — includes about 95% of the world's fish species. An extremely diverse group

Infradivision: Euteleosti
- 'true teleosts,' comprising 99% of teleost fishes. This group includes most teleosts except herrings and their cousins, eels, tarpon , and a few African and South American freshwater species)

Superorder: Acanthopterygii
- the most successful group in shallow seas, including coral reefs, totalling about half of all living fishes. In addition to Order Perciformes, this group includes the advanced puffers, flounders, and trunkfishes and others such as flying fishes , killifishes, silversides, squirrelfishes, seahorses, trumpetfishes, and scorpionfishes

Order: Perciformes
- includes the most evolutionarily advanced fishes, including most of those found on coral reefs. A sampling of representative taxa includes most of the fishes found on or near a coral reef: groupers, cardinalfishes, tilefishes, jacks, snappers, mojarras, grunts, porgies, goatfishes, chubs, spadefishes, butterflyfishes, angelfishes, sweepers, damselfishes, hawkfishes, wrasses, parrotfishes, jawfishes, blennies, clinids, dragonets, gobies, surgeonfishes, mackerels, tuna, and billfishes

Suborder: Scombroidei
- includes tunas and mackerels, as well as barracudas. Until 1994, barracudas were contained within the suborder Sphyraenoidei (a cozy monophyletic group that included only the barracuda family) but then they were moved to Scombroidei, suddenly going from being considered a fairly primitive fish to being a much more advanced fish. I didn't get up to speed on the shift until I wrongly stated that barracuda belonged in the suborder Sphyraenoidei during my oral examination for the PhD — hardly the best time to find out news like that. Although I'm happy that my favorite fishes are now 'advanced,' I can't help but wish for the good old days when they had their own suborder. This situation illustrates the fluid nature of taxonomy, especially at higher levels of organization.

Family: Sphyraenidae
- includes only one genus (another monophyletic group, known as a monogeneric family)

Genus: Sphyraena
- includes all barracuda species

Species: barracuda
- the species epithet for one species and one species alone: our friend, the great barracuda

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