Periodic Table of Fishes

Summary

Fishes are vertebrates, and represent more than one-half of all living vertebrates, with currently about 28,000 species described. This complex diversity makes their phylogenetic relationships complicated. In order to understand and have fun with the classification and phylogeny of fishes, I constructed the "Periodic Table of Fishes". The "Periodic Table of Fishes" is based on the commonly known Periodic Table of Elements. In the Periodic Table of Elements, vertical columns are groups and horizontal rows are periods. In the "Periodic Table of Fishes", the group represents classification of fishes, and period represents phylogenetic relationships of fishes. Fishes have a long evolutionary history, estimated to have first appeared more than 400 million years ago. Each periodic element represents to a different fish species, with the initials of the fish name corresponding to the atomic symbol.^*1 Time of divergence is represented on the "Periodic Table of Fishes", with more ancient fishes illustrated on the left side or top of the table and more modern fishes illustrated on the right side or bottom.
^*1Relationship of atomic symbol and fish name: I placed Gasterosteus aculeatus for Ga (Gallium, atomic number 31), adopting the initial of its scientific name. On the other hand, I place Culaea inconstans for B (Boron, atomic number 5), which belongs to Gasterosteiformes in "Periodic Table of Fishes". Since there is no fish containing "B" for the scientific name in Gasterosteiformes, I used initial "B" of Culaea inconstans's common name "brook stickleback".

Relationship between Phylogeny of Fishes and Periodic Table of Elements

Fish classification in "Periodic Table of Fishes" is based on Nelson (2016). Phylogenetic relationship of fishes is clarified by recent molecular phylogenetic analyses. Phylogenetic relationship of fishes in "Periodic Table of Fishes" is based on the recent reports by Miya and Nishida (2009) and Nishida (2012).

Group 1 (Chondrichthyes, Sarcopterygii, and Basal Actinopterygii)

Gnathostomata is divided into two groups; Chondrichthyes whose skeletons are made of cartilage and Teleostomi whose skeletons are made of bone. While Chondrichthyes comprises roughly 1,000 species, Teleostomi comprises roughly 27,000 species. The former Chondrichthyes is placed at the top of Group 1. During evolution, the latter Teleostomi is subdivided into two groups; Sarcopterygii and Actinopterygii. Sarcopterygii comprised only 8 species,^*2 while the vast majority fishes belong to Actinopterygii. The latter group Actinopterygii is further divided into Basal Actinopterygii shown in Group 1, and the rest of the Actinopterygii are shown in Groups 2 through 18. Within Group 1, more ancient fishes appear at the top of column because their divergence time proceeds that of the fishes below them: Chondrichthyes (Period 1, ray), Sarcopterygii (Period 2, coelacanth; Period 3, lungfish), and Basal Actinopterygii (Periods 4-7, Chondrostei, Cladistia, and Holostei).
^*2Sarcopterygii include not only lobe-finned fishes (8 species), but also tetrapods (amphibian, reptile, bird and mammal), which comprise roughly 30,000 species.

Group 2 (Basal Teleostei)

After the Basal Actinopterygii branched off from the ancestor, the evolution of Actinopterygii produced Teleostei. Teleostei comprises roughly 26,000 species, representing more than 96% of all living fishes. The Teleostei is further divided into Basal Teleostei (Osteoglossomorpha and Elopomorpha) shown in Group 2, and the rest of the Teleostei are shown in Groups 3 through 18. Within Group 2, more ancient fishes appear at the top of the "Periodic Table of Fishes" because their divergence time proceeds that of the fishes below them: Osteoglossiformes (Period 2), Elopiformes (Period 3), and Anguilliformes and Saccopharyngiformes (Periods 4-7).

Group 3 (Otocephala and Euteleostei)

After Osteoglossomorpha and Elopomorpha branched off from the common ancestor, two groups, Otocephala (roughly 8,000 species) and Euteleostei (roughly 17,000 species), appeared. By placing Otocephala in Group 3 and Euteleostei in Groups 4-18, this major divergence event can be visualized by the overall shape of the "Periodic Table of Fishes". This phylogenetic pattern is analogous to the pattern of the Periodic Table of Elements, where Lanthanides and Actinides typically appear as separate rows below the rest of table.

Otocephala

During evolution, Otocephala is further divided into Clupeomorpha and Ostariophysi. The latter group contains more than one-half of freshwater fishes, such as carps and catfishes, and represents more than 96% of all living otocephalans.

Euteleostei

Euteleostei is the largest category of fishes. During the evolution of Euteleostei, a divergence event established the Salmoniformes and Esociformes (Groups 6 and 7) followed by a later event which established Osmeriformes (Group 8). These three orders are defined as Basal Euteleostei in the "Periodic Table of Fishes". After that, Neoteleostei appeared, and branched into Stomiiformes (Group 9), Aulopiformes (Group 11 Period 6), Myctophiformes (Group 10 Periods 6-7), and Lampriformes (Group 5). These orders are defined as Basal Neoteleostei in the "Periodic Table of Fishes". Then, Acanthomorpha (Groups 4 and 10-18) appeared, which is the largest superorder and contains roughly 89% of living euteleosts.

Stephanoberyciformes (Group 4) is traditionally considered to be composed of three families: Cetomimidae (red whalefish, Rf, Atomic Number 104), Mirapinnidae (tapeptail, Ti, Atomic Number 22, and hairlyfish, Hf, Atomic Number 72), and Megalomycteridae (bignoses). However, recent molecular analysis revealed that they are female, larvae and male, respectively, of a single fish family called Cetomimidae (Johnson et al., 2009). This means "they are all in the same family", in Japanese "Zenbu oyakodearu" (Zr, Atomic Number 40).

Diversity of Fishes

Relative number of species of the above mentioned four groups (groups of Chondrichthyes, Sarcopterygii, and Basal Actinopterygii, Basal Teleostei, Otocephala and Euteleostei) corresponds well with the relative number of all the living fishes. Therefore, "Periodic Table of Fishes" also provides overview of diversity of fishes.

Reference

1. Nelson JS, Grande, TC, Wilson MVH. 2016. Fishes of the World, 5th Edition. John Wiley & Sons, Inc.
2. Johnson GD, Paxton JR, Sutton TT, Satoh TP, Sado T, Nishida M, Miya M. 2009. Deep-sea mystery solved: astonishing larval transformations and extreme sexual dimorphism unite three fish families. Biol Lett., 5: 235-239.
3. Miya M and Nishida M. 2009. Phylogenetic relationship of fishes: Approach using mitochondria genomics. “Natural history of marine biology: How life evolved in ocean.” Edited by Nishida M. pp. 82-101 (in Japanese).
4. Nishida M. 2012. Osteichthyes. in “Dictionary of Evolutionary Study” Edited by Society of Evolutionary Studies, Japan. pp. 345-353 (in Japanese).