Brine shrimp Artemia salina, copyright Hans Hillewaert.

Belongs within: Allotriocarida.
Contains: Calmanostraca, Diplostraca, Anostracina.

The Branchiopoda are a morphologically diverse group of crustaceans with phyllopodous limbs, including the water fleas, fairy shrimp and tadpole shrimp. The majority of species are found in fresh or brackish waters though a smaller number have entered fully marine habitats.

Within the Branchiopoda, a well-developed carapace is present in members of the clade Phyllopoda but absent in the Anostraca. Anostraca have eyes on mobile stalks whereas eyes are sessile in Anostraca (Ax 1999). The Anostraca, brine shrimps, typically inhabit saline habitats such as ephemeral pools and marine lagoons, and swim with their ventral side upwards. Brine shrimps may be divided between the clades Anostracina and Artemiina with the latter being characterised by two rigid wart- or spine-like outgrowths on the inner side of the median article of the second antenna in males, a short brood pouch often with two lateral lobes in females, and the seventh abdominal segment often being fused with the telson (Weekers et al. 2002).

Brine fairies
Published 24 September 2012
The once-ubiquitous ‘sea monkey’ advertisement. Take a very good look at the words in the lower margin.

Readers of a certain age (or readers who have perused the comic books once belonging to readers of a certain age) will instantly recognise the image above. It appeared on almost every comic book published between 1962 and 1975, and offered a something truly mind-blowing. For a couple of bucks, you could receive a small packet in the post that, when its contents were added to water, grew into minute fish-tailed humanoids that would create their own minute society, all in one goldfish bowl sitting in your bedroom!

As Robin Ince summed up the sea monkey experience in his Bad Book Club: ‘This was a lie’. You did receive a small packet in the post, the contents of the packet did hatch out in water, but you did not get the pictured anthropomorphs. What you actually got were these:

The North American brine shrimp Artemia franciscana, photographed by Jean-François Cart.

The ‘sea monkeys’ became labelled one of childhood’s great disappointments, which I call an utter shame. Because I personally would describe them as some of the most elegant crustaceans that I’ve ever seen.

Brine shrimp and their relatives belong to a group called the Anostraca. The Anostraca, sometimes referred to as fairy shrimps, are a group of a little under three hundred described species. They are generally less than an inch long, though the larger species can grow to several inches. The taxon name basically means ‘without a carapace’, and this is one of the distinctive features of the group. The body is elongate and, behind the head, is divided into a thorax bearing feathery swimming legs and an abdomen lacking appendages except a terminal pair of uropods. Most species of Anostraca have eleven pairs of swimming legs, though the species Polyartemiella hazeni and Polyartemia forcipata have, respectively, seventeen and nineteen pairs (Weekers et al. 2002). Anostracans have a distinctive slow swimming style, lying on their back. They are found living in ephemeral or hypersaline waters where predatory fish are few or absent; in order to persist in such environments, they produce resistant eggs that are able to survive drying out, hatching when the temporary pool is refilled by the rain.

Conservancy fairy shrimp Branchinecta conservatio, from here.

The phylogeny of Anostraca was investigated by Weekers et al. (2002), who found that they could be divided between two lineages: one including the genera Artemia and Parartemia, which are found in hypersaline waters, and the other containing the remaining freshwater genera. Most members of both lineages are filter-feeders, but some larger members of the freshwater lineage in the genus Branchinecta have become predators. The most favoured prey of these large Branchinecta? Why, smaller Branchinecta! Studied specimens of the predatory Branchinecta raptor would only deign to take other invertebrate prey if their preferred B. mackini was unavailable (Rogers et al. 2006). These predatory Branchinecta are found living in turbid, sediment-filled waters with low visibility, and mostly found their prey by coming into contact with it whilst swimming in the water column. Squeezing water out of a pipette near one would incite it to try and attack the pipette. If unable to find swimming prey, B. raptor would swim down to the sediment bed and stir it up, then attempt to find invertebrates flushed out of hiding.

Streptocephalus torvicornis, photographed by J.R. Casaña & Manolo Ambou Terradez.

The two hypersaline genera have complementary distributions: Parartemia is endemic to Australia while Artemia is found on the remaining continents (though Artemia is now present in some localities in Australia as an introduced taxon). In the past, all Artemia around the world were often treated as a single species, A. salina. However, the existence of a number of geographically distinct lineages has now been established, with these treated as separate species (A. salina proper is found in Europe). Both sexually and parthogenetically reproducing forms of Artemia exist. The parthenogenetic forms are treated as a single species, A. parthenogenetica, and derive from a single Eurasian origin, but are themselves genetically diverse, including diploid, triploid, tetraploid and pentaploid individuals (Triantaphyllidis et al. 1998). Sadly, this new-found taxonomic complexity of Artemia is in some danger of re-simplifying: the international trade in brine shrimp, used mostly as food for fish, is almost entirely based on eggs derived from the Great Salt Lake in Utah. As a result of this trade, the North American species A. franciscana has become introduced, both accidentally and deliberately, to saline waters around the world, and has been found in many localities to be replacing the native brine shrimp.

Systematics of Branchiopoda
| | i. s.: EstheriaB66
| | |--E. fukiensisG31
| | |--E. mangaliensisF71
| | |--E. newcombii Baird 1866B66
| | `--E. striata [incl. E. striata var. tateiana]T64
| | Ozestheria rubraSC17
| |--CalmanostracaMD01
| `--DiplostracaMD01
| i. s.: ProchiracephalusS02
| Chirocephalopsis bundyiD56
| Siphonophanes grubei [=Chirocephalus grubei]A99
|--Parartemia [Parartemiidae, Parartemiinae]WM02
| `--P. zietzianaWM02
`--Artemia Leach 1819BWW93 [ArtemiidaeWM02]
|--A. franciscanaWM02
`--A. salinaWM02

Branchiopoda incertae sedis:
Leptestheriella ineremisT06
Daphniopsis pusillaTDC06
Cyclestherioides lenticularis (Mitchell 1927) [=Estheria lenticularis]F71
Discoleaia discoidalis (Mitchell 1925) [=Leaia discoidea]F71
|--E. glabra (Mitchell 1927) [=Estheria glabra, Palaeolimnadia glabra]F71
|--E. glenleensis (Mitchell 1927) [=Estheria glenleensis, Palaeolimnadia glenleensis]F71
`--E. linguiformis [=Estheria linguiformis, Palaeolimnadia linguiformis]F71
Estherites wianamattensis (Mitchell 1927) (see below for synonymy)F71
|--T. belmontensis (Mitchell 1925) [=Leaia belmontensis]F71
|--T. etheridgei Kobayashi 1954F71
|--T. intermedia (Mitchell 1925) [=Leaia intermediata]F71
|--T. mitchelli (Etheridge 1892) [=Leaia mitchelli]F71
`--T. sulcata Kobayashi 1954F71
Quadrileaia quadricarinata (Mitchell 1925) [=Leaia quadricarinata]F71
|--L. bellambiensis (Mitchell 1927) [=Estheria bellambiensis]F71
`--L. belmontensis (Mitchell 1927) [=Estheria belmontensis, Pseudestheria belmontensis]F71
|--E. coghlani (Etheridge 1888) [=Estheria coghlani, Palaeolimnadia coghlani]F71
|--E. harveyi [=Isaura (Euestheria) harveyi]T61
| |--E. h. harveyiT61
| `--E. h. wellingtoni [=Isaura (Euestheria) harveyi wellingtoni]T61
|--E. ipsviciensis (Mitchell 1927) [=Estheria ipsviciensis, Pseudestheria ipsviciensis]F71
|--E. lata (Mitchell 1927) [=Estheria lata, Pseudestheria lata]F71
|--E. middendorfiiK84
|--E. novocastrensis (Mitchell 1927) [=Estheria novocastrensis, Pseudestheria novocastrensis]F71
|--E. obliqua (Mitchell 1927) [=Estheria obliqua, Pseudestheria obliqua]F71
`--E. trigonellaris (Mitchell 1927) [=Estheria trigonellaris, Pseudestheria trigonellaris]F71
Eulimene albida Risso 1826R26

Estherites wianamattensis (Mitchell 1927) [=Estheria wianamattensis, Euestheria wianamattensis, Palaeolimnadia wianamattensis]F71

*Type species of generic name indicated


[A99] Ax, P. 1999. Das System der Metazoa II. Ein Lehrbuch der phylogenetischen Systematik. Gustav Fisher Verlag: Stuttgart (transl. 2000. Multicellular Animals: The phylogenetic system of the Metazoa vol. 2. Springer).

[B66] Baird, W. 1866. Descriptions of two new species of phyllopodous crustaceans. Proceedings of the Zoological Society of London 1866: 122–123.

[BWW93] Briggs, D. E. G., M. J. Weedon & M. A. Whyte. 1993. Arthropoda (Crustacea excluding Ostracoda). In: Benton, M. J. (ed.) The Fossil Record 2 pp. 321–342. Chapman & Hall: London.

[D56] Dexter, R. W. 1956. A new fairy shrimp from western United States, with notes on other North American species. Journal of the Washington Academy of Sciences 46 (5): 159–165.

[F71] Fletcher, H. O. 1971. Catalogue of type specimens of fossils in the Australian Museum, Sydney. Australian Museum Memoir 13: 1–167.

[G31] Grabau, A. W. 1931. The Permian of Mongolia: A report on the Permian fauna of the Jisu Honguer limestone of Mongolia and its relations to the Permian of other parts of the world. American Museum of Natural History: New York.

[K84] Kobayashi, T. 1984. On the non-marine Mesozoic faunas of Asia and their bearing on the historical geology. Fossils 35: 33–37.

[MD01] Martin, J. W., & G. E. Davis. 2001. An updated classification of the Recent Crustacea. Natural History Museum Los Angeles County, Science Series 39: 1–124.

[R26] Risso, A. 1826. Histoire naturelle des principales productions de l’Europe méridionale et particulièrement de celles des environs de Nice et des Alpes maritimes vol. 5. F.-G. Levrault: Paris.

Rogers, D. C., D. L. Quinney, J. Weaver & J. Olesen. 2006. A new giant species of predatory fairy shrimp from Idaho, USA (Branchiopoda: Anostraca). Journal of Crustacean Biology 26 (1): 1–12.

[SC17] Schwentner, M., D. J. Combosch, J. P. Nelson & G. Giribet. 2017. A phylogenomic solution to the origin of insects by resolving crustacean-hexapod relationships. Current Biology 27: 1818–1824.

[S02] Sinitshenkova, N. D. 2002. Ecological history of the aquatic insects. In: Rasnitsyn, A. P., & D. L. J. Quicke (eds) History of Insects pp. 388–426. Kluwer Academic Publishers: Dordrecht.

[T61] Tasch, P. 1961. Paleolimnology: Part 2—Harvey and Sedgwick counties, Kansas: stratigraphy and biota. Journal of Paleontology 35: 836–865.

[T64] Tate, G. 1864. Description of a sea-star, Cribellites carbonarius, from the Mountain Limestone formation of Northumberland, with a notice of its association with Carboniferous plants. Report of the British Association for the Advancement of Science 33 (Notices and Abstracts): 88–89.

[T06] Timms, B. V. 2006. The large branchiopods (Crustacea: Branchiopoda) of gnammas (rock holes) in Australia. Journal of the Royal Society of Western Australia 89 (4): 163–173.

[TDC06] Timms, B. V., B. Datson & M. Coleman. 2006. The wetlands of the Lake Carey catchment, northeast Goldfields of Western Australia, with special reference to large branchiopods. Journal of the Royal Society of Western Australia 89 (4): 175–183.

Triantaphyllidis, G. V., T. J. Abatzopoulos & P. Sorgeloos. 1998. Review of the biogeography of the genus Artemia (Crustacea, Anostraca). Journal of Biogeography 25: 213–226.

[WM02] Weekers, P. H. H., G. Murugan, J. R. Vanfleteren, D. Belk & H. J. Dumont. 2002. Phylogenetic analysis of anostracans (Branchiopoda: Anostraca) inferred from nuclear 18S ribosomal DNA (18S rDNA) sequences. Molecular Phylogenetics and Evolution 25: 535–544.

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