Branchiopoda (, , Laevicaudata,

Spinicaudata, Cyclestherida) D C Rogers, EcoAnalysts, Inc., Woodland, CA, USA ã 2009 Elsevier Inc. All rights reserved.

Introduction separated into the suborders Artemiina and Anostra- cina (Table 2). Artemiina contains two halobiont The extant members of the are monogeneric families: Artemiidae and Parartemiidae, arguably the most primitive living . Strictly commonly called ‘brine .’ Anostracina has for purposes of convenience with absolutely no basis in six primarily freshwater families commonly referred , they are divided into the so-called ‘large to as ‘fairy shrimp’: (monogeneric), branchiopods’ (fairy shrimp, , and tadpole , (six genera), Streptocephalidae shrimp) and the cladocerans (often called water ) (monogeneric), (six genera), Tanymas- (Table 1). Morphological, paleontological, and molecu- tigidae (two genera), and (ten genera). lar data suggests that the split off from the Male genitalic morphology defines the anostracan Spinicaudata early in the group’s history, as paedo- genera. Due to their soft bodies, anostracans are nearly morphic clam shrimp. The moniker ‘large’ branchio- unknown from records; the only definitive pod is a misnomer, in that, many so-called ‘large’ are from the Miocene. Fossils of now extinct near branchiopods are smaller than some cladocerans relatives are known from the (the (Figure1 ). Lipostraca) and the (Rehbachiella). The large branchiopods are found in temporary Molecular phylogenetic studies have been con- and saline inland aquatic on all continents ducted on anostracans, primarily defining the families including . The Anostraca and most clam and genera. Recent revisions include the Streptoce- shrimp are part of the planktonic component of tem- phalidae, Thamnocephalidae, and portions of the porary pools, playas, and salt lakes. Notostraca and Chirocephalidae. some clam shrimp are typically found at or near the Phyllopoda comprises three orders: Notostraca, bottom of temporary pools, lakes, and playas. These Laevicaudata, and (Table 3). The Notos- crustaceans are used as indicators of aquatic ecosys- traca (tadpole shrimp, shield shrimp, helmet shrimp) tem health, several are afforded protection contains one with two (possibly three) genera. under environmental law, and some species are eco- The has 12 described species and nomically important. As obligate aquatic macroinver- subspecies, and the genus has five. Triops can- tebrates, large branchiopods are important links in criformis may represent a separate genus, and prelim- the aquatic chain of ephemeral . Their inary molecular analyses suggest the presence of presence and persistence in ephemeral wetlands (some- many cryptic Triops species. The Notostraca have times occurring in the hundreds per cubic liter of water) been called ‘living fossils’ due to their minimal overall can serve as a biological indication of aquatic eco- morphological variation since their divergence over system health, which ultimately reflects on land-use 250 Ma. The associated lineage Kazakarthra, typi- practices from a larger landscape perspective. cally treated as a distinct order from the Notostraca,

became extinct sometime in the late . Taxonomy The Laevicaudata are a unique order of clam shrimp, The class Branchiopoda contains the fairy shrimp, tad- containing one family () with three genera pole shrimp, clam shrimp, and water fleas. Molecular and 37 species. Laevicaudata has been treated as a sub- and morphological studies support the monophyly of order of the Diplostraca, although evidence indicates the class, subclasses, and orders. Strong sexual selec- that the group represents a unique order. The Laevicau- tion has resulted in most anostracan species being data, Spinicaudata, and Cyclestherida are commonly well-defined morphologically, whereas the remaining referred to as ‘clam shrimp’ and often as the ‘Conchos- groups with , parthenogens, and gono- traca,’ although this term has lost all taxonomic mean- chory have converged morphologically, making species ing and has not been considered valid since the 1980s. difficult to define. Molecular analyses and morphological cladistic The Branchiopoda is divided into two extant sub- analysis place the Laevicaudata as a lineage older classes: Sarsostraca and Phyllopoda (Table 1). Sarsos- than the remaining diplostracans, more closely allied traca contains the single extant order Anostraca with to the Notostraca. No molecular analyses have been around 300 species (fairy shrimp and ), conducted within the Laevicaudata.

242 Encyclopedia of Inland Waters (2009), vol. 2, pp. 242-249

Invertebrates _ Branchiopoda (Anostraca, Notostraca, Laevicaudata, Spinicaudata, Cyclestherida) 243

‘Cladoceromorpha.’ The diplostracan typi- The Diplostraca is divided into three suborders: Spinicaudata, Cyclestherida, and Cladocera. The cally has an umbone and growth lines, and Cladocera are treated separately and are often com- and fossils have been misidentified as true clams. The bined with the Cyclestherida into a called the Cyclestherida contains two species (one is probably

an immature form of the type species), from the tropi- cal and subtropical regions of the world, occurring in Table 1 Higher classification of branchiopod Crustacea permanent and temporary waters.

The Spinicaudata has around 200 described spe- Class Branchiopoda Subclass Sarsostraca cies, however, the group is in need of revision. The

Order Anostraca Spinicaudata has three families; , Lep-

Suborder Artemiina testheriidae, and . However, the only

Suborder Anostracina character separating the and Cyzi- Subclass Phyllopoda cidae is the presence of the leptestheriid rostral Order Notostraca spine. This spine is present in some cyzicids, so the Order Laevicaudata Order Diplostraca two families may be united at some point in the Suborder Spinicaudata future. Cyzicidae contains four described genera, Suborder Cyclestherida (Combined with the Cladocera Leptestheriidae contains three, and Limnadiidae

into the ‘Cladoceromorpha’) contains five. The Spinicaudata are found on all Suborder Cladocera continents, except Antarctica.

Figure 1 Representative ‘large’ Branchiopoda. (a) Anostraca, ‘fairy shrimp’ buchananensis lateral view of entire ; (b) Notostraca, ‘tadpole shrimp’ carapace of Lepidurus viridis; (c) Laevicaudata, ‘clam shrimp’ lateral view of entire animal, with left half of carapace removed; (d) Diplostraca, Spinicaudata, ‘clam shrimp’ lateral view of .

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244 _ Branchiopoda (Anostraca, Notostraca, Laevicaudata, Spinicaudata, Cyclestherida)

Table 2 Anostracan families and genera Table 3 Phyllopod families and genera

Subclass Sarsostraca Subclass Phyllopoda Order Anostraca Order Notostraca Suborder Family Triopsidae Triops Artemiina Lepidurus Family Artemiidae Artemia Order Laevicaudata Parartemiidae Family Lynceidae Suborder Lynceiopsis Anostrocina Paralimnetis Family Branchinectidae Order Diplostraca

Thamnocephalidae Thamnocephalus Suborder

Carinophallus Spinicaudata Phallocryptus Family Gurneya Limnadiidae Limnadopsis Dendrocephalus Limnadia Branchinella Streptocephalidae Metalimnadia Branchipodidae Australobranchipus Branchipus Family Leptestheriidae Leptestheria Metabranchipus Maghrebestheria Pumilibranchipus Eoleptestheria

Rhinobranchipus Family Cyzicidae

Tanymastigidae Tanymastix Eocyzicus Tanymastigites Baikalolkhonia Chirocephalidae Branchinectella Sewellestheria Artemiopsis Suborder Parartemiopsis Cyclestherida Family Galaziella Cyclestheriidae Cyclestheria Suborder Cladocera Polyartemia

Polyartemiella

as adults and laevicaudatans range from 4 to 14 mm. Cyclestheridians are never more than 7 mm, and spi- The earliest fossil spinicaudatan clam shrimp come nicaudatans are typically 4–10 mm, although the from marine sediments in the Devonian. Also from genus Limnadopsis may reach 3 cm. the Devonian is a fossil branchiopod called Castra- The branchiopod cuticle is thin and is comprised of collis wilsonae , with a morphology that is intermedi- proteins and lipids impregnated with , with no ate between Spinicaudata and Notostraca. calcification, and little sclerotization. Adult branchio- pods retain the reduced first antennae of the larvae, however, the second antennae are only used for pro- pulsion in adult Diplostraca. In anostracans, the sec- Morphology ond antennae are robust, and in males are secondarily The Branchiopoda are separated as a distinct class of divided into two antennomeres, variously ornamen- Crustacea based primarily on the form of the larvae, ted, and modified into claspers to amplex the female which eclose as a nauplius or metanauplius. The larvae prior to copulation. In notostracans and laevicauda- have reduced, undifferentiated first antennae, the sec- tans, the second antennae are reduced, sometimes ond antennae are elongated and used for swimming, lost entirely in the Notostraca. and themandible is uniramous. One or more segments The head is proportioned to the body in anostra- and limb pairs are added with each molt. cans, notostracans, and spinicaudatans, but is mas- Branchiopods range in size from a few millimeters sive in the laevicaudatans, and may be larger than the to 17 cm. Anostracans are typically 1–5 cm in length, rest of the animal. A rostrum is absent in anostracans however, Dendrocephalus alachua and Branchinella and notostracans. Both the Notostraca and Laevicau- nana are both around 6 mm in length, while Branchi- data have a cephalic pore adjacent to the . necta gigas and Branchinecta raptor may reach The nauplii have a single median , which is 17 cm. Notostracans range from 1 to 10 cm in length reduced in most adult large branchiopods, but in the

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Invertebrates _ Branchiopoda (Anostraca, Notostraca, Laevicaudata, Spinicaudata, Cyclestherida) 245

Notostraca becomes a large tubercle on the nuchal As in the Laevicaudata, the male Cyclestherida have organ, behind the eyes. The adult compound eyes are the first pair modified as claspers, but in the Spinicau- fused in laevicaudatans and spinicaudatans, but are data the first two pairs are modified as claspers. separate and borne on stalks in anostracans. The claspers are formed from the endites, however,

The nuchal organ or dorsal organ may be involved the claspers are formed from different endites than in in ion transport. This organ lies on the dorsal surface the Laevicaudata. Females carry the between the of the head, although in the spinicaudatan family elongated exopods of the thoracopods, and the cara-

Limnadiidae it is borne on a short stalk. pace. In the Cyclestherida, the eggs hatch and the A head shield of some sort is present in the larvae, larvae undergo partial development in the space although in anostracans it is lost in the post naupliar between the female dorsum and the carapace, as in stages. Notostracans have a broad carapace covering the Cladocera. the head and , armed posteriorly (and occasion- The thoracopods are lamellar, each bearing a lateral ally dorsally) with stout spines. The Laevicaudata have pre-epipodite that has osmoregulatory functions. Bran- a broad carapace as juveniles similar to the Notostraca, chiopod limbs typically consist of a basal protopod, but this eventually divides into a true bivalved cara- with one or two pre-epipodites, an epipodite, an pace, with a dorsal, grooved true hinge that does not exopodite, an endite, and several endopodites, the form an umbone, and covers the entire animal. Growth proximal two being fused in the Anostraca. The name lines are never present, and the carapace is subspherical ‘branchiopod’ literally means ‘ foot,’ as it was once in shape. In the Diplostraca, the carapace folds over thought that the thoracopods were also . It is now the body, never developing a true hinge. With each known that the entire body functions as a gill. molt, spinicaudatans and cyclestheridians add a growth The is elongate and cylindrical in anos- line to the carapace margin. tracans and notostracans, ending in a with a A labrum lies over the mouth, which contains a pair terminal anus, flanked by a pair of cercopods. The of rolling type mandibles, which may also bite in anostracan abdomen is appendageless, but may be predatory anostracans. Some taxa have a reduced ornamented with spines, or protrusions. The notos- mandibular palp. Posterior to the mandibles are the tracan abdomen may bear numerous pairs of serially first and second maxillae, although the second maxil- homologous limbs, with several pairs per body seg- lae may be reduced or lost in anostracans. Functioning ment. Notostracan abdominal segment chitinized maxillary glands are present in larvae and most cuticular sections may wrap around the body two or anostracans. more times, distorting the number of body rings. The thorax is elongated and has the thoracopods The abdomen of the Laevicaudata is reduced to a and external reproductive organs. In anostracans, single anal somite bearing the anus and paired fila- there are 11 pairs of thoracopods (reduced to 10 in ments, but no . In the Spinicaudata and most female Parartemia, and increased to 17 in Poly- Cyclestherida, the abdomen is represented by a large artemiella and19inPolyartemia). Posterior to the chitinized telson with a terminal anus, large caudal last pair of locomotor thoracopods, are limbs modi- furcae, and a pair of terminal filaments. No appen- fied for . In males they are modified as dages other than the furcae are present. paired, semiretractable , and the females as a single ventral . Notostracans also have 11 segments comprising the Ecology thorax, the eleventh pair modified for reproduction, with a modified basis forming a brood pouch in females and hermaphrodites. Notostracans may have from 20 to 80 pairs of trunk limbs. Large branchiopod crustaceans are a component of

Laevicaudatan males have 10 thoracomeres and the zooplanktonic community within episodic, ephem- females 12, all bearing thoracopods. Male first - eral aquatic habitats, often occurring in densities of acopod endites are modified into claspers to amplex 200 individuals per liter of water or more. Most large the female prior to mating. In the genera Lynceiopsis branchiopods need drought to dry the resting eggs and and Paralimnetis , the second pair may also be prevent them from fungusing. Typical habitat for large modified, but not as claspers. Females carry the eggs branchiopods include vernal pools, seasonally ponded between the enlarged exopods of the thoracopods and areas within vernal swales, seasonal wetlands, tundra a set of lateral lamellae projecting from the trunk. pools, alpine pools, rock outcrop ephemeral pools These lateral lamellae are unique to the Laevicaudata. (tinajas, gnammas), clay flats, salt lakes, playas, and Spinicaudata and Cyclestherida will vary from 16 to alkali flats. The diapausing eggs lay dormant in or on 32 thoracomeres, each bearing paired thoracopods. the substrate during the dry and/or frozen stages of

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246 Invertebrates _ Branchiopoda (Anostraca, Notostraca, Laevicaudata, Spinicaudata, Cyclestherida) the habitat phenology, hatching when liquid water is debt. Large heat shock proteins have been present. isolated from Artemia eggs, but the exact role of the Some species occur in pools that never become protein is not entirely understood. Most large bran- completely dry (Streptocephalus sealii, Lynceus bra- chiopod eggs are resistant to desiccation, the chyurus, ), occurring in permanent acids and enzymes of predators, freezing, and pro- salt lakes, fishless permanent pools, or wetlands that longed burial, remaining viable even under anoxic con- dry to damp soil. In the arctic tundra and on the ditions for decades, possibly even centuries. Shrimp

Antarctic Peninsula, there are pools that never dry, eggs subjected to boiling water, freezing in liquid nitro- freezing solid in the winter, with anostracans and gen, and even exposed to the vacuum of space during a notostracans hatching when the pools melt each U.S. Space Shuttle Mission were still viable. spring. Other large branchiopods live in habitats that When habitat occupied by large branchiopods may remain completely dry for several years or even inundates from seasonal rainfall, rising water tables, decades (Branchinella, Thamnocephalus, Triops sp.). snowmelt, or runoff, some of the eggs hatch, and the Pool volume is important to some taxa. Many spe- nauplii swim into the upper water column. Beyond cies are found in larger temporary pools because inundation of the habitat, the specific cues for hatch- deeper pools with a large surface area can more easily ing are unknown, although temperature and conduc- maintain their dissolved oxygen levels. These habitats tivity are believed to play a large role. Rhodopsin is may last for several months and are often used by the present in the eggshell, and when triggered by an Chirocephalidae, Artemiidae, Parartemiidae, some outside energy source after wetting, moves to the lynceid clam , and the notostracan genus embryo, which then becomes active. Lepidurus . Conversely, some species complete their Only a fraction of each clutch hatches with cycle (egg to adult with eggs) in habitats that each pool inundation. This is a ‘bet-hedging’ strategy, last 3–5 days (Branchipodidae, Branchinectidae, and in that if all the eggs were to hatch and the habitat Streptocephalidae). Most species are found in tempo- dried before the shrimp could reproduce, then the rary habitats that last from 15 to 40 days. population would be eliminated. Since only a fraction Various physiochemical factors have been exam- hatches, a given habitat can fill and dry numerous ined in branchiopod habitats including alkalinity, times with a hatch of shrimp each time. total dissolved solids (TDS), and pH. However, the The maturation rates of the animal vary extensively importance of many of these parameters may be mini- depending upon temperature and habitat. Some mal, as the type and amount of dissolved salts may be Branchipodopsis, Branchinecta, and Streptocephalus a more important habitat requirement. Considering can mature in 3–6 days, whereas Triops, Lepidurus, the daily fluctuations in pH of a given habitat, this Cyzicus, Artemia, Chirocephalus, and others may is to be expected. During the daylight hours, hydro- take 18 days or longer. phytes (if present) are photosynthesizing, removing Reproduction may be sexual, parthenogenic, or the CO2 (from HCO3) from the water, and raising gonochoric. Spinicaudatan clam shrimp populations the pH. During the night, the hydrophytes are respir- commonly have protandrous hermaphrodites. Notos- ing, increasing the CO2 (and thereby, the HCO3)in tracans are typically parthenogenic or gonochoric, the water lowering the pH. If there is rainfall, the but some species with separate do occur. distilled precipitation will lower the pH, as will In anostracans, sexes are separate, except for a few winds that cause surface action. When the habitats parthenogenic Artemia species and possibly one are drying and losing volume through evaporation, Streptocephalus, in which males are rare or absent. the pH, alkalinity, TDS, and electrical conductivity Typical anostracans have a highly coadapted mate will increase, just as they decrease when the pools recognition system, wherein the male displays his inundate or reinundate. As a result, most large bran- enlarged and ornamented second antennae and chiopods are osmoconformers, with salt lake species antennal or cephalic appendages (if any) to the being hypo-osmotic regulators. Some taxa (some female. If the female does not swim away, the male Branchinecta and Branchinella) are capable of both. approaches the female from beneath and behind,

and amplexes the female with the enlarged second antennae. Amplexus occurs either between the last Life History pair of thoracopods and the brood pouch in a Large branchiopod eggs are released, deposited, or specialized amplexial groove, or on the brood pouch retained in the body of the parent. Typically, the eggs itself. Many families (Chirocephalidae, Branchipodi- are subjected to drying, freezing, or both in their envi- dae, Tanymastigidae, Parartemiidae) have a unique, ronment, often at extreme temperatures. Eggs kept species-specific ‘lock-and-key’ complimentary cou- in anoxic conditions for years show no evidence of pling between the ornamentation of the male second

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Invertebrates _ Branchiopoda (Anostraca, Notostraca, Laevicaudata, Spinicaudata, Cyclestherida) 247 antennae and the female amplexial groove, the result lipids (probably linked to carotenoid pigments) that of sexual selection. would otherwise be expended by the host during Amplexus may be sustained for a second or two reproduction. with rapid mating and release (Branchinectidae, No specific bacterial, viral, or protozoan diseases

Thamnocephalidae), or may last for hours or even have been reported from large branchiopods. Occa- days (Artemiidae, Parartemiidae, Chirocephalidae). sionally, specimens with black markings or lesions The female typically sheds her eggs as the shell will appear in collections. These black markings, forms over the fertilized oocytes, and the eggs fall to sometimes referred to as ‘black disease,’ are actually the substrate, or are retained (Artemiopsis). evidence of the normal immune response of all Crus- Predator consumption of branchiopod eggs aids in tacea to any , where any foreign bacteria is population distribution. Predators (e.g., birds, amphi- infused with melanin to lethal levels. Branchiopod bians, ) expel viable eggs in their excrement, often crustaceans are commonly found with phoretic ciliate at locations other than where they were consumed. protozoan colonies, which are abandoned on the If conditions are suitable, these transported eggs may exuvium with each molt. hatch at the new location and potentially establish new populations. Eggs are also transported by wind, Conservation Issues and in mud carried on the feet of , including livestock (or biologists) that wade through the habitat. Of the nearly 500 described species of large branchio- The vast majority of large branchiopods are omni- pods, more than one-fourth are known only from vorous filter feeders, indiscriminately filtering parti- their type localities, and several species have only cles from the water column, including bacteria, been collected once or twice. Many species are on unicellular , and micrometazoa. Most branchio- the International Union of Conservation of pods will attempt to consume whatever material they and Natural Resources’ Red List, and 20 or so are filter from the water column and can fit into their food listed as rare, threatened, or endangered at either groove, and do not discriminate based upon taste, as state or federal levels in the United States. , do some other groups. Anostracans, laevi- Austria, and other nations have species protected caudatans, and spinicaudatans will also rasp periphy- under law as well. The first large branchiopod pre- ton from rocks, sticks, stems, and slender leaves. serve was established in Austria in the 1990s to pro- Notostracans will filter feed, but as adults are more tect the Anostracan Chirocephalus shadinii. Similar typically omnivorous, with a strong preference for ani- preserves have developed in the United States and mal matter, and will capture and consume live inverte- Brazil. brates, amphibian larvae, or carrion. The Notostraca Habitat occupied by large branchiopods typically and some species of Branchinectidae are often preda- exists on level open ground. This geomorphic setting tory, and the anostracan Branchinecta raptor is an tends to be the most desirable for agricultural, urban, obligate predator as an adult. or industrial development. The greatest threat to ephemeral invertebrates is the elimination or modification of their habitat by development. Trophic Relationships The filling of ephemeral wetlands or modification of Large branchiopods are typically a component of a the watershed that supports those pools either elim- larger community structure. This inverte- inates the habitat or disrupts the pool ecosystem to brate community includes mostly planktonic Crustacea where it is overcome by opportunistic species that out dependent on temporary wetlands including , compete the obligatory ephemeral wetland species. cladocerans, and , as well as turbellarians, Damage to the watershed that supports temporary and a suite of species. wetlands will impact temporary wetland invertebrate

Large branchiopods can occur in high densities and communities. Elimination of the watershed will not are readily filtered from the water by ducks, flamin- allow the wetlands to pond properly and will curtail goes, avocets, and other wading birds. , storks, the movement of nutrients into the wetland. Road and cranes, as well as shrews, amphibians, and tempo- runoff entering the watershed and conveyed to occu- rary water fish (Galaxia, Cyprinodontids) will all con- pied habitat through the watershed may carry petro- sume large branchiopods. leum by-product residue or sediment from vehicles, Being prey items of birds, large branchiopods are paving, or road maintenance activities. Furthermore, an intermediate host for avian cestodes. Anostracans pesticide, herbicide, fertilizer, and sediment runoff that are hosting a cestode tend to be bright in from agricultural activities may enter the watershed color. The cestode cysticercoides castrates the anos- and be conveyed to the occupied habitat and may tracan host, causing the shrimp to accumulate be injurious to seasonal pool invertebrates. Ground

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248 Invertebrates _ Branchiopoda (Anostraca, Notostraca, Laevicaudata, Spinicaudata, Cyclestherida) disturbance from development activities may loosen shrimp Leptestheria compleximanus is used as a pet soil that that could enter the watershed and be con- food in Me´xico. In Thailand, local peoples consume veyed to habitat as sediment. paste made from the fairy shrimp Streptocephalus Nonnative invasive species are a threat to tem- sirindhornae reared in . porary wetland invertebrate communities. Invasive Artemia is frequently sold by the pet industry as Artemia populations are becoming established in ‘ Monkeys’ and the tadpole shrimp Triops is sold Western Australian salt lakes, competing with the as a ‘.’ As a result, large numbers of pet endemic Parartemia. In addition, people may introduce owners who keep Artemia or Triops have formed nondiscriminating predatory fish into temporary wet- clubs and internet chat rooms. Unfortunately, some land to control perceived local mosquito problems. have begun shipping eggs overseas to other collec- Habitat fragmentation is a threat to wetland inver- tors, raising the possibility of new invasive species tebrates in that the development surrounding small concerns. Conversely, this trend has raised public temporary wetland complexes may prevent water- awareness of the animals and promoted their conser- fowl or shorebirds from feeding at the pools, thereby vation, resulting in increased public knowledge of preventing genetic flow between occupied habitats. basic temporary wetland ecology, and working to Furthermore, small pool complexes surrounded by preserve these habitats in their regions. development will not be buffered against the runoff from developed areas and concomitant changes in the See also: Cladocera; Egg Banks; Role of in watershed hydrology. Additional threats to the temporary wetland inver- Aquatic Ecosystems. tebrate community structure include off-road vehicle use of temporary wetland habitat, conversion of temporary wetlands into permanent livestock water- holes that do not dry, and draining of temporary Further Reading wetlands. The monobasic genus Rhinobranchipus has only been collected from a single pool in the Belk D (1991) Anostracan mating behavior: a case of scramble- competition polygyny. In: Bauer RT and Martin JW (eds.) Thomas Baines Nature Reserve, Republic of South Crustacean Sexual Biology, pp. 111–125. New York: Columbia . This pool was altered by the Reserve from a University Press. temporary pool into a permanent pool, stocked with Belk D (1996) Was sind ‘Urzeitkrebse’? Stapfia 42: 15–19. fish, and had a bird observatory built next to it. Brabrand A, Richter S, Hiesel R, and Sholtz G (2002) Phylogenetic relationships within the Phyllopoda (Crustacea, Branchiopoda) based on mitochondrial and nuclear markers. Molecular Phylo- Economic Importance genetics and Evolution 25: 229–244. Brendonk L and Belk D (1997) On potentials and relevance of the

Large branchiopods are important to the commercial use of copulatory structures in anostracan taxonomy. Hydrobio-

logia 359: 83–92. aquaculture industry. The Anostracan genus Artemia is used as a rapidly growing food source for farm Browne RA, Sorgeloos P, and Trotman CNA (1991) Artemia Biology, 374pp. Boston: CRC Press. fish, mollusks, and shrimp. The eggs are collected in DeWaard JR, Sacherova V, Cristescu MEA, Remigio EA, Crease TJ, bulk from salt lakes and shipped dry to aquaculture and Hebert PDN (2006) Probing the relationships of the bran- farms. The eggs can be stored dry until needed and chiopod crustaceans. Molecular Phylogenetics and Evolution 39: then easily hatched in bulk as live food. Because 491–502. Artemia does not differentiate the particles it ingests, Eriksen CH and Belk D (1999) The Fairy Shrimps of ’s Pools, Puddles, and Playas, 196pp. Eureka, CA, USA: Mad River antibiotics, medications, or vitamins are suspended in Press. droplets of fat and fed to the shrimp. The shrimp, Linder F (1941) Contributions to the morphology and the taxo- then, become ‘living pills’ are easily fed to the aqua- nomy of the Branchiopoda Anostraca. Zoologiska Bidrag fra˚n

Uppsala 20: 101–303. cultural livestock. This form of medicating the fish is advantageous, as previously these materials dumped Martin JW (1992) Branchiopoda. In: Harrison FW (ed.) Micro- scopic of Invertebrates, Vol. 9, Crustacea, Chapter 3, into the tanks were removed by filtration, with little pp. 25–224. New York: Wiley-Liss, Inc. chance of the fish obtaining an accurate dosage, and Murugan G, Maeda-Martı´nez AM, Obrego´ n-Barboza H, and then often discharged into the local environment. Herna´ndez-Saavedra NY (2002) Molecular characterization of In addition to Artemia as an aquaculture feed, Dendro- the tadpole shrimp Triops (Branchiopoda: Notostraca) from the cephalus brasiliensis and Eulimnadia colombiensis are Baja California Peninsula, Me´xico: new insights on species diver- sity and phylogeny of the genus. Hydrobiologia 486: 101–113. used in Brazil, and Parartemia is being investigated for Rogers DC (2002) The amplexial morphology of selected Anos- use in Australia. traca. Hydrobiologia 486: 1–18. In the pet industry, Artemia is used worldwide as an Sorgeloos P, Bengston DA, and Jaspars E (1987) Artemia Research aquarium fish food, both live and dried, and the clam and its Applications 3 vols. Wettern, Belgium: Universa Press.

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Spears T and Abele L (2000) Branchiopod Monophyly and inter- Weekers PHH, Murugan G, Vanfleteren JR, Belk D, and Dumont

ordinal phylogeny inferred from 18S ribosomal DNA. Journal of HJ (2002) Phylogenetic analysis of anostracans (Branchiopoda:

Crustacean Biology 20: 1–24. Anostraca) inferred from nuclear 18S ribosomal DNA (18s

Stenderup JT, Olesen J, and Glenner H (in press). Molecular phy- rDNA) sequences. Molecular Phylogenetics and Evolution 25: logeny of the Branchiopoda (Crustacea) – multiple approaches 535–544. suggest a ‘diplostracan’ ancestry of the Notostraca. Molecular Phylogenetics and Evolution.

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