anostraca

Fairy shrimp are aquatic species in the order Anostraca.

The group is thought to be monophyletic, with the Anostraca having been the first group to branch off.

As in Anostraca, there is no carapace.

It resembles modern Anostraca, to which it is probably closely related, although its relationships to other orders remain unclear.

Fairy shrimp are in the order Anostraca ("an" meaning without, "ostraca" meaning hard plate or shell).

Despite being the largest species, B. gigas has the smallest eyes of any species in the family, and possibly in all Anostraca.

Branchinecta sandiegonensis is a rare species of crustacean in the family Branchinectidae and the order Anostraca, the fairy shrimp.

It is the only species of Anostraca in Ireland, having been discovered in Rahasane turlough in 1974.

Similarly, Lepidocaris is thought to have had a similar ecology to extant members of the Anostraca, such as Artemia, inhabiting shallow, temporary pools.

Like other members of the Anostraca, T. stagnalis swims with the ventral side upwards by beating its flattened thoracic appendages, or phyllopodia.

Like all Anostraca, T. stagnalis is a filter feeder, removing microplankton, microorganisms and other organic material from suspension with its bristly phyllopodia.

He also established the current division of the Branchiopoda into the four orders Anostraca, Notostraca, Conchostraca and Cladocera.

The prey taken by B. gigas is chiefly other species of Anostraca, especially Branchinecta mackini, although it also eats copepods, cladocerans and sometimes green algae.

In his original description of the species, Scourfield noted that Lepidocaris could not be accommodated in the existing order Anostraca, and even suggested that a position outside the Branchiopoda was not unthinkable.

The trunk limbs are beaten in a metachronal rhythm, causing a flow of water along the midline of the animal, from which it derives oxygen, food and, in the case of the Anostraca and Notostraca, movement.

If the playa is wet for a month or so, the shallow waters teem with fairy shrimp, or anostraca born of eggs that lay dormant in the silt crust for long periods of time - sometimes for many years.