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The Branchiopods are a sub-group (class) of Crustaceans and contain the fairy shrimp (sea monkeys), clam shrimp, water fleas and tadpole shrimp. Most of these are small, fresh or brackish water animals that feed on plankton and detritus, with the exception of the water fleas (Cladocera), many of which are marine. There are almost 800 known species and the major groups have many differences between them.

Clam shrimps (Conchostraca)

  • have appendages along the entire thorax/abdomen whereas the appendages are found only on the anterior segments of cladocerans;
  • Their carapace is bivalved with a hinge that allows opening and closing of the two halves;
  • Their body is completely enclosed in the carapace but the head of cladocerans is not covered by their carapace;
  • They are only found in freshwater.

Clam shrimp

Water fleas (Cladocerans)

  • They are quite small with most between 0.5 mm and 3 mm;
  • Their carapace of cladocerans covers the throrax/abdomen but not the head, and is folded down the midline giving them a bivalved appearance;
  • Most species swim by making short jumps using their second pair of antennae. These are also used for catching food;
  • The small number of Cladocerans living in marine habitats are very different to the freshwater species having huge eyes andbeing active predators instead of being filter feeders like most of the freshwater species;
  • They are either herbivores, filtering plankton, or carnivores.

Cladocera (water flea) a Daphnia species
Image © shadowshador Flickr

Fairy shrimp (Anostraca)

  • tThey live in fresh or saltwater but not in oceans or seas;
  • Their size ranges from one to 10 cm;
  • They do not have a carapace;
  • They have elongate bodies with leaf-like appendages that they use to swim belly up;
  • They are mainly herbivores eating algae from the plankton although some larger species are predators;
  • Their eggs will survive drought and large temperature extremes for several years and hatch about 30 hours after rains fill the pools where they live.


Tadpole shrimp (Notostraca)

  • There are only two groups - the Triops and Lepidurus totalling nine species, considerably less than any of the other branchiopod groups;
  • They have broad, plate-like carapace that covers their head and the front part of the thorax and a long, narrow tail;
  • Their jaws (mandibles) are quite large, with many toothlike projections. They are omnivores, diging around in the mud searching for plankton and larger prey such as worms, chironomid larvae, small, dying or weak tadpoles, and even each other ;
  • Most hatch from unfertilized eggs which can withstand freezing and drought, and can hatch after 12 months as long as 25 years after they are released from the female.

Triops Longicaudatus

Sea monkeys - A popular pet
Sea-Monkeys is the brand name for Artemia sold in hatching kits, as a novelty aquarium pet aimed at children, in the United States and the United Kingdom since 1960. They are often sold in a blue or red, plastic aquarium. Inside, there are water purifier, eggs and food. It is sold under the title "The Amazing Live Sea-Monkeys Ocean-Zoo". They are a variant of brine shrimp or Artemia salina. The ability of unhatched "Sea-Monkeys" that allows them to be packaged and shipped is that they enter cryptobiosis, a suspended animation that occurs naturally in Sea-Monkeys in order to help them survive until ideal conditions appear. Sea-Monkeys can stay in this state for up to 2 years. When released into water that meets the conditions needed for the Sea-Monkeys to survive, they leave this state and emerge from their cysts.



Simocephalus sp - a freshwater water flea
Image © Jasper Nance Flickr

Curtis' sea monkey (brine shrimp)

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