page_title: Dendrobranchiata
section_title: Life cycle
hierarchical_section_title: Dendrobranchiata / Life cycle
context_page_description: Dendrobranchiata is a suborder of decapods, commonly known as prawns. There are 540 extant species in seven families, and a fossil record extending back to the Devonian. They differ from related animals, such as Caridea and Stenopodidea, by the branching form of the gills and by the fact that they do not brood their eggs, but release them directly into the water. They may reach a length of over 330 millimetres and a mass of 450 grams, and are widely fished and farmed for human consumption.
context_section_description: Prawns may be divided into two groups: those with an open thelycum (female genitalia) and those with a closed thelycum. In the open–thelycum species, mating takes place towards the end of the moulting cycle, and usually at sunset. In closed–thelycum species, mating takes place shortly after moulting, when the exoskeleton is still soft, and usually occurs in the night. Courtship and mating may take up to 3 hours in Penaeus monodon, while in Farfantepenaeus paulensis, mating lasts just 4–5 seconds. Spawning may occur several times during the moulting cycle, and usually occurs at night.
  With the exception of Luciferidae, the eggs of prawns are shed directly into the water, rather than being brooded. The eggs hatch into nauplius larvae, which are followed by zoea larvae (initially protozoea, and later mysis) and then a postlarva, before reaching adulthood. The changes between moults are gradual, and so the development is anamorphic rather than metamorphic.
  Uniquely among the Decapoda, the nauplii of Dendrobranchiata are free-swimming. There are five to eight naupliar stages. The earlier stages have three pairs of appendages which are used for locomotion – two pairs of antennae and the mandibles. Later stages also have rudiments of other mouthparts, but the nauplius is unable to feed, and only lasts 24 to 68 hours. The body ends at a two-lobed telson, and the beginnings of a carapace emerge at this stage.
  There are typically 5 or 6 zoea stages in Dendrobranchiata, divided into protozoea and mysis. In the protozoea larvae, the antennae are still used for locomotion, but the mandibles become specialised for mastication. All the thoracic somites (body segments) have formed, and a carapace is present, covering part of the thorax. It is smooth in the family Penaeidae, but bears many spines in the family Solenoceridae. The pleon (abdomen) is unsegmented in the first protozoea, and ends in a bilobed telson, which may be used for cleaning other appendages, or for steering. By the second protozoea, segmentation appears on the pleon, and by the third protozoea, which may also be called the metazoea, the uropods have appeared.
  By the mysis stages, the pereiopods (thoracic appendages) start to be used instead of the antennae for locomotion. The larva swims backwards, with its tail upwards, spinning slowly as it goes. The carapace covers most of the segments of the thorax, and claws appear on the first three pereiopods. By the last mysis stage, the beginnings of pleopods have appeared on the first five segments of the abdomen.
  The post-larva or juvenile stage is characterised by the use of the pleopods for locomotion. The claws become functional, but the gills are still rudimentary. The telson is narrower and only retains traces of its two-lobed development. Through a series of gradual changes over following moults, the animal takes on its adult form.
caption: A juvenile Litopenaeus vannamei (whiteleg prawn)
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