Editing Daphnia (section)

==Life cycle==
Most ''Daphnia'' species have a [[biological life cycle|lifecycle]] based on "cyclical parthenogenesis", alternating between [[parthenogenesis|parthenogenetic]] (asexual) and [[sexual reproduction]].<ref name="Ebert"/> For most of the growth season, females reproduce asexually. They produce a brood of diploid [[egg (biology)|eggs]] every time they [[ecdysis|molt]]; these broods can contain as few as one or two eggs in smaller species, such as ''[[Daphnia cucullata|D.&nbsp;cucullata]]'', but can be over 100 in larger species, such as ''[[Daphnia magna|D.&nbsp;magna]]''. Under typical conditions, these eggs hatch after a day, and remain in the female's brood pouch for around three days (at 20&nbsp;°C). They are then released into the water, and pass through a further four to six  [[instar]]s over 5–10 days (longer in poor conditions) before reaching an age where they are able to reproduce.<ref name="Ebert"/> The asexually produced offspring are typically female.

[[File:DaphniaMagna LifeCycle DVizoso.svg|thumb|upright=1.75|right| {{center|Cyclic parthenogenesis in the cladoceran ''[[Daphnia magna]]''}}]]

{|
|+
|-
| {{multiple image
 | align = left
 | direction = vertical
 | width     = 180
 | image1    = Daphnia magna-female adult.jpg
 | alt1      = 
 | caption1  = {{center|Female ''Daphnia'' with eggs}}
 | image2    = Daphnid GLERL 1.jpg
 | alt2      = 
 | caption2  = Resting egg pouch (''ephippium'') and the juvenile daphnid that just has hatched from it
}}
! [[File:Rodząca dafnia.jpg|thumb|264px| {{center|''Daphnia'' giving birth}}]]
|}

{{clear}}

Towards the end of the growing season, however, the mode of reproduction changes, and the females produce tough "resting eggs" or "winter eggs".<ref name="Ebert"/> When environmental conditions deteriorate (e.g. crowding), some of the asexually produced offspring develop into males.<ref name="Ebert"/> The females start producing haploid sexual eggs, which the males [[fertilisation|fertilise]]. In species without males, resting eggs are also produced asexually and are diploid. In either case, the resting eggs are protected by a hardened coat (consisting of two [[chitin]]ous plates) called the ''ephippium'', and are cast off at the female's next molt. The ephippia can withstand periods of extreme cold, drought, or poor food availability, and hatch – when conditions improve – into females (They are close to being classed as extremophiles) .<ref name="Ebert"/> 

{{clear}}