Sepia mestus, also known as the reaper cuttlefish or red cuttlefish, is a species of cuttlefish native to the southwestern Pacific Ocean, specifically Escape Reef off Queensland ( ) to Murrays Beach off Jervis Bay ( ). Reports of this species from China and Vietnam are now known to be misidentifications. S. mestus lives at a depth of between 0 and 22 m.
Life cycle and mating behavior
To attract a potential mate, a male will perform various displays to catch the attention of a female. Once a male is successful in attracting a mate, the male will insert the hectocotylus into the female’s mantle cavity to fertilize the female. The female will then lay her eggs nearby.
After spawning and brooding, male and female adults usually die shortly after. Like most members of the class Cephalopoda, S. mestus are gonochoric. After the embryos develop for about two months, they will hatch and remain in a planktonic stage briefly before developing into adults.
S. mestus lives in depths up to 22 m. 
S. mestus typically lives on rocky reefs and is typically seen under ledges (Norman 2003).
Increasing levels of CO2 in the atmosphere causes ocean acidification and is potentially a threat to all cuttlefish. According to studies, high CO2 concentrations, cuttlefishes tend to lay down a denser cuttlebone. This could negatively affect cuttlefish buoyancy regulation (Gutowska et al. 2010).
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- Current Classification of Recent Cephalopoda
- "Sepia mestus, reaper cuttlefish". sealifebase.ca. Retrieved 2018-02-25.
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- "Cuttlefish - Sepia mestus - Details - Encyclopedia of Life". Encyclopedia of Life. Retrieved 2018-02-25.