Super Salty Shrimp: Two Paths of Development
Marine lakes, an environment created by the ocean and evaporation can have various different salt compositions depending on the location. These lakes have inflows from the ocean, creating a segmented marine environment likely to produce organisms not found in the ocean. Areas with high amounts of evaporation will leave high levels of salt behind in the lake. Leading to a hyper saline environment, an environment the Brine Shrimp Atremia saline can thrive in.
Artemia saline is a halophile, this is an organism that can tolerate or grow within high saline conditions. After going through several development stages and two possible starts in life the shrimp will grow to have 20 segments and 10 appendages and live without a shell.
A Change in Reproduction
There are times in life when things are just not possible. For humans our response is to simply not carry out these tasks/duties. For the brine shrimp its not so easy, biological processes will occur no matter what which could lead to extinction. Including when the marine lake drys out, a common season process creating an extreme hyper saline environment. A place no ordinary embryo could survive. This is where one of the adaptions the Brine Shrimp is known for comes into play. A female is able to predict the future… Well they may not be that advanced but they are able to predict forthcoming environment changes, perceived by changes in conditions. From this they then change the stance of their reproduction and start producing embryos which are highly resistant to dehydration, this occurs when the conditions show a reduction in water levels and temperature. This differs to the norm as usually free swimming Nauplii are produced. The nauplii would be sure to die if the salinity is too strong. This is an incredible adaption, the shrimp is able to perceive what comes next and counter its reproduction to ensure survival.
The embryos are so dehydration resistant because they are encysted gastrula embryos otherwise known a cysts. Which act as an information harbour during times of extreme salinity. Thus keeping the species alive during times an adult or larval stage couldn’t survive. These embryos enter a stage of dormancy, development is delayed until signs of reduction in the hyper saline conditions are present, these being water level and temperature increase. When this occurs the embryos come out of dormancy and carry on with development. The main aid of the embryo is a inner cuticle which is impermeable to salt, this is the direct adaptation which protects the species in the high salt concentrations to ensure survival.
Many will have encountered the brine shrimp without visiting a marine lake. The embryos are collected and sold as “Sea Moneys”, a product directed at children. The embryos come in a dry paper packet, which shows the ability of the embryo to resist dehydration perfectly. The directions are to mix a “water purifier” and water in a small tank and a day later place the embryos in, then wait till they come out of dormancy. When they hatch a 5 day wait is recommended before feeding. The children will then over a period of time be able to see the different developmental stages of the brine shrimp. These stages being the nauplii and larval stages, these creatures are thought to be the worlds best osmoregulators. Since there is no filter or pump in this tank making it stagnant water, it is clear that the species is able to undergo osmoregulation very efficiently. In fact these stages of development are thought to be able to up to 10 times the salt concentration in the sea, thus making the environment a “Sea Monkey” would experience look like a breeze.