The Great Salt Lake ecosystem is a difficult place to survive for most organisms, partly because of the high salinity and, second, because of widely varying water temperatures. The brine shrimp's life history and physiology allow them to survive harsh environmental conditions and be a very successful member of the GSL ecosystem.
Brine shrimp are able to control how much salt they let into their body tissues better than any other organism in the world thanks mostly to the skin lining of the stomach and the gills. The outer layer of the shrimp is impermeable to water, so the only way for salt water to enter is through the mouth during feeding. As shrimp ingest water, it is absorbed through the stomach lining. Salt is then pumped out the gills instead of going through the digestive tract, as it would in most other animals. Another structure, the neck gland, is also thought to act as a salt pump, and it is especially important in immature shrimp when other excretory organs are under-developed. Brine shrimp use these two pumps to maintain a relatively stable salt concentration within their bodies: when the surrounding water is highly salty, the pumps work harder and have a higher output. When the surrounding water is less saline, the pumps slow in order to retain some salts within the shrimp.
Along with the saline environment, brine shrimp must also deal with low oxygen levels. Humans use a protein called hemoglobin to bind oxygen in our blood. This protein transports oxygen to our muscle cells. Brine shrimp have developed three very efficient types of hemoglobin, which increase in concentration as salinity increases. Some scientists have noted a red coloration of brine shrimp that live in very salty water, and attribute this color to the presence of hemoglobin carotenoids, plant compounds derived from food sources. However, Artemia range in color from a pale green, to red, to semi-transparent grey. The cause of these color differences is unknown, as all colors have been observed at various salinity levels.
Brine shrimp trivia: The GSL is an amazingly harsh environment, but brine shrimp have evolved a series of physiological characteristics that allow it to survive. Can you name three of them? Five are listed below.
Crustaceans have two sets of antennae; in male brine shrimp, one set of antennae develops into muscular graspers and one set develops into sensory antennae. In females, the graspers are much less pronounced and non-functional.