Mammoth Winter Fairy Shrimp

Mammoth Winter Fairy Shrimps is one of the Branchinecta family. They grow up to 30 mm and live for about 12 weeks. Male fairy shrimp is longer and fatter than female shrimp, and have large branch shaped antennas near the mouth, and uses those to grasp female shrimp less than 2 seconds in mating. Female shrimp has larger brood sack than other species when compare the ratio of the size of female shrimp and brood sack; it contains about 100 eggs. The color is white with brown or black body with the other colors as shown in the pictures above, and also there is blue and red colored by the environment.

They hatch out and reproduce only during the winter season in the desert. Canadian winter storms bring down cold rain and snow to the desert, fill up dry pools with cold water. Then about 500 micrometer long shrimps hatch out, and grow up very slowly until the ice melt down and the weather becomes warmer. Then the baby shrimps grow up faster and start to reproduce in 2 weeks, but if the cold weather continues, then reproducing will be delayed for about 3 weeks. Very few of the new eggs hatch out when the weather becomes cold, and adult fairy shrimps survive in cold water even when the surface of water is frozen, and live together with the baby shrimps. Some of them hatch out during the deep monsoon season in the summer, but usually the water temperature goes up too high before they start reproducing.

The eggs are developed as a pair of lines inside female shrimp's body to tail, and move into brood sack when it is still very small and white, and don't become bigger until fertilized. After mating, the eggs get bigger and the color will be changed to brown before being released. Female shrimps produce eggs every day of the first 3 days of reproducing, then once after 3 days and even slower day by day. Eggs are 160-190 micrometer in diameter.

Usually the eggs need to be dried once to hatch like other fairy shrimps, but they have lower hatching rate of less than 50%. The eggs start to hatch out between 20 to 48 hours after submerged and keep coming out for 10 days. Shrimps can survive in wide range of temperature 40F to 72F degrees. The best water temperature of growth is between 60F to 68F degrees, but will stop growing at 10mm long. They grow larger if there is a big temperature change between the morning and the afternoon, up to 30mm.

Male fairy shrimp's ventral side.	Female fairy shrimp's ventral side.
Fairy shrimp in blue color.