When you don’t Believe, A Fairy Shrimp Dies
Last night I was talking to friends about July 4ths of the past, and of course we fell upon the subject of the Stone Mountain Lazer Show Spectacular. And I said “what do you think the fairy shrimp think of the show?” They didn’t understand and I told them about the magic shrimp that appear in pools in the rock on the top of the mountain when it rains. They were in disbelief. So I have collected all the information I could find on subject.
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From: ( WEBSITE )
Vernal pools play an important role in life at the top of the seemingly barren mountain. Just as in a desert, life at the top of Stone Mountains depends on the water available in the vernal pools. When the summer is wet the pools, ranging in size from several inches to several feet, may hold water most of the year. During drought years the pools can be dry from June until October. While larger mammals like squirrel and fox rely on the water for drinking other flora and fauna depend on the water for life. Two types of shrimp frequently inhabit these pools, fairy shrimp and clam shrimp, as well as a unique variety of red moss.
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From: ( WEBSITE )
Fairy shrimp are easily identified in vernal pools. They appear as 1/2 to 1 1/2 inch crustaceans swimming upside down (ventral side up). The adult fairy shrimp have stalked compound eyes, two sets of antennae, and 11 pairs of leaf-like swimming legs. Coloration is usually red-orange due to the hemoglobin in the shrimp, but can range from translucent whitish to gray, blue or green. Because coloration is determined by the contents of the food supply in the pool which the shrimp inhabit, it is usually constant among the individuals of the pool.
Male shrimp possess an enlarged second antenna used to clasp the female during mating. Female fairy shrimp often have a brood sack on their abdomen. Female fairy shrimp usually outnumber males. They are capable of three states of mobility. Resting at the bottom of the pools, darting rapidly and drifting slowly. The shrimp propel themselves with a wave-like anterior-posterior beating motion of their legs. This action is complemented by the propeller motion of the outermost part of the legs (the “exopodites”. By changing the angle of these exopodites the speed of motion can be changed.
Fairy shrimp reproduction is initiated when the male clasps the female with its second, clasping antennae. Though the male and females swim clasped together for several days, the process of copulation takes minutes. Hours after copulation the male fairy shrimp dies. The female carries both fertilized and parthenogenetic eggs externally in its brood sack for several days before being released to fall to the bottom of the pool, or the eggs may remain attached until the female dies. The number of eggs a female produces in a clutch varies from 10 to 150. Several clutches can often be produced during the life of a female.
Females can produce two types of eggs, thin shelled “summer” eggs and thick shelled “winter” eggs. The type of egg produced is determined by the number of males in the community; summer eggs will be produced if there is a shortage of males in the population. Summer eggs hatch rapidly; the young form while still inside the brood sac. The young from these eggs will populate the pool during the same season they are laid. The winter eggs remain in the mud at the base of the pool and dry out with the pool. The eggs will hatch in the spring when the pools refills. Though the resting period usually varies between 6 to 10 months, eggs have been hatched in a laboratory after 15 years. Eggs have been subjected to temperatures of as high as 99C and as low as -190 C and remained viable. Winter eggs usually hatch 30 hours after being exposed to water.
Typically, one generation inhabits each wet period of the pool. Fairy shrimp usually hatch as nauplius. The young will develop in a series of instars. Each instar involves molting the exoskeleton to grow more segments until they reach the 20 segments of adults. Development is often rapid in the spring, but can be slowed by unusually low temperatures. The speed of development usually reflects the amount of time water will remain in the pool, or the arrival of predators in the pool. Young which have hatched from winter eggs develop more slowly than those that have hatched from summer eggs. Fairy shrimp can complete their life cycle in 16 days. This allows for rapid reproduction.
Winter eggs can be carried from pools to pool by traveling animals, or, in the case of pools that dry out completely, picked up in the wind and be blown to other pools. For reasons currently unknown to scientists, there is an uneven level of population in a pool from year to year. In a single pool, fairy shrimp may be abundant for several consecutive years and absent the next.
The leg movements serve the purpose of collecting algae, bacteria, protozoa, rotifers and floating detritus from the water. Food is then filtered from the water and scraped by sets of appendages to be eaten using a mandible mouth. Fairy shrimp have been observed gnawing on larger matter such as dead tadpoles, mollusks and amphibian eggs. The leg movements of the fairy shrimp also serve the purpose of taking the oxygen the animal needs from the water.
The ephemeral nature of the fairy shrimp reduces the limiting factors on their population. Fairy shrimp have few natural predators. They are unlikely to be heavily preyed upon by other vernal pool inhabitants because they utilize the pool before the majority of carnivorous insects have colonized the pool. Also, the wood frogs and mole salamanders breeding in the pools have not regained their regular appetite after winter hibernation and, thus, are not major predators. However, these amphibians, caddis fly larvae, dytiscid larvae, other insects, and, especially, waterfowl who utilize the pool, often do prey upon fairy shrimp. Because fairy shrimp live in temporary wetlands there are no predatory fish. The abundance of food is less of a factor in the population of fairy shrimp than in other organisms. The need of one part per million dissolved oxygen is the limiting factor in the size of fairy shrimp populations.
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BUT WAIT….. There are many kinds of fairy shrimp, and some believe that those that inhabit the top of Stone Mountain may be a special species that only live there in the granite pools. And are also worried that they may be affected by all the sweaty tourist hiking up the back side of the mountain.
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From: ( WEBSITE )
STONE MOUNTAIN FAIRY SHRIMP NOT WARRANTED FOR LISTING
U.S. FISH AND WILDLIFE SERVICE CONCLUDES
A petition to add the Stone Mountain fairy shrimp to the Federal list of threatened and endangered species is not warranted, the U.S. Fish and Wildlife Service announced today. The Service’s Southeast Regional Director, Sam Hamilton, said that the decision reflects a 12-month study that documented changes to habitat from recreational and construction activities, but could not determine that these modifications pose a threat to the shrimp.
The fairy shrimp, a relative of the freshwater crayfish, has been found in the past on the summit of Stone Mountain, a large granite outcrop in the state park in DeKalb County near Atlanta. The last documented collection of fairy shrimp was in 1951. Extensive surveys were conducted in 1997 and failed to locate the species on Stone Mountain, which may mean it is extinct.
The fairy shrimp survives dry periods on Stone Mountain as a dormant, encapsulated embryo in temporary pools found in shallow rock depressions that periodically fill with rainwater. The pools also support other plants and animals, including two plants listed by the Federal and Georgia State governments, the black-spored quillwort and the little amphianthus.
The Stone Mountain Memorial Association, manager of the parkland that contains the shrimp’s vernal pool, has already fenced off a portion of the habitat to reduce human disturbance to the shrimp and other sensitive species that occupy the vernal pool habitat. The Friends of Georgia, the group that initially petitioned the Service to list the species, will complete a conservation agreement with the Association this year, which will emphasize continued surveying, public education and additional protection.
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FAIRY SHRIMP ARE REAL! CLAP YOURS HANDS SO THEY WILL COME BACK TO LIFE!
Here is the Magical Fairy Shrimp in action: