ARTEMIA NYOS – ‘SEA MONKEYS’
What is a ‘Sea Monkey’?
A ‘sea monkey’ is a variant of the brine shrimp Artemia salina produced at the New York Ocean Science Laboratories and thus termed Artemia nyos and is commercially marketed as 'Sea Monkeys'.
Where do ‘Sea Monkeys’ live?
Artemia salina are sold as a larval fish diet for aquaculture and the large numbers required for this trade are harvested from a number of sites, including the Great Salt Lake in Utah, USA.
The Great Salt Lake is an inland sea with a salinity of around 10%, the natural environment supporting the life cycle of the brine shrimp. Artemia are a fascinating species and highly adaptive to varied environment conditions. It has been reported that they can survive at water temperatures from 4-41C (38-106F). Artemia in the Great Salt Lake must tolerate the changing salinity levels, from 7% up to and even over 12% which are influenced by the results of high or low water year levels which occur naturally with the weather conditions.
How do ‘Sea Monkeys’ reproduce?
The brine shrimp life cycle is dependent on the very specific environmental conditions occurring in the high salt lakes. They can reach adulthood in as little as 21 days, and begin the reproduction cycle, producing eggs or cysts. Adults may survive and reproduce for several months. If the environment conditions are ideal, as stated above, the eggs will begin to hatch within 18-24 hours. When winter approaches, and the weather temperature drops the lake water temperature to 8C (45F) or below, the adults begin to produce eggs rapidly, laying in a natural reserve for the next spring hatches. Then, as the water temperature drops to freezing, the adults die off and the eggs float in the lake waiting for the warmer temperatures of spring to begin the life cycle again. Freezing temperatures do not harm the eggs which go into a diapause and can survive freezing temperatures for long periods. The same occurs during periods of drought. Eggs can survive completely dessicated for prolonged periods and this is the state in which they are sold as ‘Sea Monkeys’.
Artemia females are generally larger than males, often exceeding 1 cm (0.4 in) in length while the males only reach 0.75 cm (2.5 in). Females can be differentiated from males by the presence of a caudal egg sac, while the males have small hairs on the chin. Artemia can give birth to live young or produce eggs. The latter, termed oviparity occurs at times of dessication and a new water source causes egg swelling and release of the nauplius. Artemia may also exhibit ovoviviparity with egg development occurring within the female or necroovoviviparity where in periods of dessication the young can develop inside the dead parent's body.
When you purchase ‘Sea Monkeys’ what do you receive?
The Artemia sold commercially as ‘Sea Monkeys’ are oviparous eggs awaiting the addition of water to emerge as young nauplii. Within five minutes of reconstitution in dilute saline the eggs develop into motile nauplii. The 'Sea Monkey' kit includes a sachet to ensure that water used is at the correct salinity and metal ion- and chlorine-free, a sachet of eggs and a sachet of Artemia food, dinoflagellates or marine algae.
How should I feed the ‘Sea Monkeys’?
As noted above the 'Sea Monkey' kit includes a sachet of food, the composition of which is not made clear in the accompanying literature. Artemia to be used as food for larval fish stages in aquaculture systems are often fed on heterotrophically grown and freeze dried algae and nutrient-enriched yeast to boost the nutritional value of the Artemia.
What diseases do Artemia encounter?
There are disease causing organisms which affect Artemia, some of the most common being algal blooms. Ironically, since marine algae are a key foodsource for Artemia these organisms can, in excess, cause cytotoxic effects in the brine shrimp although with less toxic effects than in mammals similarly effected. While bacterial overgrowth is not reported in the literature as a significant problem in Artemia grown as a foodstuff or in research, the literature provided with the ‘Sea Monkeys’ kit suggests that bacterial overgrowth can cause problems through oxygen consumption leading to hypoxia for the Artemia. Overfeeding of the Artemia can lead to a bacterial population explosion and the company distributing ‘Sea Monkeys’ provides what they term a 'final cure' Sea-Medic which it is presumed is a soluble antibiotic.
A more concerning condition is the toxicity of metal ions to developing Artemia. Emerging Artemia young are much more sensitive to metal ion toxicity than are larvae or adults. Copper and lead salts are toxic at levels of 100 nM hence the concern with ‘Sea Monkeys’ about the use of water from household taps where copper pipes may give high levels of copper ions. Zinc was less toxic and nickel was least toxic.
Conclusion
‘Sea Monkeys’ are a fascinating and worthwhile pet for anyone.
Ark Veterinary Centre