(and the Mystery of What Sea Monkeys are)
The topic arose in the conversion with an FBSK (fellow brine shrimp keeper) regarding where we can bulk-buy cysts of Artemia salina, the types marketed for aquarium hobbyists for fish food.
As we investigated, I noticed that many brine shrimp cysts products on the market have very likely to be mislabelled as Artemia salina when they are more likely to be, in fact, Artemia franciscana.
A few examples:
Ocean Nutrition – Instant Baby Brine Shrimps
Their description clearly stated that the cysts were harvest from the Great Salt Lake of Utah. However, the current consensus is that the brine shrimp species at the GSL is A. franciscana.
This mislabelling is likely to be a vestige of the past. Since the 19th century, brine shrimps had been known at the GSL but were referred to as Artemia salina – at the time, most brine shrimps were lumped together under the same group.
In 1906, Kellogg had identified the brine shrimps at the San Francisco Bay specifically as Artemia franciscana. However, it is not until much later that the North American strains were more definitely confirmed to be of the same linage through DNA and phylogenetic analysis with the huge advance of genetic technologies in the 21st century.
Classification and naming for Artemia had always been chaotic. The historical context and situation are well-documented in this paper published in 2021, which still views the situation as problematic even today.
It would have appeared that in the early days of the brine shrimp industry taking its shape, the term Artemia salina was used to refer to brine shrimps in general, even by scientists working in the field. For example, this paper published in 1977 referred to the GSL brine shrimps as A. salina.
Brine shrimp companies operating since the mid 20th century may have been using this classification in their marketing materials without any update. Hence the confusion.
On a side note, this is one of the reasons why I have suspected that the brine shrimp species used in Sea-Monkeys is A. franciscana.
Part of the well-known Sea-Monkeys creation story is that the brine shrimps are “created” in the lab by hybridising different Artemia species. This happened in the mid-70s, at the height of the US brine shrimps business where cysts were harvested predominantly from the SF Bay salterns and then GSL.
To me, it’s very plausible that the cross was made using the different strains of brine shrimps sourced from those US habitats. With hindsight, we know now that they are all A. franciscana, so cross-breeding among them would be possible. However, they may have been considered different species back then due to all the historical naming confusions. For example, the brine shrimps at the SF Bay were already named A. franciscana, while the ones at the GSL were still referred to as A. salina.
Nowadays, A. salina is considered to occur naturally in the old world habitats only. I have come across several references that mention the introduction of A. franciscana to those old-world habitats as an invasive species but have not seen any mentioning cross-breeding between the two. I’ve made a layperson’s deduction that cross-breeding between them does not happen simply because they are cohabiting.
Considering all those, I think it is reasonable to suspect that the “hybrid” brine shrimps known as Sea-Monkeys are crosses between strains or subspecies of A. franciscana.
PS.
There is another theory I have been contemplating regarding the Sea Monkeys “hybrid”.
Entering the phenomenon of Artemia parthenogeneticais, where the male from a parthenogenetic population cannot fertilise the females of the same group but can produce offsprings with females of other sexual species.
In A. parthenogeneticais, the occurrence of males is extremely rare – around one in hundreds to thousands. This is not compatible with the observation of a typical Sea-Monkey colony where males are abundant. When I surveyed the Sea-Monkeys community group by searching with the keywords “male” or “mating”, many posts describe those in people’s Sea-Monkeys tank. So I think we can safely rule out that Sea Monkeys are a type of A. parthenogeneticais.
However, I have no idea about the sex ratio in the first generation of offsprings (F1) from crossing between a “rare male” from A. parthenogeneticais and a sexual female, and what the possible outcome would be when crossing such F1 males and females.
The article I linked above suggests that the parthenogenetic trait could “spread” to the sexual species by such crossing. However, I am not entirely sure that is necessarily the case at the moment. And I cannot think of a way to verify if this hypothesis has any leg.
So at this moment, this remains a possibility for me to do further research and acquire more understanding of the topic.
Monkeys in a Jar 