Artemia Salina - Sea Monkeys Credit: Artemia Reference Center Ghent University
Great Salt Lake in Utah / USA One source for Artemia eggs Credit: U.S. Geological Survey
You probably know these amazing animals from a comic book addon.
Artemia live on Earth for 100 million years, so they are
contemporaries of the dinosaurs! Only Triops cancriformis are older, which have
not changed since more than 220 millions years.
The Artemia Salina belong to a genus of very primordial
crustacean (crawfish - crayfish) - the Anostraca (Fairy
Shrimps). Crawfish of this genus just have a divided
exoskeleton made of Chitin enhanced protein, no usual crust
of chitin (escutcheon) as other crawfish have.
A noteworthy detail is that they have 3(!) eyes - two compound eyes
and one naupliar eye. Only the compound eyes contain photoreceptors
that are light sensitive, as the naupliar eye is a primitive development.
As a young nauplius it has just one eye, the compound eyes are growing
as it gets bigger. The naupliar eye remains, but has no function anymore.
Another oddity is that the male has two(!) reproduction organs.
There are many species within the genus of Anostraca, but the
Artemia salina are very nice to grow, since the rate of
successful hatches is very high.
Artemia Salina Nauplius hatches out of it's egg Credit: Artemia Reference Center Ghent University
Artemia Salina Nauplius Credit: Artemia Reference Center Ghent University
You can buy the eggs (also called cysts) at most
aquarium shops. The cysts are produced by the fairy shrimps
when their lake is drying out (strictly speaking when the
salt level in the water is rising) or in Autumn. These eggs
contain a "sleeping" embryo at a moisture level of about 6%
to max. 10%. At these conditions there is no measureable
metabolism, which makes them very durable (several years;
survive up to 50 years (tested), but scientists believe up to
1000 years are possible).
The cysts absorb water and if the sun is shining (a signal
for growing algae and other plankton) they hatch after 24-48
hours, depending on their environment. Fresh hatched artemia
salina are called nauplii (singular: napulius) and have a
size of just 0.25mm (0.01inch). They molt like any other
crawfish when they grow - to adult they molt about 17
times.
Artemia Salina Nauplius Hatching Credit: Artemia Reference Center Ghent University
Artemia Salina Nauplius Hatched + Nauplius Credit: Artemia Reference Center Ghent University
For the first few hours, the nauplius stays within a hatching
membrane that hangs beneath the cyst shell. This is also called the
"umbrella stage" in which the development of the nauplius is completed.
Artemia Salina with egg sac Credit: Artemia Reference Center Ghent University
Male Artemia Salina Grasp Antennae Credit: Artemia Reference Center Ghent University
On the left picture a female artemia is shown.
The right picture shows the head of a male artemia.
Recognize the differences on the head.
The female already has developed an egg-sac ("blue"
ball near the tail in the left photo).
Artemia Salina reproduction Credit: Artemia Reference Center Ghent University
Brine shrimp can reproduce the usual way (male and female) and in the form
of parthenogenesis. The usual method happens when both male and female populations are abundant.
Pre-copulation starts with grasping of the female by the
large muscular graspers of the male brine shrimp. The two
artemia can swim about in this pair position for long periods
of time, sometimes up to 2 or three days.
The copulation occurs as
a very fast reflex. After
fertilization, the eggs either develop into free swimming
nauplius larvae (termed ovoviviparous reproduction - life-birth), which
are released by the mother or they are surrounded by a shell
that forms a cyst (when the environment is changing, i.e. the lake is drying out).
These cysts, while in the state of
diapause (a state of suspended development ended by certain
environmental conditions) are then deposited into the
surrounding water. Reproduction by parthenogenesis (females
only) takes place, when there are no or very few
males around. Since the female parthenogenesis results only
in female nauplii, the eventual result is an all female brine
shrimp population in that area.
Females can have about 300 offsprings every 4 days!
If the breeding temperature is about 26-28 degrees C (80-82
degrees F), a nauplius hatches within 24-48 hours, gets
pubescent in 8-14 days and lives - depending on the
concentration of salt - up to 4-5 weeks. The more
salt, the less the life expectancy.
Life Cycle of the Artemia Salina - cysts, nauplii, sub-adult, adult, life-birth or cysts...
Credit: U.S. Geological Survey
As the name suggests, Artemia salina must be grown in salt
water - some people say you can use regular salt, but the
iodine and the chemical add-on to make the salt trickle are
bad for the fairy shrimp. Better use plain sea salt (solar salt) without
any add ons or special Artemia Salt sold in aquarium stores. Artemia Salt has the
advantage that special minerals and algae are in it, which are needed by the
fresh hatched Nauplii. So if you have the chance to get such Artemia Salt, go for it!
If you'd like to use tap water, make sure you let it rest for 48 hours to make sure that the chlorine evaporates.
Some folks use water purifier (as the one sold in the Sea Monkey kits), but it is not necessary
unless you have really bad tap water. Better use bottled water (Evian etc.) - the regular one, not the carbonated.
Use about 30 gramms of salt every liter of
water. You can try more salt, but one for sure: a too high concentration of salt at the beginning reduces
the hatch rate. Take care of a rather constant water
temperature - 26-28 degrees C (80-82F) is the best, but 18-28C (64-82F) are OK. The lower the
temperature, the longer they need to hatch.
Furthermore you don't need to
illuminate your aquarium constantly - but you may need to put
it into sunlight for a short period of time (a few hours) to
start hatching, but then a light place without direct sunlight is sufficient.
Feeding is very important! But you don't have to feed for the first 3 days, since the nauplius
has still some yolk attached. Then use liquid algae (micro algae) until day 10. Then you can feed
with regular algae powder since the Artemia can now also eat bigger particles.
The water gets a very light-green/dimmish color
after putting tiny amounts of Liquicell/algae powder into it.
Do not
feed too much! About once a week is absolutely sufficient. Add some Liquicell/algae powder again only when the water is
very clear again! If the water gets dull, you feed too much! Stop feeding and replace some water!
If the number of Artemia is not too big you won't need to replace the water as
long as it remains clear. But replace some water (i.e. 20% of the tank) every 2 weeks or so to keep
ammonia, ammonium, nitrite and nitrate levels low, so that bacteria have no chance to "explode" and
do harm to the Artemia.
The sea salt
has another big advantage. There are microorganisms in it which
add to the algae powder and provide a natural environment to
the shrimp.
In a nutshell
Salt water: about 30 gramms of marine/solar salt every liter of water
Temperature: 26-28 degrees C (80-82F); 25-30C (77-86F) are OK
Light: Place your aquarium near a window with sunlight before hatching
Aeration: Carefully picking up some water with a spoon and let it drop back a few times
once a day will do, but a small (manual/electrical) aquarium pump with a little air-stone is better
Helpful Hint: Brine shrimp egg is sometimes very bouyant. Swirl the water to knock down eggs.
Some other facts:
Artemia don't sleep. They need to be in motion to breathe and eat.
Number of eyes: one eye as Nauplius, 3 eyes as adult
If there seem to be too many nauplii in your tank, don't worry. Due natural selection only the strongest will survive.
Up to 200 eggs in the egg sac of the female.
Already after 3 weeks our tiny little friends can reproduce
