This is a great biology experiment for high school that shows how brine shrimp nauplii move using phototaxis (light attraction) and geotaxis (movement using Earth’s gravity for orientation).
Although this presentation was designed for high school students, it can be modified for use in middle school.
Brine shrimp, also known as Artemia salina, have become a popular model organism used in a wide variety of scientific experiments over the past few decades But why are these tiny crustaceans so commonly utilized in research? In this article, we’ll explore the many advantageous characteristics that make brine shrimp such a useful experimental tool across diverse fields
An Extreme Survivor
One of the main reasons brine shrimp are so valued in experiments is their incredible ability to adapt and survive in conditions that would kill most organisms Brine shrimp are native to salty lakes and ponds with extremely high salinity They thrive in hypersaline environments that can reach salt concentrations as high as 25% – that’s around 8 times saltier than ocean water!
This gives researchers an extremely resilient test subject to explore how different stressors and environmental toxins impact living systems Brine shrimp can withstand drastic changes in temperature, UV radiation, pH shifts and even exposure to heavy metals and pesticides Scientists can dial up the intensity of these stress factors in a controlled setting using brine shrimp as a model to understand toxicity thresholds in organisms.
Rapid Life Cycle
Another advantage of brine shrimp for experiments is their short lifecycle. Under optimal conditions, they can complete their entire lifecycle of hatching to reproducing adults in as little as 2-3 weeks. This allows researchers to study developmental effects and multigenerational impacts in a relatively short timespan.
Brine shrimp eggs can remain dormant in cyst form for years, then rapidly hatch and develop when conditions are right. This quick turnaround from cyst to swimming larvae makes it easy to synchronize large numbers of brine shrimp at the same developmental stage for experiments. Their brief life cycle also enables scientists to efficiently study inheritable mutations and evolutionary adaptations under different selection pressures across multiple generations.
Easy Maintenance
Given their resilience, brine shrimp are relatively easy and inexpensive to raise and care for over the course of experiments. Their small size allows them to be housed in high densities with simple setups. Commercial brine shrimp eggs are widely available and can be purchased in bulk. Hatching cysts and getting larvae does not require any special skills or feeding.
Adult brine shrimp feed on microalgae and yeast, which can be grown or purchased quite cheaply. These practical advantages allow many labs to maintain large populations of brine shrimp as a general research organism to have on hand for various types of experiments.
Sensitive Endpoints
The brine shrimp model allows researchers to assess multiple endpoints when testing compounds for toxicity or other biological effects. These include evaluating mortality rates, developmental abnormalities, behavioral changes like swimming or feeding patterns, growth/size measurements, and even genetic mutations.
Brine shrimp larvae in particular tend to show greater sensitivity to toxic substances compared to adults. This provides scientists with a broader range of measurable outcomes to detect even subtle influences of experimental variables. The diversity of potential test endpoints makes brine shrimp very useful for ecotoxicology studies.
Correlation to Other Species
An important consideration in choosing any animal model for research is how well it correlates to other organisms. A major reason brine shrimp have become so popular as an experimental species is their toxicity response shows good agreement with data from studies done in rodents and humans.
This suggests brine shrimp can serve as an ethical and cost-effective preliminary testing model before moving on to experiments with mammals. Their sensitivity also mirrors that of cell cultures, making brine shrimp a good intermediate step before in vivo animal studies.
High Throughput Testing
The small size of brine shrimp allows researchers to conduct high volume experiments using multi-well plates. This enables efficient toxicity screening of dozens to hundreds of compounds or experimental conditions at once. Their short life cycle also means substantial data on differential survival, growth rates, behavior and reproduction can be gathered quickly.
Automated imaging systems can track and record brine shrimp movements and development over time. This capacity for high throughput testing makes them ideal for applications like pharmacology, genetics, and environmental monitoring.
Non-Mammalian Chordate
From an evolutionary perspective, brine shrimp offer some advantages over other non-vertebrate model organisms. As crustaceans, they are more closely related to humans than single-celled yeast or bacteria models widely used in research.
Brine shrimp belong to a subphylum known as cephalochordata, which means they have a primitive spinal cord-like structure. This still sets them far apart from humans, but gives a slight leg up over some invertebrates in extrapolating toxicity data to humans.
Applications in Research
This combination of attributes has made brine shrimp an extremely versatile research organism utilized in diverse fields of study. Some examples of their experimental applications include:
- Ecotoxicology – Monitoring water pollution, assessing toxicity of heavy metals, pesticides, nanoparticles
- Pharmacology – Drug discovery and testing, anesthetic effects, medicinal uses of natural compounds
- Genetics – Mutagenesis research, screening factors that cause DNA damage
- Aquaculture – Testing feeds, nutrients and water conditions for fish, shrimp, and shellfish farming
- Education – Classroom teaching tool for development, evolution, physiology
Brine shrimp have proven an extremely useful model across these realms and more. Researchers are continually identifying new ways to harness these unique crustaceans to advance scientific understanding.
Standardized Protocols
The ubiquity of brine shrimp as an experimental organism has led to the development of standardized protocols for toxicity testing. The simplicity of raising brine shrimp and tracking mortality rates has made this a very common first-line assay when investigating new pharmacologic compounds or environmental contaminants.
By following consistent procedures, it allows for comparison and reproducibility across diverse studies and laboratories. Regulatory agencies even reference brine shrimp toxicity data when evaluating new chemical agents up for approval. Having a standardized protocol increases the utility and validity of the brine shrimp model for screening applications.
A Unique Research Niche
While no single organism can fully represent the diversity of life, brine shrimp have found an important niche as a broadly applicable research tool. Their hardiness allows for flexibility in experimental designs probing how environmental stressors influence living systems. Rapid generational turnover facilitates inquiries into development, genetics and evolution. And their sensitivity to toxins at various life stages renders them invaluable for screening compounds for drug discovery and ecotoxicology.
Brine shrimp present an optimal balance of being complex enough to extract biologically meaningful data, while simple enough to rapidly setup replicated experiments. Continued enhancements in imaging and data analysis will further expand insights extracted from the brine shrimp model. These tiny saltwater survivors will no doubt continue making a big impact across diverse realms of research.
Procedure: Hatching of Brine Shrimp Eggs
Brine shrimp eggs are available from tropical fish dealers. Purchasing in quantity (1/2 to 1 lb. ) greatly reduces the unit price.
Each egg is as small as a grain of fine sand. A teaspoonful contains many thousands of eggs. The eggs will remain viable for several years if kept cool and dry.
The eggs will hatch into tiny larvae called nauplii (singular: nauplius) if put in a 2% to 4% salt solution. Iodized salt and reagent grade salt should not be used. Sea salt, which you can usually find in the gourmet section of your grocery store, gives the best results. A 4% salt solution is easy to make by starting with a saturated solution (add about 8 ounces of salt to 2 cups of water in a quart jar, stir vigorously, and let the extra salt settle) and adding 10 ml of the saturated supernatant solution to 1 quart of water. When you use tap water, let it sit overnight to get rid of the chlorine that was used to treat it. ).
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If this is done gently, the eggs will float on the surface. Penetration of the salt solution into the eggs initiates development. Oxygen is required, and this is obtained directly from the air by the floating eggs. At room temperature, nauplii will come out about 36 hours after being wet. At 30°C, they will come out about 24 hours after being wet.
If you don’t move the boxes during this time, the eggs that haven’t hatched will stay on top, and the quickly swimming nauplii will be in the solution. These can be separated by siphoning the bulk of the solution into a beaker or other container.
Soon, the nauplii will sink to the bottom of the vessel. This is known as positive geotaxis, and you can make a concentrated suspension of them by using a dropper pipette to move them to a test tube.
Put a stopper on one end of the glass tube and move the concentrated nauplii suspension to the tube while holding it vertically. Fill it up to the top with salt solution and make sure there are no air bubbles in the top end. To do this, hold a small pin in the open end of the glass tube and put the stopper in place. The pin bends the stopper and lets extra solution and air escape when the stopper is pushed into the tube. If the pin is carefully pulled out, the stopper will stay in place and no air bubbles will be trapped in the tube.
Invert the tube a few times to spread the nauplii evenly and place it on a horizontal surface. Point the light from a penlight or small flashlight at one end of the glass tube. Place a paper towel over the rest of the tube. After some time, the lit end of the tube will have almost all of the nauplii.
If the glowing end of the tube is then turned on, the nauplii will move back to that end. Because light bounces off the glass tube, not all the nauplii move to where it’s brightest; some will stay in the tube’s body. If this experiment had been done in a test tube with a round bottom, there would be a lot of nauplii in the middle of the part of the tube that curves in a half-spherical shape. This is because the bottom acts as a crude lens, concentrating the light at its focal point. ).
A Demonstration of Photo- and Geotaxes in Nauplii of Artemia Salina
By Daniel C. Koblick
Illinois Institute of Technology 5436 S. East View Park #1 Life Sciences Building Chicago, IL 60615
3101 S. Dearborn Chicago, IL 60616
Students are presented with an easily observed orientation behavior of small crustaceans with respect to light and gravity. Following this, they are given information about the organisms’ habitat and how they eat, and they are asked to connect what they have seen to the organisms’ needs in terms of adaptation.
- 1 plastic shoe box with lid
- 1 or 2 liters of 4% NaCl
- A vial of brine shrimp (Artemia salina) eggs
- 1 siphon made up of a two-foot piece of India rubber tubing with six-inch pieces of glass tubing inserted into each end
- 2 wire pinch clamps
- 1 one-liter flask (a clean milk carton will do)
- A 100 ml graduate cylinder
- 1 glass tube, about eight inches long and of approx. one cm internal diameter .
- 2 black rubber stoppers to fit above tube (Size 00)
Brine Shrimp Lab Overview
Why are brine shrimp toxicity assays important?
This is mostly because brine shrimp assays are simple and quick, but also due to the ethical implications associated with inducing harm to vertebrate predators in toxicity assays.
What is a brine shrimp lethality test?
Nowadays, brine shrimp lethality assays are extensively used in research and applied toxicology [ 29 ]. There is a tendency to use an Artemia salina assay in toxicological tests that screen a large number of extracts for drug discovery in medicinal plants [ 30 – 33 ].
Why is solvent important in brine shrimp lethality bioassay?
In summary, solvent is a very important player in brine shrimp lethality bioassay. The maximum working concentration of solvents in brine shrimp lethality bioassay contributes significantly to the field. Development of new solvents and detergents and carefully design of experiments will also improve this assay greatly.
Is brine shrimp toxicity a viable preliminary assessment of marine natural products?
In conclusion, this study demonstrates that the brine shrimp toxicity assay can provide a viable preliminary assessment of the toxicity of marine natural products, particularly if a dose-response is observed. For verification, additional experiments such as the brine shrimp hatchability assay can be conducted.