Artemia : A Model Specimen for Educational Microscopy Projects in Biological and Ecological Fields

Jörg Piper

Laboratory for Applied Microscopy Research , Marienburgstr. 23 , D-56859 Bullay , Germany

Abstract: Artemia sp. (brine shrimp) can be used for pedagogic purposes as an instructive model organism to demonstrate the development and maturation of small marine crustaceans within a time window suited to classroom experiments. This article describes some characteristics of Artemia and gives several hints for culturing, light microscopy observations, and photomicrography. The morphological variations and successive differentiation associated with the maturation process are presented through various types of light microscopy images. Increasing differentiations of movement patterns are considered. Moreover, some suggestions of further experiments are reported, which can be used as introductions to fundamental principles of scientifi c work.

Keywords: Artemia , brine shrimp , light microscopy , animal growth and development , photomicrography

Introduction Artemia (brine shrimp, “sea monkeys”) is a generic group of small marine crustaceans including several species of similar size and morphology [ 1 ]. Artemia salina is the most popular species of this sort, fi rst found on the coast of England and described by Carl Linnaeus in his Systema Naturae in 1758 [website a]. In the USA, two species are ubiquitous: Artemia franciscan a [website b] and Artemia gracilis (so-called “New England brine shrimp”) [ 1 ]. T ese organisms are industrially cultivated and exported all over the world; they are used for feeding fi sh and shrimp in aquaculture farms and are distributed in pet shops and toy shops. In the latter case, Artemia is provided as a study object in experiment sets for children. Figure 1 is typical of such science-based toys. T is article provides instructions for culturing Artemia , followed by an overview of the various phases of development that can be observed in Artemia franciscana as obtained from a commercial experiment “toy” set. As Artemia is sized from 0.5 mm up to 15 mm, it is well suited for both macroscopic and microscopic observation, and successive growth processes and morphological diff erentiation can be demonstrated easily to young students. Finally, some experiments are suggested that can be used to introduce young people to elementary environmental and ecological research and to the principles of statistics and scientifi c workfl ows.

Material and methods

Commercial experiment sets, such as the “brine shrimp farm” distributed by the “Franckh-Kosmos” Company in Germany and “Thames & Kosmos, LLC” in the USA ( Figure 1 ), are readily available worldwide. In the work presented here, the “Komos” set containing Artemia franciscana was used for daily observations of living Artemia over a period of 35 days, from the first day of hatching up to the day of the last surviving animal’s death. Larvae and adult individuals were observed and photographed in bright-field and


dark-field light microscopy, and written notes were taken describing daily observations of the Artemia development. All photomicrographs and written notes were taken by an eleven-year-old boy as part of a middle school class, thus showing that commercial sets for breeding and examining Artemia can be managed well even by rather young children who are interested in exploring nature. Breeding Artemia . Commercial sets for “young explorers and scientists” contain all the equipment needed for a start-up culture: a small aquarium holding about 250 ml, an appropriate portion of sea salt, dried algae for feeding, a little bit of sand or small stones, and a supply of Artemia cysts. Of course, one could purchase these components from pet shops instead of using a starter set sold as a toy.

The aquarium should be illuminated with a 60-watt incandescent bulb (about 800 lumens) or an equivalent LED (9–12 watt, 800 lumens, 2700 K). The water temperature should be near 25 °C (77 °F), while the pH-value can range from 6.5–8.0 [ 2 ]. About 30 g sea salt (or common salt) should be added to one liter of fresh water so that the resulting density is about 1.022 g/cm 3 . The bottom of the aquarium should be covered with a thin layer of sand or small stones. When Artemia cysts are put into the salt water, young larvae (nauplii) will hatch out within 1–2 days and are immediately visible with the naked eye as small motile “dots.” For the first 3 days the nauplii can live off their yolk sac. After this period dried algae ( Spirulina powder, for instance) should be given at 2-day intervals, and small portions of baker´s yeast can be added once per week. Artemia is sensitive to poor water quality, so water exchanges are necessary if the water becomes cloudy. Reproduction and maturation of Artemia . Artemia propagates by parthenogenesis or sexual reproduction. In both cases, embryos remain within the adult female brood

Figure 1 : Typical outfi ts of commercial Artemia sets are available as experi- mental toys for young students. German slogans are translated into English.

doi: 10.1017/S1551929518000652 • 2018 July

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