Artemia salina (Linnaeus, 1762)

Meyer, Stephanie, Araujo, Thiago Q., Walsh, Elizabeth J., Wallace, Robert L. & Hochberg, Rick, 2023, Integrative microscopy to explore physical and nanomechanical properties of eggshells of diapausing embryos in Rotifera: a proof-of-concept study, Journal of Natural History 57, pp. 1984-2005 : 1993

Phylum Arthropoda :

Artemia salina

SEM

The spherical egg (cyst) of A. salina measured ca 190 µm in diameter (̄x = 188.0 ± 8.0 μm). The smooth outer surface was devoid of any ornamentation but did show a small number of randomly distributed bumps and indentations ( Figure 3a,b ).

TEM

Not performed in this study. Measurements estimated from studies by Morris and Afzelius (1967), Mazzini (1978) and Sugumar and Munuswamy (2006) showed an average shell thickness of 7.50 ± 0.04 µm (SD).

AFM

Topography of the outer shell displayed comparable morphologies to those visualised with SEM, but with more texture observed under AFM ( Figure 3c ). Small bumps ranging in size from 0.3 to 1.1 µm were present on the surface. An example force–distance curve that displays how Young̾s modulus values were collected for a single spot on one egg is shown in Figure 3d . The average Young̾s modulus ranged from 17.40 to 22.51 MPa with a mean of 20.93 ± 1.57 MPa (SD) ( Table 1 ). Hardness values ranged from 1.90 × 10−2 GPa to 2.43 × 10−2 GPa with a mean hardness of 2.20 × 10−2 GPa ± 1.67 × 10−3 GPa (SD) ( Table 2 ).

Figures

Figure 3. Characterisation of cysts of Artemia salina. a. Scanning Electron Microscopy of cysts. b. Closeup of the surface of a cyst. c. Topographic image of the external surface of a cyst generated with Atomic Force Microscopy. d. Force–distance (FD) curve generated from a single location on a cyst. Parameters for the position of the location on the eggshell are indicated by the cursor positions (screen shot). Maximum force (MF, green circle) and 20% maximum force (20% MF, orange circle) are indicated on the FD curve Scale bars: A = 100 µm; B = 25 µm.