Morphology of the horseshoe spot (HHS) with the cavity has been investigated in details in several species of Planothidium Round et Bukht. represented by attached (sedentary) diatoms. On the base of photomicrographs obtained with light and scanning electron microscopy, the model of the HSS longitudinal section was designed and light rays tracing through it has been implemented. It has been shown that HHS is an optical system that may diffuse or focus light, depending on the refractive index of the matter inside the cavity. For the first time, HHS functions are revealed in a living diatom organism: diffusion of light over the chloroplast side turned to the substrate. Moreover, the vertical part of inner convexity generates on the attached valve the heating arc that provides a diatom cell with additional heating energy. Thus, a new mechanism of light utilization was detected in the diatom species widely distributed in benthic ecosystems. A new term, lensoid, and terminology for its morphological description are proposed.

Keywords: lensoid, light utilization, virtual modeling, light rays tracing, ecology

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1. Aas E. J. Plankton Res., 1996, 18: 2223—2249. http://dx.doi.org/10.1093/plankt/18.12.2223
2. Bukhtiyarova L.N. Algologia, 2009, 19(3), C. 321—331.
3. Bukhtiyarova L.N. Nova Hedwigia, 2006, 130: 85—96.
4. De Stefano L., Rea I., Pendina I., De Stefano M., Moretti L. Optics Express, 2007, 15(26): 18082—18088. http://dx.doi.org/10.1364/OE.15.018082
5. De Tommasi E., Rea I., Mocella V., Moretti L., De Stefano M., Rendina I. and De Stefano L. Optics Express, 2010, 18, Issue 12: 12203—12212. http://dx.doi.org/10.1364/OE.18.012203
6. Fuhrmann T., Landwehr S., El Rharbi-Kucki, Sumper M. Appl. Phys, 2004, B, 78: 257—260.
7. Kharitonov V.G., Genkal S.I. Diatomovye vodorosli ozera El'gygytgyn i ego okrestnostej (Chukotka), Magadan: MPO SVNC DVO RAN, 1912, 402 s.
8. Maidana N.I. Bol. Soc. Argent. Bot., 2000, 35(1—2), C. 49—61.
9. Meyer R.A. Appl. Optics, 1979, 18(5): 585—588. http://dx.doi.org/10.1364/AO.18.000585
10. Morales E.A. Diat. Res., 2006, 21(2): 325—342.
11. Noyes J., Sumper M., Vukusica P. J. Mater. Res., 2008, 23(12): 3229—3235. http://dx.doi.org/10.1557/JMR.2008.0381
12. Potapova M. Image of Planothidium frequentissimum 2010 http://westerndiatoms.colorado.edu/taxa/species_image/planothidium_frequentissimum/lm/1/7.
13. Round F.E., Bukhtiyarova L.N. Diat. Res., 1996, 11(2): 345—361. http://dx.doi.org/10.1080/0269249X.1996.9705389
14. Schilling R. OptoCad: tracing Gaussian TEM ₀₀ beams through an optical set-up. http://www.rzg.mpg.de/~ros/optocad.html.
15. Streett-Perrott F.A., Barker P.A. Earth Surf. Process. Landf., 2008, 33: 1436—1457. http://dx.doi.org/10.1002/esp.1712
16. Topachevskyi O.V., Oksiyuk O.P. Diatomovi vodorosti — Bacillariophyta (Diatomeae). Vyznachnyk prisnovodnykh vodorostei Ukrainskoi RSR. T. XI, Kyiv: Vyd-vo Akad. nauk Ukrainskoi RSR, I960, 412 s.
17. Treguer R., Nelson D.M., Van Bennkom A.J., De Master D.J., Leynaert A., Queguner B. Science, 1995, 268: 375—379. http://dx.doi.org/10.1126/science.268.5209.375
18. Van de Vijer B.V., Van Kerckvoorde A., Beyens L. Nova Hedwigia, 2003, 76(1—2): 225—243. http://dx.doi.org/10.1127/0029-5035/2003/0076-0225
19. Vernadskiy V.I. Zhivoe veshhestvo v khimii morya, Petrograd: Nauch. him.-tehn. izd-vo, 1923, 36 c.
20. Wojtal A.Z. Bibl. Diatomologica, Stuttgart: J. Cramer in Borntraeger Science Publishers, 2013, 59, 436 p.
21. Yamanaka S., Yano R., Usami H., Hayashida N., Ohguchi M., Takeda H., Yoshino K. J. Appl. Phys., 2008, 103(7): 074701—074705. http://dx.doi.org/10.1063/1.2903342