[O-02] Why do organisms create biominerals? ~Advancement of science by blending of Art-thinking~

[O02-P01] Diverse shell morphologies produced by foraminifera - a microscopic building site-

*Yukiko Nagai¹, Takashi Toyofuku^1,2 (1.JAMSTEC, 2.TUMSAT)

Keywords:Foraminifera, morphology, biomineralization, artistic

Foraminifera are unicellular organisms that live mainly in the oceans and are protists that have existed on Earth from Precambrian times to the present. The taxon is estimated to have around 4 000 species in the present, and 50 000-100 000 fossil species combined. Species are classified according to morphology, such as shell arrangement, structure and ornamentation. This means that the taxon has a relatively high morphological diversity, with more than 50 000 morphospecies recognised. They range in size from a few micrometres to the size of the palm of the hand, but as most appear to the naked eye as grains of sand, it is generally not well known that there are taxa with such a high morphological diversity. Despite foraminifera being unicellular organisms, their shell structure is complex. This is because foraminifera grow through a series of small units called chambers. In Japan, one type of large foraminifera, the star sand, is widely known to the general public. The shell of this star sand also has a characteristic morphology consisting of a complex shell chamber and multiple spines. Other foraminifera include benthic foraminifera that live on reefs and in the deep sea, and planktonic foraminifera that live in the surface layer of the ocean. In particular, by making full use of time-lapse photography using optical microscopy and ultrastructural observation using electron microscopy, the mechanisms of shell formation in foraminifera are gradually being revealed at this microscopic construction site. This presentation will introduce the mechanisms of shell formation in foraminifera and discuss some of the methodological innovations used to observe the various shells that form.