A tubular process of some centric diatoms, usually associated with the secretion of §-chitin to maintain buoyancy in the plankton. The fultoportula consists of a central tubular process surrounded by two or more satellite pores. Externally, the fultoportula appears as either a tube or a simple pore in the valve wall. The plural form is 'fultoportulae'.
Round, F.E., Crawford, R.M. and Mann, D.G. (1990). The Diatoms. Biology and Morphology of the Genera. Cambridge University Press, Cambridge, 747 pp.
Image Credit: Sarah Spaulding
Image (also SEM) of the external view of Stephanodiscus yellowstonensis. The external expression of marginal fultoportulae is indicated by arrows; the marginal fultoportulae are positioned below spines.
Image Credit: Marina Potapova
Internal view of valve of Stephanodiscus sp. showing the rimoportula (R), central fultoportula (CF) and four marginal fultoportulae (MF). Each fultoportula has two satellite pores.