Foraminifera collected from the Indian River, Florida were buried in "sterile" sand to depths of 0.5, 1.0, 2.0, 3.0, and 4.0 cm. The miliolid Quinqueloculina impressa Reuss was the first to emerge after burial. For this species the time of emergence in minutes is related to the burial depth in centimeters by the equation T = 434.3Z)'^". Effective overburden stress, foraminiferal velocity, and time of emergence are related in a model for the vertical movement of foraminifera.
SYNOPSIS. The foraminiferan Glabratella ornatissima (Cushman) undergoes plastogamy during reproduction. In this process, 2 (or rarely more) individuals join together by their apertural sides to mutually exchange gametes. The apertural sides and internal septa are dissolved, forming a single large brood chamber. After the zygotes grow to a 2‐ or 3‐chambered stage, the young foraminifera are liberated from the enclosing parent tests.
Scanning electron micrographs and histochemically stained thin sections indicate that the reproductively mature individuals are firmly united by an organic membrane during plastogamy. This membrane is monolamellar, less than 1 μ thick and has minute lumps on its surface. Biochemically it contains a nonsulfated acid mucopolysaccharide, which is unlike the membranes associated with CaCO3 deposition lining the interior of foraminiferal tests. The young foraminifera liberate themselves by secretion of an enzyme which degrades the membrane. The mechanism of plastogamy is interpreted to be an adaptation to life in turbulent waters that would decrease the chance of gamete union or zygote survival were the gametes released and fertilized freely.
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