Organism · Foraminifera
Orbulina universa
Fossil record age bounds · ≈ 85.7–0 Ma
Inferred life reconstruction
Orbulina universa
Overview
Orbulina universa is a tiny single-celled organism that floats in the sea. Its mature shell looks like a perforated ball. Inside that ball are smaller chambers made earlier in its life.[5][2]
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Key facts
The young shell consists of a succession of chambers. As it grows, it forms a large spherical chamber that encloses the earlier ones. Even as its outward appearance changes, traces of growth persist inside the tiny body.[5][2]
Time and place
Its record extends from around 15 million years ago in the Middle Miocene to the present. Today it is widely distributed from near-equatorial to subpolar seas. Among extinct animals, here is an organism that still lives in the ocean.[5][3]
The time range describes source context, not the complete duration of this species.
Size, form and skeleton
The final, outermost chamber is spherical. Small openings of different sizes perforate its surface. Imagining the small early chambers inside alongside the large outer chamber begins to reveal its distinctive growth pattern.[5]
A 2004 study describes the final spherical chamber formed at maturity as about 400–1000 µm in diameter. This single round chamber encloses the spiral chambers made earlier in life.[6]
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Habitat and reproduction
It is a planktonic foraminifer, living suspended in the water. It is commonly studied in temperate seas today. Its small shell and broad oceanic distribution together provide evidence for comparing ancient oceans.[5]
Fossil discovery
Living specimens and fossils from marine sediments have been studied together. A 1989 taxonomic guide described how the mature spherical chamber encloses the earlier chambers. Recent taxonomic research continues to compare this growth pattern and the surface structure.[2][1][5]
References
- Symphonia & Senthil2019 — Taxonomy of living foraminifera from the Bay of Bengal
- GNS Science1989 — A guide to foraminiferal classification
- Mikrotax — Temporal distribution of Orbulina
- Symphonia & Senthil2019 — Taxonomy of living foraminifera from the Bay of Bengal
- Mikrotax — Orbulina universa
- Study of daily Mg/Ca variations recorded in the shell of Orbulina universa
Research questions
Why do some foraminiferal species form a spherical chamber at the end of growth? Comparison with forms such as Globigerina, whose spiral chambers remain exposed, reveals different growth patterns. A complex growth process lies behind the simple exterior.[5][2]
Observation
Examine the larger and smaller openings on the spherical surface. Remembering that small early chambers remain inside makes it interesting to consider both the exterior and interior.[5]
Related organisms
Globigerina bulloidesForaminiferaFossil record age bounds · ≈ 85.7–0 MaDifferent ways shells grow
Orbulina ultimately encloses its early chambers in a spherical chamber. In Globigerina, the rounded chambers arranged in a spiral remain visible externally. Compare these different ways of building a body among foraminifers that float in the sea.