Tag Archives: plankton

Friday Fellow: Bubble Globigerina

by Piter Kehoma Boll

A little more than a year ago I introduced the first foraminifer here, the tepid ammonia. Now it is time to bring the second one, this time a planctonic species that is rather famous and whose scientific name is Globigerina bulloides, or the bubble globigerina as I call it.


A live specimen of Globigerina bulloides. Photo extracted from Words in mOcean.

This species can be found throughout the world, but it’s more common in cold subantarctic waters and a little less common in subarctic waters. The most common areas are the North and South Atlantic and the Indian Oceans, but the tropical records are most likely a misidentification of other closely related species.

The bubble globigerina usually lives in the upper 60 m of the water column, at least while reproducing, and feeds on other planktonic organisms, especially microscopic algae. In oder to maximize the ability of their gametes to meet in the vast extension of the ocean, the bubble globigerina synchronizes its sexual cycle with the moon cycle, reproducing during the first week after the new moon. It is, therefore, a kind of biological calendar.

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Bé, A. W. H.; Tolderlund, D. S. 1972. Distribution and ecology of living planktonic Foraminifera in surface waters of the Atlantic and Indian Oceans. In: Funnell, B. M.; Riedel, R. (Eds.) The Micropaleontology of Oceans, Cambridge University Press, pp. 105–150.

Schiebel, R., Bijma, J., & Hemleben, C. (1997). Population dynamics of the planktic foraminifer Globigerina bulloides from the eastern North Atlantic Deep Sea Research Part I: Oceanographic Research Papers, 44 (9-10), 1701-1713 DOI: 10.1016/S0967-0637(97)00036-8

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Friday Fellow: Glacial calanus

by Piter Kehoma Boll

Today’s Friday Fellow comes swimming tinily through the freezing waters in the north. It is a small crustacean, more precisely a copepod, and its name is Calanus glacialis. It lacks a common name, but I adapted it as the “glacial calanus”.

Tiny, but beautiful. Credits to University of Alaska Fairbanks*.

Tiny, but beautiful. Credits to University of Alaska Fairbanks*.

Found in the Arctic Ocean and the northernmost areas of the Atlantic and Pacific Oceans, the glacial calanus is one of the most abundant polar species of copepods and one of the main components of the zooplancton in this region. As a result, it is an important food source for other animals, such as fish, birds and even whales.

The life cycle of the glacial calanus varies from 1 to 3 years and depends on the temperature and food availability. Most of its development occurs in summer, when the water is warmer and there is plenty of food, which for our fellow consists mainly of algae, such as diatoms. In autumn, the glacial calanus starts to accumulate lipids and then migrates downwards to deep waters and becomes dormant to survive the long, dark and food-poor winter.

As its life cycle depends on such seasonal variations, global warming may have profound impacts on the populations of the glacial calanus and on that of other species that depend on it as food.

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Kosobokova, K. N. 1999. The reproductive cycle and life history of the Arctic copepod Calanus glacialis in the White Sea. Polar Biology 22:254–263. DOI: 10.1007/s003000050418.

Søreide, J. E.; Leu, E.; Berge, J.; Graeve, M.; Falk-Petersen, S. 2010. Timing of blooms, algal food quality and Calanus glacialis reproduction and growth in a changing Arctic. Global Change Biology 16:3154–3163. DOI: 10.1111/j.1365-2486.2010.02175.x

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