Tag Archives: plankton

Friday Fellow: Twisted-Spined Sponge Radiolarian

by Piter Kehoma Boll

Oh, it’s time for our next radiolarian. As as usual, it’s hard to find good information on any species. (If you work with radiolarians and have good available resources and nice species to suggest, please contact us!)

It’s hard to find pictures of live radiolarians, especially those identified to the species level, but one that I found is seen below and is called Spongosphaera streptacantha, or the twisted-spined sponge radiolarian, as I decided to call it.

4xspongospaerastreptacantha2014oct27

A nice photo of a liveSpongosphaera streptacantha. Extracted from Galerie de l’Observatoire Océanologique de Villefranche-sur-Mer.

The twisted-spined sponge radiolarian is found in warm waters in the Atlantic and Pacific oceans (perhaps the Indian too?) and, as one can notice, may have a diameter of more than 1 mm if we count the longest spines. As with most radiolarians, the cell of this species has two concentric shells and a set of spines, which are 6 to 15 in number.

The food of the twisted-spined sponge radiolarian consists of smaller organisms, such as bacteria and algae, which it captures with the long rod-like pseudopods called actinopodia.

As with most radiolarians, the twisted-spined sponge radiolarian is understudied regarding its ecology. Let’s hope more people get interested in studying this fascinating group of organisms.

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References:

Kurihara, T.; Matsuoka, A. (2004) Shell structure and morphological variation in Spongosphaera streptacantha Haeckel (Spumellaria, Radiolaria). Science Reports of Niigata University (Geology), 19: 35–48. http://hdl.handle.net/10191/2141

Matsuoka, A. (2007) Living radiolarian feeding mechanisms: new light on past marine ecosystems. Swiss Journal of Geosciences, 100: 273-279. https://dx.doi.org/10.1007/s00015-007-1228-y

Radiolaria.org: Spongosphaera streptacantha. Available at: < http://www.radiolaria.org/species.htm?sp_id=90 >. Access on August 8, 2017.

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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.

Globigerina_bulloides

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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ResearchBlogging.orgReferences:

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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References:

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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*Creative Commons License
This work is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported License.

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