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WonderPhytoplankton fact

Coccolithophores are tiny single-celled algae that cover themselves in intricate plates of chalk (calcium carbonate). Drifting in sunlit seawater in vast numbers, they link microscopic life to ocean chemistry and the global carbon cycle.

Coccolithophore

OceanBiologyClimateScience

The story behind the card

Each plate, called a coccolith, is a few thousandths of a millimetre across; it is built inside the cell and then pushed out to its surface. When coccolithophores die, their plates sink, and over millions of years thick layers of them have hardened into chalk: the White Cliffs of Dover are made largely of coccoliths laid down in the Cretaceous period, roughly 100 to 66 million years ago. The commonest species today, Emiliania huxleyi, forms blooms that turn the sea milky turquoise and can be seen from space. Coccolithophores take up carbon through photosynthesis, and their sinking plates carry carbon to the seabed, where scientists read their fossil remains to reconstruct past climates.

Türkçe oku
Kokolitoforlar, kendilerini ince işlenmiş tebeşir (kalsiyum karbonat) plakalarla kaplayan minicik, tek hücreli alglerdir. Güneş alan sularda milyarlarcası sürüklenir; mikroskobik yaşamla okyanusun kimyası ve dünyanın karbon döngüsü arasında köprü kurarlar.

Kokolit denen her plakanın çapı milimetrenin birkaç binde biri kadardır; plaka hücrenin içinde yapılır, sonra yüzeye itilir. Kokolitoforlar ölünce plakaları dibe çöker. Milyonlarca yılda kalınlaşan bu katmanlar sertleşip tebeşire dönüşmüştür: Dover'ın Beyaz Kayalıkları büyük ölçüde, yaklaşık 100 ile 66 milyon yıl önce, Kretase döneminde birikmiş kokolitlerden oluşur. Bugün en yaygın tür olan Emiliania huxleyi, denizi sütlü bir turkuaza boyayan ve uzaydan görülebilen kitlesel çoğalmalar yapar. Kokolitoforlar fotosentezle karbon alır; batan plakaları da karbonu deniz tabanına taşır. Bilim insanları oradaki fosillerinden yararlanarak geçmiş iklimleri yeniden kurar.

Sources and further reading

Background reading: Coccolithophore
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