1. Division: Chrysophyta Class: Coccolithophyceae
Nannoplankton Coccolithophores
Kingdom: Protista
Division: Chrysophyta
Class: Coccolithophyceae
Introduction
They are unicellular marine planktonic protists (algae) with photosynthetic pigments and two flagella and haptonema (whip-like organ). It is surrounded by scales (plates) called COCCOLITHS.
Size: 5-60 µm, plate size = 10 µm

2. Live coccolith cell surrounded by scales after J. Young, NHM.

3. Coccoliths morphology
Plate (coccolith) consists of shields, plates, central area with or without bars, spine, distal side (outward) and proximal side
Morphological components of coccoliths

4. Some common recent coccoliths. From The Natural History Museum, London
Emiliana huxleyi
Reticulofenestra sessilis
Gephyrocapsa oceanic
Some common recent coccoliths. From The Natural History Museum, London

5. Coccolith Life-Style, Ecology and Reproduction
Coccolithophores live in the photic zone (the surface waters, where sunlight reaches) and are photosynthesising (autotrophic); so are at the bottom of the marine food chain, excellent food for herbivorous bacteria.
Some have flagella (whip-like appendages) so unlike plants, are capable of movement; furthermore, they don't simply float around, but can swim.
Although they are photosynthesising, some have been known to eat bacteria.
Reproduction is asexual-----simple division.
Sensitive for temprature, more abundant at the tropics cells/l.

6. Coccoliths and Sedimentation
After death, they sink by rate of 15 cm/day.
Factors of dissolution
They form high proportion
of carbonate in the sediments
Recent 26%
Chalk (Cretaceous) 26%
Eocene 90%
They are largest producers of calcium carbonate on Earth today, and probably have been since the Late Jurassic. They dump about 1.5 million tons yearly of limestone to the ocean floor.

7. Geologic history of coccoliths
Abundance of coccoliths in the stratigraphic column (Brasier, 1980).

8. Important coccoliths in the geologic history: a-b) Cyclococcolithina (Oligocene-Recent), c-d) Pseudoemiliania (Pliocene-Pleistocene), e) Helicopontosphaera (Eocene-Recent), f) Zygodiscus (U. Cret-Eocene), g) Prediscosphaera (Cretaceous), h) Braarudosphaeara (Cret-Recent), j) Rhabdosphaeara (Pliocene-Recent) and k) Discoaster (Mio-Pliocene). From Brasier 1980.