We are showcasing our microfossil tree on the Climate Change Station at the annual Science Uncovered event on Friday 26 September. This remarkable item was created and generously donated by Chinese scientist Zheng Shouyi, and in this post I'll explain how it demonstrates the beauty and composition of foraminifera, climate change and our unseen collections.

The microfossil tree will be on display at Science Uncovered on the 26 September.

A 6ft aluminium stand with 24 arms hangs 120 plastic models of different species of foraminifera and was generously donated to us earlier this year by Zheng Shouyi of the Institute of Oceanology, Chinese Academy of Sciences, Qingdao. She is famous for commissioning and overseeing creation of the famous Foraminiferal Sculpture Park. The models on our tree are magnified 10s to 100s of times.

Species modeled are mainly living examples present in the China Sea and described by Zheng Shouyi during her research. Fossil forms have also been chosen to represent the remarkably wide range of shell compositions and structures created by the single-celled foraminifera. Shouyi was originally inspired by the famous French palaeontologist Alcide d’Orbigny, who created sets of models in 1826 to illustrate the first classification of the foraminifera.

I have chosen four things that our tree shows. There are undoubtedly more and we look forward to discovering them over the next years. Here they are:

1. The beauty of the foraminifera

Everyone who sees our tree remarks how beautiful it is. Zheng Shouyi created them for 'the public to have a share of the diversified and exquisite beauty of the one-celled foraminifera endowed on them by Mother Nature, to inspire scientific, aesthetic and cultural innovations'. Science Uncovered is therefore the perfect venue for us to show this tree in public for the first time.

2. Foraminiferal shell composition

The colours, lustre and textures of the models reflect differences in wall structure and chemical composition of the foraminifera. Most foraminifera are composed of calcium carbonate but the agglutinating foraminifera construct their shells from grains of sand or any suitably sized items available from the ocean bottom. Models representing agglutinating forms on the tree have a sandy texture and mainly a sandy light brown colour to reflect this.

Other forms of calcium carbonate secreted by foraminifera include the porcellaneous varieties where the models appear shiny and milky white. Some calcareous foraminiferal shells of are transparent and glassy while others have translucent white shells that can be perforate or imperforate.

Models of Cribrohantkenina inflata Howe and Hantkenina alabamensis Cushman.

3. Climate change

Two species of hantkeninid foraminifera present on the tree illustrate an interesting story of climate change relating to the fossil record of foraminifera. The extinction of the hantkeninds at the Eocene-Oligocene boundary (about 33-34 million years ago) is thought to relate to fluctuations in climate related to global cooling.

Because planktonic foraminifera, such as the hantkeninids, secrete their shells from the ocean water they lived in, studying isotopic changes in their shell composition can provide information about past changes in ocean composition that are linked to climate. The modern day distribution of planktonic foraminiferal species is often latitudinally restricted, with some preferring cold polar rather then warmer equatorial waters. Studying assemblages of different species in a sample can therefore give past indications of climate.

Zheng Shouyi's model of Globigerinoides sacculifer (Brady, 1877) alongside (right) scanning electron microscope images of lectotypes and paralectotypes of the same species from our collections. Images published by Williams et al. (2006) in a paper that I co-authored.

Large numbers of specimens can be recovered from relatively small core samples drilled from the ocean bottom, such as the core that we are showing at the Science Uncovered Event. This makes planktonic foraminifera key to studies in past climates based on the marine stratigraphical record.

4. Our type collections

The tree includes 11 examples of species for which we hold the type specimen. These include examples from historically significant collections such as Brady’s foraminiferal types from the Challenger Collection, the Heron-Allen and Earland Collection and W. K. Parker's types.

We think our microfossil tree fits perfectly with the idea behind Science Uncovered, where scientists come out from behind the scenes to share science and collections that the public would not normally see or perhaps realise existed. If you are in London on 26 September we hope you can come and join us on the Climate Change table under the Darwin Centre cocoon for Science Uncovered.

On Friday 27 September the doors of the Museum will remain open after usual closing time and scientists like me will be available to talk about our science, show specimens and chat at Science Uncovered, our EU funded Researchers' Night. Presentations in the Nature Live Studio will also be held and it will be possible to book tours to areas of the Museum not normally open to the public.

This year Tom, Steve and I are on the Climate Change table in Waterhouse Way demonstrating some deep sea cores taken from the Atlantic Shelf SW of Ireland. The cores were drilled through sediments representing the last ice age. Information on the distribution and composition of microfossils, allied with other scientific data, shows six 'Heinrich Events' through the last glaciation. These events are thought to relate to climate related cyclic episodes when icebergs broke off glaciers and traversed the North Atlantic.

Science Uncovered 2012 welcomed an incredible 8,523 visitors over the night who spoke to over 350 scientists. If it proves to be as successful as last year where we presented our microfossil zoo or 2011 when I was able to use a giant plasma screen to show some of my research then it promises to be an amazing night. Do come and join us if you can.

This core from the Atlantic SW of Ireland represents the last major glacial period showing glacial dropstones from colder periods (left) and white sections composed almost entirely of warm water microfossils (right). The green packets (far right) and plastic sleeve maintain an oxygen free environment and prevent mold growth on the core.

To celebrate the United Nation's Year of Biodiversity last year, the Museum published details of a different species every day on its web site under the title Species of the Day. These records were delivered last week to another web site The Encyclopedia of Life. Each species was chosen and written about by a museum scientist so this week's blog is to point you in the direction of the microfossils which were chosen for their importance in studies on climate change, ocean acidification, north sea oil exploration and the fossil record of sexual reproduction. Follow the links below to find out more about each species and the groups to which they belong.

Emiliania huxleyi

Emiliania huxleyi is a coccolithophore which is a unicellular plant that lives in the upper layers of the ocean and forms tiny calcareous coccolith plates like the ones you can see above. These are artificially coloured images from a scanning electron microscope. This very high powered microscope is needed as they are only tens of microns in size and as a result are usually referred to as nannofossils. The ones above are only slightly larger than a thousanth of a millimetre in size. If you were to dip a bucket in the ocean you could find literally tens of thousands of these types of cells. In early summer, E. huxleyi forms enormous blooms across the northwest European shelf that can be seen from space. Coccoliths are susceptible to changes in climate and ocean acidification. This, combined with an excellent fossil record makes them an essential group in the study of recent changes to our oceans and environment.

Harbinia micropapillosa

Harbinia micropapillosa is an ostracod, a microscopic crustacean with two calcareous shells. Ostracods can be found in virtually any current aquatic environment and very rarely on land in damp habitats near to water. They have an extensive fossil record because their two shells preserve well as fossils but usually the soft body parts decay soon after death. H. micropapillosa is exceptional because the soft body parts have been preserved in a rock formation that is roughly 140 million years ago. Recent analysis using new techniques has shown the reproductive organs of this ancient organism are identical to those of present day ostracods and suggest that they reproduced using giant sperm back in the Cretaceous period. If you can't wait to find our more about this interesting fossil then follow the link above. However, I will be expanding the story of these important specimens in our collections as the subject of a future blog.

Nannoceratopsis gracilis

Nannoceratopsis gracilis is a dinoflagellate cyst from the Jurassic period about 145-200 million years ago. Dinoflagellates are marine photosynthetic algae that play an important role at the base of the food chain and the carbon cycle. At stages throughout their life cycle they form resistant organic cysts that can be found in the fossil record by dissolving suitable rocks in nasty acids like hydroflouric acid. Nannoceratopsis is one of the earliest forms of dinoflagellate cyst so studies of this genus can tell us a lot about the early evolution of dinoflagellates. The shape is also very distinctive and easily recognisable. N. gracilis can be found in rocks 168-185 million years old and can therefore be used, on its own or in association with other fossils, to accurately date rocks.

Nummulites gizehensis

I mentioned Nummulites gizehensis is a member of the Foraminifera in my second blog and showed a picture of the pyramids at Gizeh that are constructed from rocks that contain this species. The genus Nummulites is a member of a group called the "Larger Foraminifera" that build multichambered shells up to 15cm in size despite being a single celled amoeba. The chambers like the ones shown above can only be seen by breaking the shells apart or making specially oriented thin sections of the rocks they are found in. Sometimes symbiotic green algae also lived in the chambers, providing products of photosynthesis to the amoebe while using the shell as protection. N. gizehensis lived during the Middle Eocene epoch about 37-48 million years ago, in shallow marine conditions and can be used as a marker to show the age of rocks that contain them, particularly in the oil region of the Middle East.

Finally a big thank you to my former colleagues Jeremy, Susanne and Clive who originally wrote about three of these beautiful microfossil species of the day.