Tag Archives: natural sciences

Object of the Month – June 2020

June’s Object of the Month celebrates Volunteers’ Week. These fossils have been cleaned and recorded by two dedicated geology volunteers, helping to audit the thousands of fossils held in the Museum’s stores. The project is suspended at the moment, but we all look forward to getting back together when times are better.

These fossils are from the Red Crag layers, which are the reason Walton-on-the-Naze is famous for marine fossils. The sandy Red Crag rocks and fossils were laid down in the late Pliocene and early Pleistocene epochs between 3.3 and 2.5 million years ago, when a warm, shallow sea and bay covered most of Essex. The fossils have stained red-brown over time due to iron-rich water washing through the sandy rock.

The first fossil is a species of whelk, Neptunea contraria, which is still alive today (extant, rather than extinct). This species has an unusual left-spiral shell, hence the word contraria in its scientific name. Almost all species with a coiled shell have a right-hand spiral.

Neptunea contraria

Cardita senilis

Cardita senilis is a species of bivalve, a group which also includes oysters, mussels and scallops. These molluscs have a flattened body protected by two shells or valves joined by a hinge. A bulge near the hinge, called the umbo, is the oldest part of a growing shell, and is at the centre of the growth rings that can sometimes be seen on the surface.

Spinucella tetragona is an extinct species of predatory sea snail, in a group known as murex snails or rock snails. This species’ shells are highly ridged, but other extant species (such as Chicoreus aculeatus) have exaggerated and complicated patterns of spines on their shells, which makes them very popular with shell collectors.

Chicoreus a

Spinucella tetragona

Chicoreus aculeatus

Oyster: Ostrea species

Later Pleistocene fossils from Essex, such as the oyster, don’t really ‘belong’ here at all. They were brought south or churned up from older rocks by glaciers during the Pleistocene Ice Age, which lasted from 2.5 Mya to 12,000 years ago. They appear in glacial drift deposits left behind as the glaciers grew and shrank. This fossil of Chicoreus aculea is actually from the Jurassic period (201-145 Million years ago).

All images © Saffron Walden Museum, except C. aculeatus: H. Zell – Own work, CC BY-SA 3.0

Identification – flint, fossil sponge

Figure showing flint nodule from chalk

In Essex and south east England, almost every pebble on the beach and in gardens is flint. It’s a hard rock found in the Chalk, a soft, white, limestone layer that is up to 200m (600 ft) thick in north Essex and Cambridgeshire. In north west Essex, this chalk is between 90 million and 66 million years old and lies just below the soil, north of a line running from Stansted to Sudbury.

Diagram showing bedrock geology of Essex

Diagram showing the main bedrocks across a section of Essex. Chalk appears as the bedrock across northern Essex. Credit: reference 1.

Chalk started out as a thick mud on the floor of a tropical sea that covered most of Britain and north west Europe. This mud contained the remains of tiny sea creatures (plankton) which grew shells of calcium carbonate. When they died, these plankton and their shells fell to the sea floor to form a thick mud, which compacted into chalk over millions of years.

As it compacted, it squeezed out the seawater containing dissolved quartz, or silica (which comes from the skeletons of tiny sponges, a very simple animal).This silica was pushed out into gaps, cracks and burrows in the chalky mud to form nodules or layers of flint. These flints have a white outer layer (cortex), and are black inside. They can come in very complicated, bulging shapes, or with spikes, holes and cavities. Because of this, they can be easily confused with fossilised bones.

Figure showing flint nodule from chalk

An irregular flint nodule with a white cortex. Credit: reference 2.

Some flints do contain fossils, often urchins, or cockles or other small shellfish. Sometimes, the whole flint looks like fossil, and this may be because the silica that created it was forced into a hollow space in the hardening chalk which contained a sponge. Sponges are very simple animals which live on the sea floor. They still exist today, and the earliest known fossil sponges are  580 million years old.

The silica fills the gaps in the sponge’s skeleton and, over millions of years, the skeleton itself can dissolve away and be replaced by other minerals. This skeleton is a fossil, and the flint fills the spaces left by the soft parts of the animal after they rotted away.
Sponges are hollow tube or cone shapes and have no muscles, stomach, brain or nerves. They are filter feeders that catch bacteria and microscopic plants & animals from seawater that flows through tiny channels (pores) in their body.  Sponges are open at the top, and water currents flowing across the opening helps pull in water through the pores and remove it from the centre chamber, like wind blowing across a chimney.

Diagram showing water flow through a sponge's body

A simple diagram of a sponge’s body showing the pores in the sponge’s body, and the direction of water flow (blue arrows). Credit: reference 3.

Figure showing a living sponge

A living sponge, showing the typical hollow tube shape. Credit: reference 4.

The first sponge below is preserved in chalk and is a typical funnel shape. Some fossils may have a textured ring around the top, showing the rough pattern of the sponge’s surface and pores, like in the second photo.

Figure showing typical funnel shaped sponge

Fossil of a sponge (Ventriculites species) that lived in the Chalk sea. This sponge attached to the sediment with its branching roots. © SWM.

Figure showing rim imprint of a sponge's body in flint.

A flint nodule showing the imprint of the upper rim of a sponge’s body. Credit: reference 5

References

  1. Essex Bedrock, Essex Rock 1999. GeoEssex.org, retrieved 11:36, 24.4.2020
  2. © G Lucy. GeoEssex.org, retrieved 11:31, 24.4.2020
  3. Adapted from: Porifera_body_structures_01 By Philcha – Own work, CC BY-SA 3.0
  4. NOAA Photo Library reef3859 By Twilight Zone Expedition Team 2007, NOAA-OE. , Public Domain,
  5. Flint rim print. flint-paramoudra.com, retrieved 11:47, 24.4.2020

Identification – cattle hock bone

Photo of the calcaneus.

Cattle right-side calcaneus (heel bone)

The calcaneus in humans is the heel bone, and is the first point of contact with the floor when we walk. However, cattle are ‘nail-walkers’ – walking on the very tips of their toes with the rest of the foot held off the ground. This means the first joint from the ground on the hind leg is the ankle (hock), not the knee, which is why it bends in the opposite direction to our knee. The knee is further up the leg, almost hidden by the leg muscles, while the hip is very high up, just below the base of the tail.

Diagrom to show position of hock in cattle leg

The hock bone (calcaneus) is shown by no. 32 (bottom right). 31 shows the ankle joint and 30 shows the knuckles of the toes. 27 shows the knee joint (bottom middle). Image credit: reference 1.

The bovine foot has 15 bones, grouped into 7 tarsals (talus, calcaneus, and five others), 2 metatarsals (running from the tarsals to thethe two toes). These correspond to the 3rd and 4th metatarsals in human feet The big toe has the first metatarsal). The cow has 6 phalanges (three in each toe).
For comparison, humans have 26 foot bones, comprising 7 tarsals, 5 metatarsals (one leading to each toe) and 14 phalanges (two for the big toe and three for every other toe).

Diagrams showing skeletons of the cattle and human foot.

15-21 are the ankle bones, 23 and 24 are the metatarsals, and 26-28 show the three phalanges in each toe. The same bones are labelled in the human foot on the right. Image credits: references 2 and 3.

(The image above actually shows the front leg of a cow, with the wrist and not the ankle bones, but the other bones are generally the same.)

Photo of the calcaneus.

The original bone I was asked to ID. © Saffron Walden Museum.

In life, this cattle calcaneus is from the right hock and has the smooth side faces outward to the right, as in the photo above. The shaft of the bone is then pointing up and back, toward the tail of the animal, to form the distinctive point of the hock in the cow’s leg (no. 32 in the first diagram). The top of the bone  is the attachment point for the large muscles of the lower leg. These are the gastrocnemius and soleus, (the ‘calf muscles’ in humans).

Some of the more fragile edges of this calcaneus are missing, but you can still see the main features.

This photo is pretty much a close-up of the photo above, from the bottom end. © Saffron Walden Museum.

In the photo, the letter A shows a smooth articular surface for the 3rd and 4th metatarsals, and B is one of the articular surfaces with the talus. C is a dome-shaped articular surface for the lateral malleolus, a bone on the outer edge of the hock.  The roughened depression (D) in the centre of the plate is called the tarsal sinus, and is mirrored by a similar area on the talus. This cavity houses blood vessels, fat, nerves, and a series of ligaments which hold the tarsal bones together.
The talar shelf (E), is at the near end of the shaft, and helps support the talus bone which sits above it. There is also a groove (F) for the tendon of the flexor digitorum lateralis muscle, which bends the toes.

 The calf muscles which attach to the top of the bone help straighten the leg when walking and running, while the length of the bone acts as a lever to amplify their effect and increase make the movement more efficient This is especially important in animals such as cattle, whose ancestors and wild relatives migrate across continents and run to escape predators.

 – James Lumbard, Natural Sciences Officer.

 

References

1. Domestic_animals;_ _history_and_description_of_the_horse,_mule,_cattle,_sheep,_swine,_poultry,_and_farm_dogs,_(1858)_(14598393827)
By Internet Archive Book Images – https://www.flickr.com/photos/internetarchivebookimages/14598393827/Source book page: https://archive.org/stream/domesticanimalsh00alle/domesticanimalsh00alle#page/n51/mode/1up, No restrictions, https://commons.wikimedia.org/w/index.php?curid=44520464

2. Cattle hock skeleton diagram © https://www.dcfirst.com/cow_skeletal_anatomy_poster.html Accessed 31.3.2020.

3. BruceBlaus. :Blausen.com staff (2014). “Medical gallery of Blausen Medical 201”. WikiJournal of Medicine 1 (2). DOI:10.15347/wjm/2014.010. ISSN 2002-4436. / CC BY 3.0

Identification – Limonite

Yellow limonite on brown goethite.

Limonite (pronounced “lime-on-ite”) is an iron ore similar to the more well-known iron oxides haematite and magnetite. It often forms as existing deposits of these other minerals react with water in an oxidation reaction, turning the iron oxide into iron oxide-hydroxide. This interrupts the regular crystal structure and opens up microscopic gaps that trap other water molecules in positions where they can’t chemically react and bond with the iron atoms. Water which forms part of the molecular structure of in this way is called ‘water of crystallisation’.

Yellow limonite on brown goethite.

Limonite can be ground up to produce the pigment yellow ochre, famous from prehistoric cave paintings. This sample from the Museums’ mineral collection has yellow limonite on brown goethite, another form of iron hydroxide.
Image: © Saffron Walden Museum.

Scientifically, limonite does not meet the criteria of a ‘true’ mineral, which must have a consistent chemical formula and molecular crystal structure. Because limonite forms as a replacement for several other minerals, this means that the crystal structure is not consistent. Variations in the original mineral, the compounds dissolved in the water and the environment where it forms, also mean the relative amounts of iron oxide, iron hydroxide and water of crystallisation are not constant either.

Four small, rounded pieces of limonite

These pieces of limonite were originally pieces of the gemstone garnet. Iron-rich water filtering through these stones replaced the original garnet mineral with limonite, keeping the shape.
Image: Eurico Zimbres FGEL/UERJ CC BY-SA 2.0 br (Wikimedia Commons)

Limonite may be any colour from a rich yellow to a dark brown, and was used historically to make the yellow ochre pigment which is still produced in this way in Cyprus. Despite this variation in colour, an easy way to distinguish it from haematite is the ‘streak test’. This can be used to separate many minerals which may appear similar to the eye, by rubbing the mineral along a piece of un-glazed white porcelain. Limonite will leave a yellow-to-brown streak, whereas haematite produces a red streak.

Two forms of haematite leave a rusty red streak on ceramic, central.

Two different forms of haematite both leaving a rust-red streak.
Image: KarlaPanchuk [CC BY-SA 4.0] (Wikimedia Commons)

Deep red botryoidal (grape-like) haematite.

This is an easily-recognised form of iron oxide, haematite. The rounded, bulbous form is described as ‘botryoidal’, meaning grape-like in Greek.
Image: © Saffron Walden Museum

 – James Lumbard, Natural Sciences Officer.

Identification – Ammonite in sandstone

One of the most interesting parts of working in museums is helping people discover something new (and I usually learn something new myself). A really important way for museums to do their job as a welcoming public source of information is by identifying mystery objects that you might find on a walk, on a seaside holiday or even in your garden or attic.
Anyone can bring in an item for us to identify, for free, and you should have an answer within a few weeks. It might look a bit like this:

Ammonite in sandstone

This piece of stone is a Jurassic fine-grained sandstone or sandy limestone, which may be from the Lias Group rock unit found on the Dorset coast, although it has a sandier appearance and rougher texture than the rocks usually found in this formation. If it is from the Dorset Lias formation, the rock is roughly 195 to 200 million years old, and the fossils it contains would be a species of Promicroceras ammonite, which are common along the Dorset coast.

Fossil of a Promicroceras ammonite.
Image: Ammojoe CC BY-SA 3.0 (Wikimedia Commons)

The bristleworm, Polydora ciliata. Image: Yale Peabody Museum of Natural History [CC0] (Wikimedia Commons)

 

 

 

 

 

 

The surface pattern of pores in the rock was made much more recently. They were probably made by a species of Polydora worm, probably Polydora ciliata. P. ciliata is a small, rock- or shell-boring worm which can grow up to 30mm (1 1/8 in.) long, and is also known as a bristleworm.

P. ciliata burrows in stone. Image: Rosser1954 CC BY-SA 3.0 (Wikimedia Commons)

Bristleworms are thought to burrow into rock or shell by scraping away at the surface using specialised bristles on the fifth segment of its body, although it may also secrete chemicals such as weak acid to help. It digs a U-shaped burrow, which appears on rocks as distinctive small slots or a ‘sunglasses’ shape.

 – James Lumbard, Natural Sciences Officer.

 

Object of the Month – February 2020

Snowy owl from front left angle. White breast plumage, with brown bars to sides and legs. Brown spotted plumage on wings. Mounted on a wooden post. Against a dark grey background.
Snowy owl from front left angle. White breast plumage, with brown bars to sides and legs. Brown spotted plumage on wings. Mounted on a wooden post. Against a dark grey background.

A female snowy owl in the Museum’s collections. Image: © Saffron Walden Museum.

Snowy Owl

A female snowy owl, Bubo scandiacus. Female snowy owls have spotted and striped plumage (above), while the male bird is almost pure white (below, left). Snowy owls live in the Arctic Circle where they hunt for food over tundra and upland moors. These impressive predators eat lemmings and other rodents, birds and rabbits, and only very rarely visit the far north of Britain. This mounted skin was donated to Saffron Walden Museum in 2003 for the Education collection. It has come out of the store for Museums at Night, exhibitions and teaching sessions.

A snowy owl from front angle. Pure white plumage of male, with a few dark spots visble on left wing. Against a pale background.

A male snowy owl. Image: Barry Kaufmann-Wright © Saffron Walden Museum.

An eagle owl from front left angle. Tawny under-plumage with patterns of dark brown and pale grey in bars and stripes. Vivid orange iris to eyes, and large horn-like feathers. Perched on a wooden post. Against a snowy backdrop.

An eagle owl. Image: Kamil. Corrections Piotr_J [CC BY-SA 3.0] (Wikimedia Commons)

Did you know?

All living things have a common name, like ‘snowy owl’, and a scientific name. The scientific name is a combination of two words which are only used for that species. Humans are Homo sapiens, and our extinct close relatives the Neanderthals are Homo neanderthalensis. We are different species in the same genus, Homo.
But scientific names can change. In 2004, the scientific name of the snowy owl was changed from Nyctea scandiaca to Bubo scandiacus, after years of research on their genetics and the shape of their bones. This showed that they were more closely related to horned owls and eagle owls (above, right), and should use the same genus name, Bubo.

You can see the snowy owl as Object of the Month until 29th February.

Object of the Month – September 2019

September’s Object of the Month is a wax model of Pestle Puffball fungus, Handkea excipuliformis, found growing under Scots pine trees on a road to Newport, Essex by George Maynard between 1880 and 1904.

Pestle Puffball Fungus

This common fungus can be seen from August to November. It grows in woods, grassland, heaths and on waste ground. The fungus is 8 to 20 cm tall. It is white at first and turns brown as it ages. Initially it is covered in soft, pointed warts which all fall off to leave a smooth surface. The upper, rounded section, 3 to 12 cm across, is the head which contains the spores. The lower, straight section is the stem which soon develops a wrinkled skin.

This puffball is edible when it is young and white, if the tough outer skin is removed. However, the older yellow, olive and brown fungi and stems can still be found in winter and summer and should not be eaten. You need an expert to identify edible fungi as mistakes can easily be made.

George Nathan Maynard

George Nathan Maynard was the first curator of Saffron Walden Museum. He was born in 1829 in the village of Whittlesford, Cambridgeshire. From a young age he showed a great interest in natural sciences, including botany, entomology and geology. George inherited his father’s shop but had to sell it in 1873. The family moved to Lambeth in London where he worked as a printer and his wife Elizabeth was a dressmaker. In 1880 he was employed as the first paid curator of Saffron Walden Museum.

As curator he reorganised the museum displays, recorded objects in accession registers and carried out conservation work to preserve the collections. During this time he made a collection of models in wax, modelled from fungus specimens collected in Saffron Walden, Newport, Debden and Little Chesterford.

In 1904 George died of respiratory problems at the age of 75. His son Guy took over as curator until 1920 when he left to become curator of Ipswich Museum.

Fungus Forays

Want to know more about mushrooms and other fungi? 

Wildlife organisations lead fungus forays in the countryside with experts who can help you to discover the fascinating world of fungi, and which ones are edible and which ones to avoid!

Sat 19 October Marks Hill Wood Nature Reserve, Basildon, Essex https://www.essexwt.org.uk/events/2019-10-19-fungi-foray

Sat 27 October Sandylay & Moat Woods, Great Leighs, Essex https://www.essexwt.org.uk/events/2019-10-27-fungus-foray-sandylay-moat-woods

September, October, November.  Lots of fungus meetings with the Essex Field Club, see their Events programme at http://www.essexfieldclub.org.uk/portal/p/Meetings+ahead

Object of the Month – June 2019

Did You Know?

The ‘cabbage white’ butterfly is actually two closely related species – the large white (Pieris brassicae) and the small white (Pieris rapae). Apart from the size difference, the large white has darker black wing spots, and a dark black band at the front of its wings. Both lay their eggs on cabbages in gardens, allotments and farms, as it is the preferred food of their caterpillars. The large white takes the outer leaves, while the small white prefers the soft inner leaves. The adult (imago) of both species often feeds on nectar from buddleia flowers.

Cabbage white butterflies “Insects Injurious to Vegetables”. SAFWM : 118007. © Saffron Walden Museum

The display has a male and female of each species, with the male at the top and female below. There is also a caterpillar of the large white butterfly, which is yellow and hairy, with black bumps on its skin. The small white’s caterpillar is pale green and hairless with a narrow yellow stripe on either side. The cabbage leaf in the box has some caterpillar feeding damage.

Caterpillar of the small white. CC BY-SA 3.0, Harald Süpfle.

Chrysalis of the small white. CC BY-SA 2.5, James Lindsey at Ecology of Commanster.

Life cycle

These butterflies have two ‘broods’ per year, and three in a good year. In the spring, butterflies which survived the winter as a chrysalis emerge as adults in April and May. They lay eggs in May and June (spring brood), which hatch into caterpillars in June and July. The caterpillars feed and grow quickly, and shed their skin 4 times as they grow. After about a month, the caterpillar finds a sheltered spot to transform into a butterfly in a process called metamorphosis. The caterpillar spins a pad of silk against the surface of its shelter, and sheds it skin again to reveal a hard skin (chrysalis), which has a small hook to keep it attached to the silk.

Adults emerge from the chrysalis about two weeks later, in July and August. They then lay eggs which develop into caterpillars through September and form chrysalises into October. The caterpillars go through a very slow metamorphosis to survive the winter, and emerge as adults the following April and May to start the process again.

Butterfly survival

On the right of the leaf are some cocoons and adults of a parasitic wasp which lays its eggs inside the caterpillars. After hatching, the wasp larvae feed on the caterpillar and eventually kill it, helping to control cabbage white numbers in a natural way. The adult wasp feeds on nectar.

Like many insects, these butterflies have declined in number recently. Currently, the large white and small white are not the focus of conservation efforts, but many other more specialist butterflies have declined severely or have gone extinct in Essex since 1900.
You can find out more about local butterflies in the Take Away the Walls exhibition at the Museum.

June’s Object of the Month was chosen by James Lumbard, Natural Sciences Officer.

Image credits

Pieris rapae caterpillar: James Lindsey at Ecology of Commanster [CC BY-SA 2.5 (https://creativecommons.org/licenses/by-sa/2.5)]. Accessed 11/06/2019.

Pieris rapae chrysalis: Harald Süpfle [CC BY-SA 3.0 (https://creativecommons.org/licenses/by-sa/3.0)]. Accessed 11/06/2019

Parasitic wasp Cotesia glomerata: Copyright © Albert de Wilde – All rights reserved http://www.ahw.me/img/sluipwesp4mm_grootkoolwitje01b.html. Accessed 11/06/2019.

Featured Image – Cabbage whites “Insects Injurious to Vegetables” on display in the Museum © Saffron Walden Museum

 

Object of the Month – May 2019

The Museum’s ‘Object of the Month’ display provides an opportunity to explore interesting and unusual objects from the stores. The object chosen by Sarah Kenyon, Natural Sciences Officer, for May 2019 is a moth. This leopard moth, Zeuzera pyrina, was found in a house at Elsenham, Essex in July 2012. After it was identified it was given to the Museum.

If you love butterflies and moths then May is the month to come to Saffron Walden Museum. This beautiful black and white leopard moth will be on display all month in the natural history gallery, where you can learn more about the species. Make sure you check out Curiosity Corner – peacock butterfly caterpillars will be on display and you can see them transform into adult butterflies during May.  On 17th May as part of the Wildlife at Night evening you can do moth trapping with the Essex Field Club.  See the moths that live in the Museum grounds before they fly back into the wild.

The polecat comeback

Object of the Month – February 2019

The European polecat, Mustela putorius, was thought to be extinct in Essex since 1880 thanks to persecution from gamekeepers. The first modern sighting was in 1999 near Wendens Ambo and there are now numerous records from north-west Essex, though only from roadkill specimens.

A mounted polecat skin from 1842 and a polecat skull, also from the 1800s.

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