Category Archives: Natural History

Object of the Month – September 2023

Image (above): Spiny Seahorse, Hippocampus guttulatus    SAFWM : 1975.68 ©

September’s Object of the Month is a Spiny Seahorse found on the east coast of England at Skegness, Lincolnshire in 1904. The dried specimen was donated to the Museum by a resident of Saffron Walden. It is 12 cm long from head to tail.

British Seahorses

There are two species of British seahorse. The Spiny Seahorse, Hippocampus guttulatus, and the Short Snouted Seahorse, Hippocampus hippocampus. The main difference between the two species is the length of the snout. The Spiny Seahorse has a longer snout and spines on the back and the head. They can grow to 18cm in length and live for 10 years.

Seahorses live in shallow coastal waters around the British Isles, up to the Shetland lsles, and Ireland. A Short Snouted Seahorse was seen for the first time at Harwich Harbour, Essex in 2023. They are poor swimmers and rely on their prehensile tail to cling onto seaweed and seagrass to stop themselves being swept away. A small dorsal fin beats 35 to 70 times per second to provide weak forward propulsion. Seahorses feed on small shrimp, crab and plankton. Their eyesight is good and the flexible snout can get into crevices in rocks. Prey is sucked up through the snout because seahorses do not have teeth. In winter they migrate to deeper water and anchor themselves to rocks or seaweed to ride out storms.

Seahorse facts

Fish: Seahorses are fish! They are related to pipefish and sea dragons.

Pregnancy: the males get pregnant.

Seahorses are the only animal with a true reversed pregnancy. The female transfers the eggs to the male with her ovipositor. He fertilises them and keeps them in his brood pouch to grow. Then he gives birth to live young called fry. Seahorses are monogamous and have one partner for the breeding season from April to October. It is not thought that they mate for life now.

Colour: seahorses can change colour like chameleons.

This helps camouflage them to hide from predators and in courtship. Each day the female meets the male in his territory, they change colour and perform a dance where they may circle each other, or an object, and hold tails. 

Threats

Seahorses are endangered. They are legally protected by CITES (Convention on the International Trade in Endangered Species) and The Wildlife and Countryside Act. It is illegal to import, kill, capture or disturb a seahorse.

Habitat destruction

Seagrass meadows can be destroyed by anchors, fishing nets, dredging, drilling for oil and pollution. 92% of meadows have been destroyed. Marine Protect Areas are being set up around Britain to protect biodiversity.

Seahorses are captured for the pet trade or killed and dried for use in traditional medicines or sold as souvenirs.

Climate change

A marine heatwave around Britain in April 2023 saw seas reach their highest recorded surface temperature of 210C. Seagrass meadows are stressed by heat. Ocean heatwaves cause mass mortality of marine plants and animals and the collapse of food chains. Sea ice also is melting and ocean circulation has slowed down due to higher global temperatures.

If ocean currents change direction or stop the supply of plankton that seahorses depend on for food may be disrupted.

How can you help?

Never buy souvenirs of dried sea creatures such as seahorses, starfish or shells which are homes for hermit crabs.

Reduce your use of plastics and buy fish that is caught sustainably.

Use eco moorings when sailing to anchor your boat.

Support a marine conservation charity such as The Seahorse Trust www.theseahorsetrust.org Donate or volunteer and you can even adopt a seahorse!

Report sightings of seahorses to The Seahorse Trust via the British Seahorse Survey website

www.theseahorsetrust.org/conservation/british-seahorse-survey/

Image (above): Spiny Seahorse, Hippocampus guttulatus    SAFWM : 1975.68 ©

 

Object of the Month – June 2023

This is the cast skin / exoskeleton (exuvia) of a dragonfly larva, found in Elsenham in August 2005. The shape of the eyes and the length (40mm) suggest it’s a hawker dragonfly, while the finder’s description of the adult dragonfly being green and yellow means it is probably a southern hawker, which are common in July and August.

Dragonfly exuvia © Saffron Walden Museum

These dragonflies spend 2 or 3 years as a larva, or nymph, living underwater, before coming above water to shed their skin and emerge as an adult.

Southern hawker dragonfly by Tom Wiersma, via Wikimedia Commons.

Dragonflies, like all insects, have a hard exoskeleton which does not grow with them. After hatching from an egg, dragonfly nymphs gradually grow into adults through a series of moults to shed their skin, which allows it to grow in size each time, emerging as an adult directly from the last moult.
The nymphs look similar to the adult, with a long body and six legs. Nymphs in the last stages of growth have wing buds that you can see on this specimen.
This method of growth, through nymphs with wings developing on the outside, is called incomplete metamorphosis.

This is different from other insects including flies and butterflies, which hatch as maggots or caterpillars. This is the larva of the insect, and it looks very different from the adult. The larva in these insects also has to moult to increase in size, but the final moult is different. It creates an inactive pupa (called a chrysalis in butterflies) where the final radical transformation into the adult takes place. This method of growth from larva to pupa to adult is called complete metamorphosis.

Visit the Museum to learn more about the two types of metamorphosis in the Discovery Centre, and take a closer look at two exuviae from our Malaysian stick insects.

Exuvia of female Malaysian stick insect © Saffron Walden Museum

Exuvia of male Malaysian stick insect © Saffron Walden Museum

 

 

 

 

 

 

 

Image credit:
Female Southern Hawker – Tom Wiersma, CC BY-SA 4.0 <https://creativecommons.org/licenses/by-sa/4.0>, via Wikimedia Commons. Accessed 25.5.2023.

 

 

Object of the Month – May 2023

Fossil Sponge from Radwinter

Saffron Walden Museum offers a free identification service for objects from north-west Essex. People often find interesting stones in their garden or in fields. Many of these are flint nodules. Flint is a hard rock that comes from chalk, a soft white limestone that is 200 metres thick in north Essex and Cambridgeshire. Chalk was formed as a limy mud on the floor of a tropical sea that once covered most of Britain and north-west Europe during the Cretaceous period 65-145 million years ago. The sea water contained dissolved quartz, or silica, originating from the skeletons of tiny sponges. As the mud was compressed into chalk the silica became concentrated as nodules or layers of flint. When the chalk became exposed as dry land, erosion by rivers released the flint and redeposited it as thick layers of gravel. Flint is often found as brown, iron-stained pebbles. Unweathered nodules, fresh from chalk rock, are black with a white outer surface.

 

 

 

 

Fossil Sponge, Radwinter

Occasionally flints contain fossils of sea urchins or cockle shells. You can see some of these fossils in the Museum’s geology gallery – The Earth Beneath Your Feet. This circular stone from Radwinter is a sponge called Porosphaera globularis which is fossilised in flint rock. The animal lived in the Chalk Sea that covered Essex 80 million years ago, during the age of the dinosaurs. The flint has been stained brown by iron in the soil. Circular flint nodules are often fossilised sponges, or they have formed around the nucleus of a sponge. The size can vary, from flints the size of musket balls to nodules the size of cannon balls.

Identification – deer calcaneus

It looks like a calcaneus bone, which in humans and other primates is the heel bone of the foot. This one is from a left leg. In most non-human mammals it looks like it’s halfway up the hind leg, but serves the same purpose as the attachment point of the calf muscles (gastrocnemius and soleus), and its length acts as a lever to make the muscle action more powerful when flexing the foot towards the ground.

Black background with a tape measure vertical, centre-left and a bone vertical, centre-right. the bone is wider top than bottom, with points at top and top left.

Mystery bone © S Moore

As a tentative ID from reseraching from my desk in the UK  is white-tailed deer (Odocoileus virginianus), based mainly on its size and coming from Mississippi. The bone is a bit worn so some of the sharper and edges and points are missing, but the overall shape of the wide end looks like it matches the photos here https://www.boneid.net/search/?product_cat=wt_deer&pa_anatomic-elements=calcaneus&order=DESC. The length is about right too, if you imagine adding back on the points and edges that have been worn away.

For much more information on the calcaneus bone, see this ID of a cattle calcaneus Identification – cattle hock bone

Object of the Month – February 2023

A picture of a taxidermy common eider duck. It has a black cap to its head, a yellow beak, white head, neck and back and a black underside, with yellow legs and feet. Against a painted backdrop of a rocky mountain and hazy clouds.

This month we’re celebrating the Lost Language of Nature project, putting the finishing touches to this common eider. James and Charlotte have cleaned its plumage, repainted its beak and feet, and refreshed its base to help preserve it for future exhibitions.

A picture of a taxidermy common eider duck. It has a black cap to its head, a yellow beak, white head, neck and back and a black underside, with yellow legs and feet. Against a painted backdrop of a rocky mountain and hazy clouds.

Common eider mounted skin

Eider ducks are famous for their soft downy feathers which help keep them warm in freezing conditions. ‘Down’ comes from the Old Norse word ‘dúnn’, the word for the fluffy feathers of young birds and the same feathers which insulate adult birds. In adults, the down is hidden beneath the larger contour feathers which give birds their colour, patterns and shape.

A fluffy white feather on a black bacground

Down feather © Wouter Hagens, CC BY-SA 4.0, via Wikimedia Commons

These wild ducks can be ‘farmed’ sustainably for their down feathers, which are taken from the nests once chicks have fledged. This down is used to make traditional eiderdown pillows and quilts. In the UK, eider ducks are sometime called St Cuthbert’s duck or Cuddy duck, according to the belief that St Cuthbert’s holiness protected Farne island and its population of eider ducks.

Grassy and muddy ground wiht a grey nest of fluffy eider down. Three eggs are in the middle of the nest.

Eider nest © Paul Gierszewski (Gierszep), CC BY-SA 4.0, via Wikimedia Commons

Saffron Walden Museum wants to hear your stories about wildlife and nature in your life, or that you know from parents and grandparents, to help create more interesting, relevant and diverse displays in the future. Fill in a postcard in the Museum to join in or search online for ‘Lost Language Saffron Walden Museum’.

Learn more about this Object of the Month in the Museum throughout February.

Various English dialect words and non-English translations for 'eider'.

Identification – Fossil sponge in flint

Some flints do contain fossils, or look like whole fossils. Fossils inside the flints are often sea 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 filled by a sponge. 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.

A grey, funnel-shaped fossil on a wooden surface

Typical funnel-shaped sponge, fossilised in flint. © L Hodgson.

The shape of this piece of flint looks a lot like a small sponge that lived on the sea floor, and was fossilised in flint as the thick mud solidified into chalk. It may have patterns inside it that show the structure of the sponge’s skeleton. The wiggly line around the widest part of the flint shows the top rim of the sponge and the rough texture of the line is the surface texture of the sponge preserved as a fossil.

More info on flint and chalk in Essex in this post from 2020. https://saffronwaldenmuseum.swmuseumsoc.org.uk/identification-flint-fossil-sponge/

Object of the Month – October 2022 – Alpine Swift

Dark alpine swift (Tachymarptis melba) on a white perch

This month we’re celebrating the Lost Language of Nature project, with repair work to this alpine swift. This bird has been cleaned and had its base refreshed to help preserve it for future exhibitions, and will be on temporary display in the Museum throughout October. Alpine swifts spend the warmer months around the Mediterranean Sea and further east, or in southern Africa, and spend the cooler months in parts of east and west Africa. This one was found or killed in Hinxton, Cambridgeshire, in 1832. They are related to the common swifts we see in Britain but are noticeably bigger. Old beliefs about swifts said that they had no feet, and the scientific name of the common swift and related birds – including the alpine swift and hummingbirds – even comes from the Ancient Greek for ‘without feet’.

We’d love to hear your stories about wildlife and nature in your life – rhymes, songs, saying, or names for plants and animals that you know from parents or grandparents. Fill in one of our special postcards in the museum, or click here.

Anyone and everyone has a story to tell, and your stories will help us create more interesting and relevant displays for everyone who comes to the museum in the future.

Dark alpine swift (Tachymarptis melba) on a white perch

Alpine swift after conservation work

Swift work

This alpine swift is 184 years old and needed a good clean with special smoke sponge to remove dust and dirt from its feathers. Conservation work like this is always done very carefully, trying to avoid harmful chemicals, and using techniques that can be easily reversed if needed.
We cleaned its glass eyes with rubbing alcohol (isopropyl alcohol) and a hand-made cotton swab. The dust and dirt on the feathers can allow mould to grow, which damages the feathers because it produces acidic waste products. This bird had some possible mould patches underneath its tail and on top of its right wing, which we also cleaned with rubbing alcohol to kill and remove the mould.

We removed the swift from its base to paint the base white – you can see green splashes on the bird’s feet where the base was painted green in the 1930s without removing it. Birds are attached to their stands using wires from the bottom of the feet, and we had to cut one to remove the base.

Underside of bird with feet upwards. Wire protruding from foot on left of picture.

Alpine swift removed from perch, wire on right foot cut.

A new wire then needed attaching so the bird could be put back on its perch. We wound green florist’s green wire around the cut wire underneath the swift’s foot, and secured the new wire to its leg using Japanese tissue paper and conservation-grade PVA glue like tiny papier-mâché.

Underside of bird with feet upwards. New wire protruding from foot incentre of picture.

Alpine swift removed from perch, new wire on left foot.

Object of the Month – September 2022

The Museum’s ‘Object of the Month’ provides an opportunity to explore interesting and unusual objects from our stores. 

To celebrate harvest time our ‘Object of the Month’ for September is the nest of a Harvest Mouse, Micromys minutus, made of woven grass. It was found in a clump of Knotgrass at Sweetings Meadow nature reserve, near Thaxted in 1999. The Harvest Mouse is Britain’s smallest rodent. Weighing only 4 to 6 grams it is light enough to climb grass stems and reeds, using its paws and long prehensile tail to grip the stalks. 

This is our only mouse able to build nests by weaving living grass leaves together. In summer and autumn, the mice live above ground in camouflaged nests. Breeding nests are spherical and up to 10cm diameter in size to accommodate litters of two to eight young. Single mice build smaller, less robust nests up to 5cm in size. A Harvest Mouse survey in Essex found nests in the grass of roadside verges that bordered arable fields and in reedbeds, ditches, field edges and hedgerows. The nests may be sited up to a metre above ground in dense vegetation, or in the base of a tussock of grass.

Visit the Museum in September to see the Harvest Mouse nest on display, together with a photograph of another mouse with its nest in a barn taken by a local wildlife photographer. You can also find some tiny Harvest Mice on the Natural History gallery. 

Chosen by Sarah Kenyon, one of the Natural Sciences Officers at the Museum.

Harvest mouse nest SAFWM : 2001.180 

Saffron Walden Museum ©

Object of the Month – June 2022

June’s object of the month celebrates the Lost Language of Nature project, with repair work to this hen harrier. With Lost Language of Nature, we want to hear your stories about wildlife and nature in your life, or rhymes, songs and sayings for all kinds of animals that you might have heard from parents or grandparents. For example, different old names across the country for hen harriers include Blue sleeves, Vuzz kitt, Grey gled, Furze kite and Goss harrier; or Ringtail for females, like this fragile mounted skin. Head to our website for more information https://www.swmuseumlearning.com/the-lost-language-project

This bird came to the Museum in the 1800s, and was taken from the area around Saffron Walden. Today, hen harriers only live in the north of England, north Wales, in Scotland and on Scottish islands, including Arran and Orkney.

Hen harrier on temporary base during conservation work.

Hen harriers today

Hen harriers are one of the UK’s most endangered birds of prey, with only an estimated 545 breeding pairs left in the country. They are on the RSPB’s Red List of endangered species in Britain, but listed as ‘Least Concern’ globally by the International Union for Conservation of Nature.

Work carried out by the RSPB suggests that over 2,500 pairs could survive in the UK. They live in open areas with low vegetation, like heather moors.

Between 2014 and 2019, the RSPB ran the LIFE project to learn more about hen harriers in Britain, their movements throughout the year and to understand why their numbers are so low. They tagged over 100 birds that they tracked using satellites, and found that some fly 1000 miles to spend the winter in Spain and Portugal. Not all birds do this though – the brother of one of these wandering birds always stayed within 50 miles of where he hatched.

In the UK, hen harriers are protected under Schedule 1 of the Wildlife and Countryside Act, meaning it is illegal to kill, injure or capture the birds, their eggs or nests, or even disturb the birds and their young while they are nesting. Despite this, the study showed that the numbers of breeding hen harriers fell by 24% (about one-quarter) between 2004 and 2016. In particular, the project monitored seven Special Protected Areas in parts of the country where land is managed for driven grouse shooting. In these seven areas, hen harrier numbers fell by over 80%, which suggests that there is deliberate human action to reduce their numbers in these areas.

References

https://www.rspb.org.uk/birds-and-wildlife/wildlife-guides/bird-a-z/hen-harrier/

https://www.rspb.org.uk/our-work/conservation/projects/hen-harrier-life/about-the-project/

https://community.rspb.org.uk/ourwork/skydancer/b/skydancer

https://community.rspb.org.uk/ourwork/skydancer/b/skydancer/posts/hen-harrier-apollo-bomber-migrate-1000-miles-to-spain

https://www.rspb.org.uk/our-work/conservation/projects/hen-harrier-life/best-places-to-see-hen-harriersnew-page/

Object of the Month – May 2022

Butterflies to See in May

Two drawers of British butterflies are our ‘Objects of the Month’ for May. They contain some of the butterflies that you might spot visiting your garden or local park during May. These butterfly species are the Brimstone, Green-veined White, Holly Blue, Orange-tip, Peacock, Painted Lady, Red Admiral, Small White and Large White.  The drawers are from a wooden cabinet of butterfly specimens collected in Essex and other places in Britain between 1890 and 1968. The collection was donated to Saffron Walden Museum in 2002.

SAFWM : 2002.110.5 Butterfly cabinet drawer 5 containing Small Tortoiseshell, Peacock, Painted Lady, Red Admiral and Silver-washed Fritillary butterflies.

Butterflies that may hibernate over winter as adults in the UK include the Brimstone, Red Admiral, Peacock, Comma and Small Tortoiseshell.    This means they can wake up bright and early to make the most of sunny spring days. There are 59 species of butterfly in Britain, 57 that live in the UK and two regular migrants – the Painted Lady and Clouded Yellow.

Butterfly Conservation found that 76% of butterflies have declined in numbers and range (occurrence) over the last 40 years due to habitats being destroyed, pollution, weather patterns and climate change. Gardens and balconies are very important for butterflies because they are wildlife corridors. They cover a large area, which according to the RSPB is about 1,500 square miles or twice the size of Greater London. This habitat provides the flowering plants, such as Buddleia, that butterflies need for nectar, or nettles and thistles which are eaten by caterpillars.

 

SAFWM : 2002.110.2 Butterfly cabinet drawer 2 containing Small White, Green-veined White, Bath White, Orange-tip and Wood White butterflies.

What can you do to help?

Butterfly caterpillars need nettles, thistles and shrubs like Buckthorn to eat, so leave parts of your garden to get wild and overgrown.

Plant cornfield annuals and nectar rich flowering plants such as Buddleia, Lavender, Betony and Red Valerian to provide nectar for butterflies.

Take part in No Mow May or leave part of your lawn uncut until autumn.

Enjoy watching butterflies and do the National Garden Butterfly Survey.

 

SAFWM : 2002.110 Butterflies from cabinet drawers 3, 11 and 1. Brimstone male and female, Holly Blue males upper side and underside and female, Large White butterflies upper side and underside.