Category: What’s on the van

What’s on the van? – Trilobite

This week’s What’s on the van? comes from Dr David Legg, Post-doctoral Research Fellow in the Museum’s Earth Collections.

This particular trilobite specimen (Acaste inflata) was collected and named by John William Salter during the Ledbury Railway Tunnel cutting in 1864. Salter worked with many famous scientists during his career; he was an apprentice of the famous mineralogist James De Carle Sowerby, before becoming a curator for Adam Sedgwick at the Woodwardian Museum in Cambridge (now the Sedgwick museum), and in his later years he assisted Roderick Murchison on his work on Siluria. During this time, Salter developed an interest in the trilobites of Wales and was considered a world expert on this group.

Trilobites are a group of arthropods (the group that includes spiders, scorpions, crustaceans, insects, etc.) characterised by the possession of a hard exoskeleton composed of calcium carbonate. They are some of the first animals with hard parts found in the fossil record. The first trilobites appeared roughly synchronously on various continents around 520 million years ago, and went extinct during the largest mass extinction of all time at the end of the Permian (c. 251 million years ago), nearly 20 million years before the first dinosaurs appeared.

Acaste inflata belongs to a group of trilobites called the phacopids. The eyes of phacopid trilobites are unlike any others in the animal kingdom. The eye may consist of over 50 lenses, each separated from the next by a thick interlenticular cuticle. Because there are no modern animals with similar eyes it is unclear how they functioned to produce a clear visual image, however, the shape of each individual lens meant it was capable of focussing on objects of varied distance without the need for any additional focal mechanism (like the human lens which needs to change shape in order to see objects of different distances).

This picture is a bit strange because the trilobite is enrolled (curled up like a woodlouse) and the view is of the top of the head. We assume that this was a form of defence used by most trilobites.

What’s on the van? – Jervis Label

This week’s What’s on the van? comes from Monica Price, Head of Earth Collections.

A story to tell
Each of the millions of different objects in our Museum has a story to tell – what it is, where it is from, who collected it, when and why. All that information is collected together on the specimen’s label, and museum curators look after labels like this just as carefully as they do the specimens themselves.

Some of the labels in the Museum are very old, but the handwriting can be distinctive. Although this label does not say who wrote it, we can tell from the handwriting, the style of number, and the Italian locality, that it was written by an Englishman called William Jervis. He was a geologist who worked at the Museo Industriale Italiano (Italian Industry Museum) in Turin during the second half of the 19^th century.

William Jervis wrote books on the rocks and minerals of Italy that are important for ores, building materials and water supplies. He also put together sets of rocks samples to be sold to other museums and universities. He trimmed each one to a neat rectangular shape and gave it a number. On the label, he’d write the number, what the rock was, and exactly where it was collected. Some of his labels are very detailed indeed and show that his samples came from places no longer accessible today. The specimen accompanying this label is one of a set of Sardinian rocks. It comes from San Giovannni mine, near Iglesias, and shows the kind of grey limestone that was found close to the ‘lode’, the vein of lead and zinc ore minerals which was being worked by the miners.

Do you have a collection of geological specimens, or maybe shells, plants or insects? It is always a good idea to do what William Jervis did, put a number on each specimen (maybe using a little paper label), and then write all the information about it on a label. It’s also a good idea to keep that information all together in a book or on a computer so that if a label goes missing, the information is kept safe. Don’t forget to keep a back-up of your computer file though, just in case!

What’s on the van? – Silk Moth

This week’s What’s on the van? comes from Kotaro Fujiyoshi, a work experience student from Merchant Taylors’ school in Middlesex. He is currently on placement in the Museum’s Hope Entomological Collections.

This picture is of a silk moth called Rothschildia jorulla, which was described as a new species to science by the Museum’s first Professor of Entomology, John Obadiah Westwood (1805 –1893). It was collected in Cuautla, Morelos, Mexico in 1853.

Moths of this kind belong to a group called silk moths, or saturniids. There are over 2000 species of saturniids, one of them the world’s largest moth, Attacus atlas. This group of moths are widely exploited across many cultures as sources of silk. Some species of the group are very well known, for example the silk worm (Bombyx mori), used by Chinese textile manufacturers from at least 5000 years ago. This Rothschildia is no exception, as its silk has been used for producing textiles in Mexico.

Unlike their domesticated counterpart, the silkworm, this moth is very well adapted to a life in the wild. For example, its four translucent patches and two black eye-like spots on the wings can easily be mistaken for eyes. Birds looking for a meal would peck at these obvious vulnerabilities instead of the body, so that all the important organs and flight muscles of the moth are protected from a fatal blow.

Saturniids have reduced or completely dysfunctional proboscises (mouthparts) and do not feed. This means that they are very short-lived as adults, surviving for only about 2 to 3 weeks. They are able to survive these weeks without eating due to their energy stores: as caterpillars, they eat enough food to last them all the way from pupation to the end of their short few weeks as adults. After emergence, the males spend the majority of their remaining time fluttering about, looking for mates. Females emit sex pheromones, vital clues for the males, and the males smell their way to find their mates, using their comb-like antennae.

Saturniids are most diverse in the tropics and are often seen flying to house and street lights on relatively windless nights of warm seasons.