Halloween special: Dracula, false widow spiders and cave dwellers at the NHM

By Ben Miller | 31 October 2013

Every week, the Natural History Museum’s Diptera lab sets up a Malaise trap in a tent-like structure within the museum grounds.

A photo of a strange specimen of intricate yellow dragonfly against a black backdrop
The spirit of Count Dracula lives on in a Halloween bug discovered by volunteer scientists© Natural History Museum
The specimens which visit are usually flies. But a leafhopper, discovered by biology graduate Cagla Stevenson, has been dubbed the Dracula bug.

"We were surprised to see a spooky little face staring back at us when we looked through our samples,” says Dr Erica McAllister, the resident Curator of Diptera.

“This bug is immature. Its pattern would probably darken to blend in as it matures.

“This is quite unusual. Leafhopper markings vary a lot but I’ve never seen markings in this shape. It's all the more appropriate with Halloween coming up.

“The fact this looks like a vampire’s face really took us by surprise.”

This bug feeds on the sap of plants rather than human blood, meaning it negates the sort of public fears reserved for the increasingly common false widow spiders in Britain.

A photo of a dark brown and black spider crawling across a section of grey rock
The false widow spider has caused panic in some areas© Brenda Avery
Appearing more visibly in autumn – when the larger examples reach their maximum leg length of 25 millimetres, and males tend to go on mating sprees – false widows are one of the few domestic spiders capable of biting humans.

“I am happy living alongside this spider with my wife, three children, cat, dog and chickens,’ says Stuart Hine, the manager of the museum’s Identification and Advisory Service, reassuring visitors by pronouncing his family “aware but not worried.”

“In no way can this species be considered ‘deadly’ and to report so would be a gross exaggeration.

“Media reports of severe symptoms are rarely backed up with identification of the spider that caused the bite, and may not be due to a spider at all.

“In truth, these extraordinary symptoms are more likely to be caused by other medical complications, such as bacterial infection of a wound that may or may not be attributable to a spider bite.

“Even in homes with several resident false widow spiders, you are statistically far more likely to be stung by a wasp or bitten by a dog.”

Although the false widow is said to become aggressive only when prodded, squashed or trapped in clothing, the Service still receives around ten reports of spider bites each year.

A lace web spider, which is also prominent at this time of year and is often confused with the false widow, may bite. But identifiers say any attack will cause “little pain or lasting symptoms” – unlike the remipede, a cavernous creature which, according to experts studying its glands, is the world’s first venomous crustacean.

An image of a scientific diagram showing a shell-like crustacean figure with drawings
This illustration of the venomous remipede was drawn in 1858© Jan Nieszkowski
“This venom is clearly a great adaptation for these blind cave-dwellers that live in nutrient-poor underwater caves,” points out Museum zoologist Dr Ronald Jenner, discussing the remipede’s “highly toxic”, enzyme-filled neurotoxins, bearing similarities to those carried by fatal spiders.

“While they can be as varied as tiny waterfleas, krill, crabs and barnacles, not one of the approximately 70,000 described species of crustaceans was known, until now, to be venomous.”

Remipedes, who live in underwater caves in the Caribbean, Canary Islands and Western Australia, liquefy their targets before sucking a liquid meal from their exoskeletons.

Jenner says strength or venomousness are the key attributes of species which devour prey their own size.

One of the only other crustaceans regarded as a predator is the mantis shrimp, which bludgeons its victims to death, although a fish parasite capable of piercing the skin and feeding on the blood flow from the resultant haemorrhaging is a certain candidate.

Those with frayed nerves might envy the oldest and most intact nervous system, identified by museum palaeontologists in a 520-million-year-old fossil featuring a brain, nervous tissue to do with the eyes and a nerve cord running through eight of 11 segments in its trunk.

An image of a nervous system in a fossil with sections lit up in purple and green
The head and anterior two trunk segments of the Cambrian “great appendage” arthropod. The nervous system (white) is identified by the overlapping signal of X-ray computed tomography (green) and tissues enriched in iron (magenta)© Natural History Museum
The Chinese fossil is part of a group of early animals known as great appendage arthropods, named after the large, claw-like limbs attached to their heads and related to insects, spiders, lobsters and millipedes.

“This is the first time that fossilised neuroanatomy has been used to sort out how these animals are related,” explains Dr Greg Edgecombe, a museum palaeontologist who has worked with an international team of scientists on the research.

“It supports the idea that great appendage arthropods are the same group as horseshoe crabs, scorpions and spiders – called the chelicerates.

“We had suspected from their external appearance that the great appendage arthropod was part of that group, and by identifying the nervous system we now have greater evidence to show that they are.”

Anthropods’ nervous systems had mystified researchers until now.

“This research helps to open up further possibilities in the relatively new field that we call neuropalaeontology,” says Dr Xiaoya Ma, a fellow palaeontologist, calling the level of detail of the revelations “very exciting”.

“It also shows how important museum specimens are in answering some of the big questions about evolution.”

What do you think? Leave a comment below.

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