By Mark Carnall, on 26 November 2013
Back in October, I introduced this series (here’s a link to the opening post) about the specimens you’re near guaranteed to see in every natural history museum. We’ll take each specimen in turn and have a look at why they’re a usual suspect for display in a natural history museum.
The first specimen we’re going to take a look at is the Japanese spider crab. Japanese spider crabs are just one species, Macrocheira kaempferi. Confusingly, there is also a group of crabs, the family Majidae, called spider crabs which doesn’t include the most famous spider crab of them all. Japanese spider crabs are mostly found in coastal waters of southern Japan and have been recorded in waters as deep as 600 m so why do we find them in museums all over the world?
One rather Freudian reason I’d suggest is because they are big. Record-breakingly big in fact, with the largest leg span of any arthropod up to 3.8m from claw to claw. If you’ve ever seen one in a museum they are very striking objects and being big is an easy way to get the attention of human visitors. We’re very visual creatures and in the evolutionary past this has served us well but unfortunately, in the 21st Century museum it means that big invertebrates (animals without backbones) enthuse and engage visitors more than drawers and drawers of insects or bottles of corals ever do. It’s for this reason we see other large invertebrates as staple museum display specimens; giant clams, giant squid (models mostly) and extinct giants such as the giant dragonfly Meganeura and those giant Eurypterid sea scorpions*.
Crustaceans as a group are incredibly diverse with over 60,000 species but most of us would be hard pressed to name more than a dozen and most of those will probably be ones that we eat. It’s something I’ve written about before in a blog post about Hollywood animals. Most people get through their lives absolutely perfectly without knowing every single species of crab but when there’s a species like the Japanese spider crab that shakes our perceptions of what crabs ‘should be’ (i.e. small sideways walking, pincery things) we tend to remember it. It may be for this reason that Japanese spider crabs are so commonly displayed because impressive specimens of these crabs cause us to reflect on the order of things and question our superiority. They have a wow factor (we do use this terminology in museums to describe such specimens) to visually communicate to visitors through the glass more than we could ever express on a label or in a text book.
Another reason why they may be a popular exhibit in museums is because they are a bit scary. The clue is in the name. Not only is it a giant invertebrate but the long spindly legs relative to the ‘body’ size makes it resemble a spider (hence the name). It’s for the same reason that we find all manner of long legged beasties in science fiction, literature and art from triffids through to Louise Bourgeois’s Maman sculptures, Starship Troopers’ arthropod cast of critters through to Half Life 2‘s striders. There’s something about having legs much bigger than your body that sets off biological alarm bells and if you plant yourself near a specimen in a gallery you’ll hear exclamations ranging from “Wow” to “Eeeeergh” all day long.
For those of you who know it, the Grant Museum, in yet another tentative accolade for the Museum, has perhaps the saddest Japanese spider crab specimen on display. The specimen is squashed in a box way too small for it, it’s been bleached completely white from being on display over the years and one of the legs is currently sitting at the bottom of the box. Manchester Museum has one peering out onto the street, a great way to pull the visitors in. From memory there’s a specimen in the Natural History Museum at Tring, a lovely specimen in the Museo di Storia Naturale di Venezia and I think that one of the original specimens used to first describe this species in 1836 is on display in Naturalis in the Netherlands.
A very practical reason for Japanese spider crabs finding themselves on display is because when the exoskeleton is articulated and mounted they take up a huge amount of space, are very unwieldy and extremely fragile. It’s easier to have the specimens out on display wowing visitors than taking up all the space in the store.
So there’s our first natural history bingo specimen. Impressively large for us humans, who weigh up the importance of things based on how they measure up against us. On top of that they’re scary and a bit alien looking. These are some of the reasons why we tend to find Japanese spider crabs on display in museums. If you have any more suggestions or if you have a favourite Japanese spider crab you’d like to shout about drop us a line in the comments.
Mark Carnall is the Curator of the Grant Museum of Zoology
* The alternative is to make some giants of your own like the large animatronic spider and scorpion in the Natural History Museum London’s Creepy Crawly gallery, but if you go down this path prepare yourself for the inevitable day when advances in robotics make you look dated.