Mermaid’s purses and the importance of looking sideways
By Eleanor Morgan, on 4 February 2015
Among the Grant Museum’s collection of glass sponges, there are a few specimens that really demand attention. One is the Venus’ flower basket, Euplectella aspergillum, an intricate weave of spicules in the shape of a sealed cone. Its romantic name comes from the behaviour of a species of Spongicolidae shrimp who make their home inside the sponge’s glass cage, where they feed off creatures filtered through the sponge’s walls. Having entered the sponge at the larvae stage, the shrimps grow too big to ever leave and remained trapped inside for life. In parts of Japan, dried specimens of the Venus’ flower basket are given as a wedding present, with the two shrimp preserved inside.
The other show-stopping specimen is harder to see, as it sits in the dark in an out-of-reach cupboard: the glorious glass rope sponge, Hyalonema sieboldi. Formed of a bulbous top of interlocking spicules, this animal roots itself into the sea floor using a long twisting rope of glass, which resembles a bundle of optical glass fibres. The Museum’s specimen has been mounted within an unsteadily tall and thin glass jar, and visitors can only spot it up in the rafters using the binoculars provided. However, it is not alone. While it was alive, a cluster of zoanthids, colonizing creatures resembling brightly coloured miniature anemones, made their home on its ropey root. And it has one other attachment: a shark’s egg case, commonly known as a ‘mermaid’s purse’. Clearly, the glass rope sponge is an attractive settlement.
This is the not the only example of a glass rope sponge with a mermaid’s purse attached, there is another in the storage rooms of the Natural History Museum in London, and one in the Museum of Victoria in Melbourne with only the tendrils remaining, wound around the glass fibres. It seems possible, therefore, that the people who first collected and mounted these specimens wanted to retain and preserve the attachment between sponge and egg case that had formed in the deep seas. However, an account from the mid-nineteenth century suggests another possibility. John Edward Grey, keeper of zoology at the British Museum, writes in 1868 that a glass rope specimen received from Japan has been ‘artificially doctored’ by the addition of two shark egg cases. Was there perhaps a trend during this period for attaching mermaid’s purses to sponges? In other words, is this bond natural or artificial?
I’ve been thinking about the mermaid’s purses this month – in particular the complexity of defining forms and materials as natural or human-made, organic or inorganic. Even within a single specimen jar there may be a gathering of organisms, making it difficult to decide what name to put on the label. If the beginning of my residency was about looking closely at the sponge specimens, then I’m now trying to explore these complexities. My intention now is to begin look sideways, to look at the objects and ideas that wind themselves around the sponges. As I wrote in my last post, this includes the human perception of glass as a living material, or the current uses of glass sponges to inspire the creation of optical fibres. They are attachments which are both physical and symbolic – creating real and imagined forms and different ways of perceiving how we define ourselves and our surroundings. By looking sideways, I want to ask: what are these attachments, and how are they formed?
 J.E. Grey, “On a new free form of Hyalonema sieboldii, and its manner of growth,” Journal of Natural History (Series 4, Vol.2, Is.10, 1868, 264-276) 267.
Eleanor Morgan is Artist in Residence at the Grant Museum of Zoology, funded by the Leverhulme Trust.