Specimen of the Week: Week 150
By Pia K Edqvist, on 25 August 2014
I did not really have a choice selecting the specimen of the week; this as a particular specimen was speaking to me in the corner of one of the display cases, I felt somewhat hypnotised. Firstly because the way it looks; it has an extraordinary appearance consisting of a lattice-like pattern in a somewhat geometric and architectural design, the specimen is very beautiful. Is it actually made of glass? Studying this specimen it has proven to have depth (it lives in the deep sea) but also breadth; its uses are many and its fascinating qualities are still investigated, this animal still raises more questions than provides answers.
This week Specimen of the Week is…
**Venus’ Flower Basket, Euplectella aspergillum**
1) Habitat and distribution
E. aspergillum is a deep sea sponge which is an animal without any internal organs. Sponges are filter feeders; creating a current to draw water in through their tissues and filter out any small particles of food. This particular sponge is found in a small area of the sea nearby the Philippine Islands. Similar species occur near Japan and in other parts of the western Pacific Ocean and the Indian Ocean. These sponges live at depths between 10 and 1000 meters (20-3,300 feet) occur at depths where the water is very cold (2-11o C or 32-52o F). They require a solid substrate such as rocks to attach to. The body structure of these animals is a thin-walled, cylindrical, vase-shaped tube with a large central atrium. The body is composed entirely of silica, actually microscopic needles of silica deposited in three making up the complex structure. (See detailed picture of structure).
2) Morphology and technology
The sponge extracts silicic acid from seawater and converts it into silica, then forms it into an elaborate skeleton of glass fibres. This is why this sponge and related species are commonly known as glass sponges. Because of this their structure is extremely strong and resistant to cracking, its structure is so clever that is has been adopted within the field of skyscraper design. The sponges are also of interest to fiber optics researchers which look at the 5–20cm long and thin glassy fibers that attach the sponge to the ocean floor, which are as thin as a human hair. The current manufacturing process for optical fibers requires high temperatures and produces a brittle fiber. A low-temperature process for creating and arranging such fibers, inspired by sponges, could offer more control over the optical properties of the fibers. To learn more about the research into the field of architectural design and fiber optics technology relating to the sponge; here is an amazing video. There are many people fascinated and amazed by this sponge among these people are David Attenborough; who included the sponge in a BBC program where he chose the ten creatures he would take on his ark and save from extinction.
3) A love story
Like the specimen in the photo we usually only see the ‘skeleton’ of these animals bleached and dried but in the living animal the skeleton is covered by a thin layer of cells. The specimen under investigation has previously been described as having a pair of Spongicola inside (only fragments can be seen inside today, (See picture). But what are Spongicola? They are two tiny shrimps that are commonly found living in symbiosis inside the sponge’s body cavity; always a male and a female. They swim in as larvae and then get trapped inside the sponge’s mesh-like tissues as they grow to adults. They are perfectly happy (from what we know!) as they feed off the filtered food debris left by the sponge. Any young can escape from the sponge as they are small enough to swim through the mesh of the sponge’s tissue and can move to find their own sponge as a home. The shrimps life inside this sponge is seen as a ‘good luck charm’ and therefore a sponge is given in some Asian countries, to couples getting married. In Japan they symbolise the idea of eternal life together, which is pretty understandable seeing these shrimps inside this sponge is literally ‘locked up forever’. Who would have though a sponge at the bottom of the deep dark sea could be so fascinating…
Pia Edqvist is the Curatorial Assistant at the Petrie Museum of Egyptian Archaeology, temporarily assigned to cover equivalent post at the Grant Museum of Zoology.