15th October: Sponges!

Did you know that some creatures can make their skeletons out of glass?

It never fails to amaze me!  My name is Kate Hendry, and I’m a research scientist at the University of Bristol who specialises in understanding the chemistry of these amazing and diverse organisms.  Diatoms, a type of single-celled algae that grows in sunlit surface waters, make ornate shells out of silica (or opal). Sponges are simple animals that live on the seafloor, and live by filtering particles and taking dissolved nutrients out of seawater. They also make a skeleton out of little “spicules” that can be needle-shaped, star-shaped, hooked and barbed.

All of these organisms need dissolved silicon to grow. I study the chemistry of the opal that sponges and diatoms produce, in order to understand more about how they grow. If we know what processes influence the chemistry of these organisms, we can then use their fossilised skeletons – that we find in deep-sea sediment cores – to figure out more about ocean chemistry in the past and how it relates to carbon cycling, ocean circulation and climatic change.

On this cruise, I have a few roles. Firstly, I’m here – obviously – to collect samples of opal!  I’ll be collecting deep-sea sponges from the seafloor, thanks to the ROV crew, and diatoms from the seawater. I’ll also be able to take samples from the sediment cores for fossilised diatom shells and sponge spicules.

Secondly, as I’ve been to sea a few times before to sample seawater, I’m here to help manage the water collection and archiving. We use large bottles, attached to a frame with various sensors (so we can measure the temperature and saltiness of the water), to collect water from different depths. The water is then brought up to the surface, where it can be measured for its oxygen content, or stored for other tests back in the UK.

Thirdly, I’m always keen to help out with outreach to the public, making podcasts (which can be seen on our Youtube channel!) of videos and interviews, and helping out with the blog. Eventually I’ll also be making a longer edited film, when I’m back on dry land! I hope very much that you enjoy the podcasts and blog, and sign up to our Twitter feed and Facebook page!

Blog written by: Kate Hendry