Way back in December 2009, whilst diving at Balcony in Rooi Els, I came across what I thought was a juvenile squid. It was transparent, about 8cm long, had a small mouth and some little tentacles between its eyes.
We were in about 3m of water, in a protected gully and the SE wind had been blowing strongly for over a week. As we were with students, I couldn’t hang around for long, but it fascinated me by the way it would dance about avoiding my attempts to photograph it.
Not certain what it actually was, I sent my photo off to the team at SURG who came back to tell me it was a glass squid.
The family consists of 13 genera, of which there are about 60 species, many of which are undescribed.
Glass Squid can be found in surface and mid-water depths of the open oceans around the world. As they grow larger, they tend to seek deeper waters. Chances are it got brought in by the upwelling caused by the SE winds that had been blowing.
The sun-light water and their transparency make a really great camouflage.
They are eaten by deep sea fish such as angler fish, goblin sharks and whales.
They range in size from 10cm to 3m.
The name glass squid comes from the fact that they are, well, transparent!
Many species can be bioluminescent and have light organs on the underside of their eyes, used to cancel their shadows, making them even more difficult to spot.
A fluid-filled chamber containing an ammonia solution is used to aid buoyancy.
Often, the only organ that is visible through the transparent tissues is a cigar-shaped digestive gland which is usually held in a vertical position to reduce a silhouette and a light organ is sometimes present on the lower tip to minimise its presence in the water.
I have only ever seen a glass squid once since then, and interestingly enough, at exactly the same spot in Rooi Els!
Thanks to Mark Norman for confirming that this is a glass squid.
Young, Richard E. and Katharina M. Mangold (1922-2003). 2008. Cranchiidae Prosch, 1847. Bathyscaphoid squids. Version 22 April 2008. http://tolweb.org/Cranchiidae/19411/2008.04.22 in The Tree of Life Web Project, http://tolweb.org/
Cephalopods, a world guide, M Norman, 2000