A lesson in deep sea biology

In our lab today, we got to have a look at some rare, interesting and extremely ugly specimens from the deep sea.

My favourites included Histioteuthis, a squid that lives in a depth range between 200-1000m. For this rather large range it has 2 different sized eyes- the small one takes in light from the shallower areas and the large one allows more light in in deeper areas, which I found out a couple of years ago is also why pirates used to wear eye patches (so they can see above and below deck!).

There are a couple of photos of the actual specimen we looked at below, but the photo above allows a much better comparison of the eyes, so you can see there is a massive difference in their size.

Another was a fish with bioluminescent organs (photophores) under its eyes that act as headlights. I would love the opportunity to study bioluminescence in the future, it's an extremely interesting subject. Many of these organisms features in the photographs I have posted live in the deep Pacific, namely the Mariana trench-the deepest place on Earth. Only two people have visited this depth before, one of them being director James Cameron- fewer people have been in the deepest part of the ocean than on the surface of the moon. Let that sink in a little, and you will understand why I love this part of marine biology.

Bioluminescence is used for a range of things, mainly though for attracting pray, warning predators to keep away, and blending in with their surroundings. An example of the latter is a fish that lives in waters just above its predators (the twilight zone). It has photophores on its belly that emit light of the same colour and brightness as the water above it, basically erasing its own silhouette against what little light reaches down.

Some prawns have bioluminescent vomit that they throw up all over their predators, to confuse and choke them, allowing them to escape.

I could go on for hours, honestly, and I will probably write another post on this when I work out how to add photos from my phone. I hope you have enjoyed reading this as much as I have enjoyed learning about it and writing it!

This specimen is older than me!

A lot of deep sea fish have long, thin teeth, which make it easier for them to catch and hold onto prey, because in the dark often if the prey escapes, it's gone for good.

This is one of several species of deep sea fish that grow light-producing organs (photophores) under their eyes to act as headlights. In most cases, they emit blue light as it travels furthest in the dark, but some predators emit red light that only they can see- red light is absorbed first and so many organisms cannot see it.

This specimen was one I encountered a couple of weeks ago when I was helping out the deep sea department with their cataloguing. It is the squid with one eye bigger than the other. It was so big I had to take two photos to show the difference in size.

The pictures below give you an idea of what the photophores look like when the organisms are alive:

The red prawn on the right is adapted to deep sea conditions in two ways:

1. Its body is red in colour. This is because its predators cannot see red, which makes it invisible to them.

2. It vomits bioluminescent goo in the face of its predator, which blinds, confuses and sometimes chokes it, meaning it can escape.

There are some organisms that have photophores for unknown reasons, and I think this may be a subject area I would like to continue my studies in.