Guest Post: Cuttlefish by Grant Stirton

cuttlefish

Cuttlefish photo by Grant Stirton

The Cuttlefish

There’s one cryptic reef dweller, whose superior intelligence, curiosity and charisma has always captured my heart. With over 120 species worldwide, the cuttlefish is both an adaptable and resourceful predator. They belong to the taxonomic class of Cephalopods and their morphology is closely related to octopus and squid. I’ve been fortunate enough to encounter them many times over the years as they are common throughout the tropical coral reefs of South East Asia.

Why Are They So Interesting?

Behind their curious looks lies a relatively large and well developed brain. Scientific analysis has shown that their cognitive abilities can approach that of a two-year human child, making them the most intelligent of all invertebrates. In my experience, many seem to revel in an encounter with divers, so long as they are approached slowly and in a non-threatening manner. I’ve even put out my hand and had a particularly interested individual swim over and sit down for a short visit. Often they will look directly at you, examining and investigating, until they satisfy their natural inquisitiveness.

One of their most unique adaptions relates to their eyes and how they see. Shaped like the letter W, each eye has two pupils, allowing them to see forward and backwards at the same time. And although they are colour blind, they can detect the polarization of light, which significantly enhances their perception of contrast and ability to spot well-camouflaged prey.

Using a combination of specialized skin cells and pigment, they can also instantaneous change colour to match their surroundings, as a means of camouflage, to communicate or to ward off predators. In one study, biologists were able to train them to produce shapes on their backs as a form of communication when they desired food. Normally, if they feel threatened or are being aggressive, they will change colour to a dark reddish or brown. As you can see from the picture, our little friend was quite calm and happy, even though I was less than twelve inches away with a big camera. He was intent on having a very good look at his reflection in my lens and completely ignored me.

Although they are a mainly a predator of crabs and small fish, they are also prey for larger marine animals including fish, sharks and eels. As a means to defend themselves and escape an attack, they possess, as do octopus and squid, the ability to shoot out a trail of ink that creates a pseudo smoke-screen. Interestingly for photographers, many old sepia-toned prints were made using their ink. Fortunately today, this traditional ink has been replaced with less environmentally destructive synthetic varieties.

All this intelligence, adaption and cleverness requires a solid engine. As a result, the cuttlefish has three hearts in order to ensure orderly circulation. This is a necessity as they do not have the iron containing protein hemoglobin in their blood that vertebrates do, but rather hemocyanin, which is a copper containing protein that is less efficient in the transport of oxygen.

The cuttlefish also uses a form of jet propulsion to move through the water column, allowing them to swim both forwards and backwards effortlessly. An internal structure called the cuttlebone, which is porous and made of aragonite, allows them maintain perfect neutral buoyancy at depth via pumping gas into the structure. Even the United States military has borrowed from this concept and adapted a similar design for maintaining the buoyancy of their nuclear submarines.

If you do come across one of these amazing creatures while diving, here are a few suggestions that will help ensure a memorable, safe and unique photographic opportunity:

1. Always approach them slowly and calmly. A very slow approach from below or at eye level is best, as this is much less threatening than a big, loud diver dropping right in on top of them.

2. I always make sure to leave them an easy way to escape, so that they don’t feel cornered and decide to retreat. This also ensures I don’t end up being sprayed in the face with foul tasting ink.

3. Photographically, they make great subjects, however any erratic movement is likely to scare them. It’s best to back away slightly and ensure your camera settings, composition and frame before slowly getting into the right position for a good shot. It’s much better to get one good shot than a series of mediocre ones. I haven’t found flash to be much of an issue in frightening them, however, I do try to keep it on the lowest power setting possible given the light and conditions. Blinding an animal with a powerful flash is not only poor practice, but also lessens your chances for a follow up shot.

The accompanying photo was taken on the reef slope next to the USS Liberty Wreck located in Bali, Indonesia. We came across this cuttlefish at the end of our dive as we made our way up the shallow reef slope back to shore. This individual was so curious that we ended up spending almost a full ten minutes with each other. This allowed me the chance to get very close with my macro lens and take a memorable picture.

Our oceans are full amazing creatures and for many we are only beginning to understand their lifestyles and importance in the overall eco-system. The cuttlefish is a perfect example of an animal full of personality, but that has also provided us with a wealth of knowledge about the delicate balance of our marine environments.
[100mm macro lens, 1/100 sec @ f/4.0, ISO 200]

Grant Stirton

Grant Stirton

Grant Stirton is a passionate Canadian photographer, writer and avid adventurer who specializes in marine environments, culture and travel. He can be reached at www.grantstirton.com, twitter @grantstirton, Facebook www.facebook.com/LuumbaTribe .

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