With greenish-blue blood, three hearts, a doughnut shaped brain and the ability to change color in a flash, the Cuttlefish is no doubt one of the brainiest and most bizarre animals in the ocean, almost alien as some would say.
Belonging to the Cephalopod “head-and-foot animal”, cuttlefish are not really fish at all but rather mollusks of the Sepiida class just like octopus, squids and the ancient nautilus. Similar in appearance to their squid relatives, they have one major distinguishing feature- their internal structure/shell called the cuttlebone, popularly seen at the bottom of bird cages and used as a calcium supplement. This unusual porous calcium based ‘cuttlebone’ not only forms the shape of their body, but also provides the cuttlefish with buoyancy control. Just as a BCD (Buoyancy Control Device or Buoyancy Compensator) is used in Scuba diving, the cuttlefish can regulate its buoyancy by changing the gas-to-liquid ratio in the chambered cuttlebone via a strand of tissue that passes through it. Cuttlefish also have eight arms and two tentacles between which its beak-like mouth can be seen as well as two fins that wrap around the mantle.
With a highly advanced nervous system and one of the largest brain-to-body size ratios of all invertebrates, Cuttlefish are amongst some of the most intelligent species and undisputed masters of disguise. These chameleons of the sea as they are sometimes referred to could become invisible by changing their coloration or patterns or switch on an electrifying light shows in an instant. Like the octopus, the cuttlefish’s skin has comprises of three layers of chromatophores (color pigment cells)—a bright yellow layer near the surface, under which is an orange-red layer and finally a dark base. In less than a second they can transform both in color and texture by making their individual cells expand or contract. These witty creatures often use this ability to change their shape and color to mimic their surroundings, intimidate their rivals or even hypnotize their prey. Experiments have shown that cuttlefish have swift learning curves and many scientists have the opinion that they can learn by observation. This keen observation is helped by the fact that they some of the most developed eyes in the animal kingdom, which bear a resemblance in construction to human eyes. Although they cannot see color, they can perceive the polarization of light, which enhances their perception of contrast.
Cuttlefish are mostly shallow-water animals although they are known to go to depths of about 600 meter (2,000 ft). They are almost never found in the waters around the American continents but are widely present in the waters of east and south Asia, western Europe, the Mediterranean, as well as all coasts of Africa and Australia. Cuttlefish prey on crabs, shrimp, fish and small mollusks as they are known to be bottom feeders.
For divers, spotting their first cuttlefish is often like love-at-first sight. At first they are hard to spot and appear like a blog hovering above coral tops, but the closer you get their incredible beauty and grace comes through. The rhythmic wafting of its frills, its pulsating skin and intelligent eyes with that almost curious stare is mesmerizing to say the least. But be warned that they are known for hypnotizing their prey by creating concentric circles of color that appear to flow towards the onlooker, so just incase, you might want appear like a non-threatening observer even though he’ll have an unblinking eye on you!
*Photo Credits: photos by richard ling, Simen S, RA_ul and Boogies with Fish on flickr
