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Cuttlefish: Masters of Disguise

Hide and seek is a childhood game that most children enjoy but cuttlefish take it to the extremes. Not only can cuttlefish use their abilities to hide from predators, they can also catch prey and communicate with other cuttlefish by changing their appearance.

In this article, I will explore how cuttlefish not only survive but thrive.

How do cuttlefish transform?

The Cuttlebone

Cuttlefish are able to change their shape and texture to look like a variety of sea plants, animals, corals and even sand. They are all able to do this due to a special internal bone called the cuttlebone. The cuttlebone is composed of calcium carbonate and also plays a role in the buoyancy of the cuttlefish. There are tiny chambers that fill with different amounts of gas depending on how high or low the cuttlefish wants to float. If the cuttlefish wants to float higher in the ocean, it simply fills the chambers with gases. If the cuttlefish wants to sink, it empties the chambers.

Skin Structures

Even though cuttlefish have a natural colouration of a mottled brown or black, they can change colours in a split second. There are three types of structures in their skin that allow them to change from a bright pink colour to a sandy brown at any time. These three structures are called chromatophores, leucophores, and iridophores. They are actually small cells within the skin that are filled with many colours of ink. Cuttlefish can expand and contract these cells to communicate with other cuttlefish and to mimic their surroundings.

Where do cuttlefish live?

Cuttlefish are found primarily in the Mediterranean and North Baltic Seas. They stay on the edge of the continental shelf, which is about 200 metres beneath the ocean surface, or mainly between high and low tide lines. Occasionally, cuttlefish are found nearly 600 metres beneath the surface. Incredibly, some populations of cuttlefish have even been found as far south as Africa.

It is clear that cuttlefish require vast stretches of water to live and so they are not the simplest of animals to domesticate. However, cuttlefish make interesting pets. Most adult cuttlefish need a 200 gallon tank of water and must be fed live food, making them difficult to keep as pets. Despite this, some people do keep cuttlefish as pets and many are bred into captivity.

What is the cuttlefish diet?

Cuttlefish eat a variety of small fish and crustaceans. Baby cuttlefish normally eat shrimp and small crabs with the occasional small fish. Cuttlefish have a unique way of hunting down their prey. They camouflage themselves and when the prey comes near, the cuttlefish shoots out its tentacles and pulls the prey to its beak so that it can paralyse the victim with its poison and eat it.

Cuttlefish also swim near the ocean floor where shrimp and crab are hiding under the sand and shoot out a jet of water. This jet uncovers the prey and makes it easier for the cuttlefish to grab its food. Furthermore, cuttlefish have small suckers all over the pads of their tentacles that help them hold on to the prey during this process.

Predators…yet prey as well

Although cuttlefish are great hunters, they are also prey to animals such as sharks, monkfish and swordfish. Cuttlefish hide from these predators using their special camouflage techniques. Cuttlefish also shoot out ink from their ink sacs to confuse predators and hopefully escape. The ink was originally used by humans for writing but today most people use a synthetic ink produced in factories. Cuttlefish are still considered as human food and they are taken from the Mediterranean, East Asia, the English Channel and elsewhere. Cuttlefish is considered a delicacy and is often served like calamari.

Reproduction

Cuttlefish mate only once in their lifetime but when they do reproduce, it falls during the months of March and June. Males transfer sperm to females through a tentacle used only for mating. During the mating season, male cuttlefish change their body colours to successfully attract a female. Some crafty male cuttlefish have even been known to make themselves look like a female to trick the dominant males so that they can steal their mates. Female cuttlefish will mate with several males and store the sperm until they decide which ones they want to use. This allows females to choose who the father of the offspring will be (this may be an adaptation to select for greater intelligence in offspring). The female cuttlefish lays around two hundred small eggs and dies soon afterwards. A cuttlefish’s eggs are coloured with ink to blend in with the surrounding substrate so that they will not be eaten by other predators.

Unlike their squid and octopus cousins, baby cuttlefish are already highly developed and independent immediately after hatching. Instinctively, they begin to track down small crustaceans and fish. They grow quickly and can size up to a metre in length. Typically, a cuttlefish will live for 18 to 23 months.

Cuttlefish are not yet a threatened species but because of their short lifespan and the fact that they only reproduce once in their lifetime, there are obvious threats of overfishing. Fishermen in Australia catch up to 71 tons of cuttlefish annually for human consumption and for bait. There are no current management restrictions in place to limit the number of cuttlefish that can be taken from the seas but there is pressure to add the giant cuttlefish to the endangered species list.

Conclusion

With the ability to change their appearance for a variety of reasons, cuttlefish truly are masters of disguise. Despite not being on the endangered species list, it is important that we keep as many animals as possible off the list by preserving habitats so that future generations can appreciate the variety of life of our planet. It is clear that cuttlefish contribute so well to our beautifully diverse planet.

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