In a new blog series, our Conservation Trainee Abi David explores some of the amazing creatures that call seagrass meadows their home. Cuttlefish are molluscs and join squid and octopuses in the Cephalopod family. Predominantly found in temperate and tropical areas, 120 species can be found around the world. Cuttlefish
In a new blog series, our Conservation Trainee Abi David explores some of the amazing creatures that call seagrass meadows their home. Cuttlefish are molluscs and join squid and octopuses in the Cephalopod family. Predominantly found in temperate and tropical areas, 120 species can be found around the world. Cuttlefish have an internal shell, known as the cuttlebone, which helps with buoyancy. By changing the gas to liquid ration, they can determine how much they float. Their diet generally consists of small molluscs, crabs, shrimp, small fish, octopuses and worms. To catch their prey, they use suckers attached to their two tentacles, which shoot out and grab unsuspecting victims. The flamboyant cuttlefish (Metasepia pfefferi) even uses venom to subdue its prey. To escape predators themselves, they can propel themselves forwards or backwards by expelling a powerful jet of water from their mantle cavity (main body). Cuttlefish in seagrass, Cornwall, UK. Credit Shannon Moran Ocean Image Bank Cuttlefish. Credit François Baelen Ocean Image Bank Like other cephalopods, cuttlefish have quite sophisticated eyes. They have two spots of highly concentrated sensor cells on their retinas – meaning they can look both forwards and backwards at the same time. This ability is aided by their W- shaped pupil, giving them a wide field of vision. It is thought cuttlefish eyes are fully developed before hatching, enabling them to begin observing their environment whilst still in the egg. Part of why I love cuttlefish so much is their ability to change colour using skin cells called chromatophores. They do this by expanding and contracting these cells to resemble colours and patterns found within their environment for camouflage and warning off predators. I could go on a lot more about this amazing ability, but this article by Gilmore, Crook, & Krans, gives a nice, detailed overview. So how do they utilise seagrass? Seagrass is an important habitat for cuttlefish. Many other creatures such as crabs, worms and snails call seagrass home, basically providing them with an all you can eat buffet. Additionally, like many other species, cuttlefish lay eggs on seagrass leaves as meadows provide a sheltered environment safe from currents and tides that may wash eggs away. Once these eggs have hatched, seagrass meadows provide a safe nursery site from predators. Cuttlefish eggs in seagrass, Dale, West Wales Why do we need cuttlefish? As with every other species on the planet, cuttlefish have their own unique purpose in the ecosystem. They are predators of a variety of species, meaning they help control populations – which is important to maintain a healthy ecosystem balance. They themselves are prey for commercial fish species such as Atlantic cod. In parts of the Mediterranean, Asia, and Europe, they provide an important part of human diets. Cuttlefish are, in my opinion, a hugely underrated species. Not only are they super cool with their colour changing abilities, but they are also an important part of many habitats and ecosystems across the globe. More information: Gilmore, R., Crook, R. & Krans, J. L. (2016) Cephalopod Camouflage: Cells and Organs of the Skin. Nature Education 9(2):1
