Cuttlefish

As fellow cephalopods, cuttlefish have many similar traits to octopuses: from adept colour-changing capabilities to ink-redible defences, let's delve into some fun information about them.

Image of a Cuttlefish https://paulinespiratesandprivateers.blogspot.com

Basic facts:

Lifespan: Usually 1-2 years

Where can I find these guys??: In the sea Typically, shallow waters of Indian, Pacific and Atlantic Oceans.

Colour: Commonly brown (I recommend looking at pictures of Flamboyant Cuttlefish if you want to see some awesome colours).

Size: dependent on the species. Common cuttlefish are around 60cm. An interesting fact is that very small male cuttlefish will display patterns and colours similar to females to trick opposing larger males into believing they are females so they don't attack. The small male will then sneak into the female social circle and mate with them whilst the larger male remains completely oblivious! 

More Facts:

Cuttlefish have an internal shell (like cirrate octopuses) made of calcium carbonate. It helps maintain the shape of their mantle in differing depths of water and control buoyancy by altering gas and liquid volumes in the shell through pores - it is called a cuttlebone, and it's looong and flat, characterising their strange appearance. Cuttlebones can and have been used in jewellery casting, or in the making of other small metal accessories. The first recorded usage was in casting silver belt buckles in the 6th - 7th century where traces of cuttlebone were discovered in the burial grounds of Bopfingen (Baden-Württemberg, Germany). 

Another trait of the cuttlefish, like octopuses, is their eight arms. However, cuttlefish also have two hidden tentacles that can quickly snatch up prey in a cool surprise attack. Cuttlefish have a varied diet of crustaceans, fish and many small invertebrates (and sometimes, the littler cuttlefish!). They are aided by their W-shape pupils that allow for a large field of vision to help with hunting or spotting potential attackers. ln the case of being hunted, cuttlefish release brown or black ink from their ink sac through a siphon to confuse predators.

Cuttlefish ink has its uses in the arts with calligraphy and painting. An amazing fact is that its medicinal potential is also being investigated. Nanoparticles from cuttlefish ink have been suggested to inhibit cancerous tumor growth by cohering immunotherapy and photothermal therapy (read this research article to find out more - its a very interesting paper that encourages investigation into medicinal properties of other easily accessed natural materials).

REFERENCES

'Cuttlefish Bone Casting: Theory of Mold Making, Design Possibilities, Practical Casting Technique and Analysis' by Margaretha Held accessed 19/9/25, back.https://static1.squarespace.com/static/55f1c5d5e4b0e83b4ef3e659/t/66fc48b571232f26c4526d9d/1727809724639/2019-Held_Margaretha_Cuttlefish_Bone-Casting.pdf

'Cuttlefish' by National Geographic, accessed 19/9/25, https://www.nationalgeographic.com/animals/invertebrates/facts/cuttlefish

'On the architecture and function of cuttlefish bone' J Mater Sci 18, 2081–2086 (1983), by Birchall, J.D., Thomas, N.L. https://doi.org/10.1007/BF00555001

Date Published: 19th September 2025