Seagrass Species Spotlight: Cuttlefish

11 January 2022  /  By Esther Farrant

Esther Farrant

Esther Farrant

Esther Farrant, ReMEDIES Education Officer based at the Ocean Conservation Trust, introduces us to her favourite mollusc – the cuttlefish...

These funny creatures are a mainstay of the seagrass bed community and we can spot them all over our local seagrass beds here in the south west and all around the UK.

If you want to find out more about Cuttlefish and see some up close you can visit the National Marine Aquarium in Plymouth. ‘Squirt’ our adorable British common cuttlefish (Sepia officinalis) lives in our Plymouth Sound exhibit.

Squirt, cuttlefish at the NMA/Geffrey Back

Cuttlefish are molluscs (related to snails and clams). Along with squid, nautilus, and octopus, they make up the group called cephalopods, meaning ‘head foot’. All species in this group have tentacles attached right onto their head.  The brain of a cuttlefish is enormous compared to other invertebrates (animals without a backbone) which means that cuttlefish can learn and remember.  Our Biologists here at the Ocean Conservation Trust are training Squirt to respond to enrichment during his feeding time, using a varied diet. Sometimes Squirt remembers which foods are not his favourite and will often hold out for his gourmet river shrimp over a piece of sprat!

Despite being colour blind, cuttlefish have very good eyesight and can vary their colour, shape, and movement rapidly to communicate or to camouflage.  From birth, young cuttlefish can already display at least thirteen types of body pattern.  Male cuttles display vibrant colour variations during courtship.  The male guards the female until she lays a bundle of black grape-like eggs which are attached and anchored to seagrass or other structures.

Top 5 Facts

  • Cuttlefish can jet out clouds of ink when they feel threatened. This brownish ink was once used for writing and photo printing and gives us the colour name ‘sepia’ from the Latin name for molluscs.
  • The buoyancy organ of the cuttlefish (the ‘cuttlebone’) can be found washed up on beaches once the animal has died. People who own pet birds use these bones as enrichment for the birds to sharpen their beaks.
  • Cuttlefish feed by using their extendable tentacles to catch prey as it moves past. They also have a razor sharp beak (similar to a parrot’s beak) hidden behind its tentacles. It enables cuttlefish to feed on hard shelled animals such as crabs. The bite introduces a toxin to quickly immobilise any troublesome prey.
  • Cuttlefish can move by ‘jet propulsion’, which can be an effective escape mechanism. They make their body very streamlined then quickly squeeze water from a cavity in their body, through a funnel-like tube called a siphon which thrusts them backwards very fast.
  • The largest cuttlefish in the world is the Australian giant cuttlefish (Sepia apama). They can grow up to one metre long and weigh more than 10kg.