In celebration of those marine animals with many arms, big brains, and no spine
Every year from the 8th to the 12th of October, International Cephalopod Awareness Days come around to teach the world about cephalopods. This event is all about celebrating and sharing how fascinating and incredible they are!
Cephalopods are a class of marine invertebrates that are easy to recognize by all their arms and tentacles. They are part of the Phylum Mollusca, which means they’re related to other animals with soft bodies and shells, like snails and clams. Unlike the other mollusks, though, cephalopods have large brains and are known for their intelligence. Cephalopods are also interesting because they have three hearts and blue blood. They have highly developed eyes, and they have an amazing ability to camouflage because their skin can quickly change color and texture (read more about that here!)
Photo by cephalopodcast via Flickr, Creative Commons License.
Read on for a day-by-day description of this holiday’s celebrations (source) and more fun facts. We hope you’re as ready to celebrate cephalopods as we are!
October 8 – Octopus Day, for all the eight-armed species
The octopus has eight arms (not tentacles). This is the cephalopod most famous its intelligence – from unscrewing jars, to using coconut shells as tools and escaping from aquarium tanks – stories abound about how octopuses outsmarted their surroundings, other animals, and even people.
Photo by Beckmannjan via Wikimedia Commons, Creative Commons License
October 9 – Nautilus Night, a time for all the lesser-known extant cephalopods
The chambered nautilus, unlike other modern cephalopods, still has an external shell. It has many chambers inside its shell, which hold gas. By changing the amount of gas inside, it can make itself sink or float. It spends most of its time in deep water but comes to shallower water at night to feed.
Photo by Klaus Stiefel via Flickr, Creative Commons License.
October 10 – Squid Day/Cuttlefish Day, or Squittleday, covering the tentacular species
The squid and cuttlefish have two tentacles in addition to their eight arms. Squids have bodies that are long and torpedo-shaped, and they may be the world’s fastest invertebrates. Their ancestors had shells, but squids now have only a pen – a stiff, feather-shaped structure that muscles attach to inside the mantle.
Photo by Klaus Stiefel via Flickr, Creative Commons License
Cuttlefish have also lost their external shells. Instead, they have a cuttlebone inside their mantles, a calcareous oval disc. It is porous and holds air, and the cuttlefish can use it to control buoyancy.
What’s it like to dive with the world’s largest cuttlefish? You can read here about cinematographer Howard Hall’s experience doing just that – or watch for yourself!
October 11 – Kraken Day, for all the fantastical cephalopods of myth, movies, literature and legend. Cthulhu fthagn!
Strange, enormous, and rarely seen, it’s no surprise that certain cephalopods inspired legends! Read more about the very real creature that was often mistaken for a sea monster here and enjoy the unexpected shout-out in this video (you can skip to around 0:30):
October 12 – Fossil Day (to coincide with National Fossil Day), for all the incredible suckers that have gone extinct but left an impression with us.
Cephalopods are an ancient group of animals that have existed in our oceans for millions of years. While there are about 800 known species alive right now, scientists have identified about 17,000 extinct species through the fossil record, including entire taxonomic groups that have gone extinct such as the subclass Ammonoidea.
Photo by Mike Beauregard via Flickr, Creative Commons License.