What is a Cephalopod?

Let’s talk about cephalopods! What’s a cephalopod? Well, it’s pronounced “seff-ah-low-pod” and it means “head feet” in Greek. Cephalopoda is a class of invertebrate animals (without a backbone) that includes animals like the octopus, the squid, the cuttlefish and the nautilus. The Greek name refers to the body shape of these creatures, which mainly seems composed of a large head (called a mantle) with numerous “feet”, which are commonly called tentacles but are more accurately referred to as “arms”.

There are about 800 living species of cephalopods. Most are mostly soft-bodied, with eight arms that feature rows of suction cups. Squid and cuttlefish also have two additional extra long tentacles that help them grasp prey. Nautiluses, the most primitive living cephalopods, are the only existing type that feature a hard shell, though extinct cephalopods were often shelled, and lost this trait over time.

 

Escape Artists & Masters of Disguise

Cephalopods are remarkable creatures. For example, octopuses are masters of camouflage, able to blend in by altering not just the color of their skin, but also the texture. They can also squeeze into some amazingly small places due to their entire body being composed of soft pieces, except for their small parrot-like beak. An octopus that weighs over 100 pounds can fit its body through an opening the size of a quarter! If these methods of escape and avoidance don’t work, octopuses and squids and shoot jets of ink to confuse predators, and even if an octopus loses an arm, it can regrow it back.

 

How Smart are Cephalopods?

Cephalopods are also very intelligent. Scientists have shown that octopuses can navigate their way through mazes, and have proven to be clever escape artists in captivity, often finding creative ways to leave the confines of their tanks. In the wild, octopuses have been shown to use tools, carrying around shells and coconuts to create protective shelters and hide themselves from both predators and prey.  They have been shown to exhibit learning behavior that demonstrates both long term and short term memory.

 

Some squids, such as the Caribbean reef squid, can communicate with one another by changing their skin color and patterns. But that’s not all that makes Caribbean reef squids amazing – they can also fly! Well…not exactly, but they are known as “flying squids” due to their ability to shoot themselves out of the water over six feet high, across distances of over 30 feet!

 

How Big do Cephalopods Get?

Reef squids are quite small, and as their name implies are often found on tropical reefs. As you get into the colder – and deeper – waters, cephalopod sizes tend to increase. The largest octopus is the giant Pacific octopus, which can weigh over 150 lbs. and reach an arm span of over 20 feet, though unconfirmed reports of much larger examples exist. The largest cephalopods are the colossal and giant squids, which can reach up to 46 and 43 feet in length, respectively, and may weigh between 500 and 1,000 pounds! These squids are both found in the deep oceans, between 1,000 and 3,000 feet below the surface, where they are preyed upon by sperm whales.

How Long Have Cephalopods Been Around?

Though some claim that cephalopods are so strange and extraordinary that they must be alien life forms from outer space, cephalopods have been around for a very long time right here on Earth. They first appeared in the fossil record almost 500 million years ago, in the Late Cambrian Period. Unlike most of today’s cephalopods, earlier examples had hard shells like snails. Many were spiral or cone shaped, but the shell style could vary wildly – one ancient cephalopod even had a shell shaped like a paper clip! 

Some of the most commonly seen cephalopods in the fossil record are called ammonites. These ancient cephalopods had shells resembling ram’s horns, which is actually where their name comes from: the  ancient Egyptian god Ammon is often shown wearing ram’s horns. Although these shelled creatures bear a resemblance to modern nautiluses, they’re actually more closely related to the soft-bodied squids and octopuses.

 

The Future of Cephalopods

Cephalopods face many threats today. Octopus, squids and cuttlefish are common food items throughout the world, and some species are seeing population declines that may relate to overfishing. Nautilus shells are also collected and sold for jewelry.

The largest potential issue that could negatively affect these creatures, however, is climate change. Ocean acidification occurs when the ocean absorbs carbon dioxide which lowers pH levels and makes the ocean more acidic. This negatively affects animal populations that cephalopods depend on for prey.

Warming oceans can also contribute to explosive growth of algae and plankton, which can limit the oxygen in an area and create “dead zones”. Octopuses that get stuck in these dead zones can suffocate, and those that move to shallower, more oxygen rich waters can become trapped.

Without taking steps to reduce climate change, we may lose these amazing, intelligent creatures forever!