Creature Feature: Octo-what?

Ah yes, the Octopus, one of my all time favorite underwater critters. Their intelligence and multitude of fun facts have always intrigued me, but for years one question has plagued me dive in and dive out. Upon choosing our eight armed friends as the topic of this article, I determined it was high time I got to the bottom of the mystery. So I grabbed my prescription dive mask and jumped into the Batfishmobile to figure out this pressing question:

"Are three of these critters known as Octopuses, Octopi, Octopeese or what?"

(I’d like to take this opportunity to add an addendum to my last article on jellies. A group of our gelatinous friends is more properly referred to as a "fluther." Who would’ve thought?!)

So after hours of Googling, I determined that "Octopods" was the proper term for more than one Octopus. However, Octopodes and Octopuses are as well, and so is Octopi, a word that is so often improperly used it has become correct scientific jargon. So, I’ll try to make use of each one and all schools of thought will be mollified.

Octopods are recognized under the phylum Mollusca, which includes snails, nudibranchs, clams, oysters, mussels, as well as a few others. They are further classified under the class Cephalopoda. The word Cephalopoda is derived from the Greek words, "ceph," which means head, and "pod," which means foot. The class Cephalopoda includes squid, cuttlefish, nautilus, as well as Octopods; animals that all have their "heads" attached to their "feet." These nomenclaturists were onto something. However, we marine biology nerds prefer to call the "head" the mantle and the "feet" the arms. And while we’re on it, the word Octopus is derived from the Greek language as well, "okto" being the number 8 and "pous" meaning feet. I hope I’m not offending your knowledge of sea life by mentioning that all Octopods have eight arms.

The more than 250 known species of Octopi occur in all parts of the world’s oceans. The largest and smallest known species of Octopuses are both found off the West Coast of the United States. The largest known species is the North Pacific Octopus that grows to a maximum size of over 30 feet and an impressive weight of 100 pounds! The smallest known species is the Californian Octopus, which only reaches about one inch in length.

Notoriously shy and mysterious, certainly there are more species of Octopods that have eluded scientist’s probing eyes. Recently a deep water Octopus was discovered, and affectionately dubbed "Dumbo." The scientific name is Grimpoteuthis, but the common name that describes the ear-like swimming flaps seems more fitting. Recently while working offshore during an oceanographic survey, we pulled one of our seafloor instruments on deck, only to discover that we had a stowaway. Turns out that this eight-legged hitchhiker responds to the name Dumbo! He was a bit shaken from the journey to the surface from hundreds of meters down, but was still alive as we slid him back into his aquatic domain.

After great struggles or desperate vanishing acts, Octopi are often noticeably slow and lethargic. This is due to the oxygen-carrying component of their blood, hemocyanin. Hemocyanin is copper-based and not to be confused with the more efficient iron-based hemoglobin that we have in our blood. So while copper-based blood is sufficient for short bursts of speed and activity, prolonged exertion quickly results in an oxygen-deprived Octopus.

Octopuses have been blessed by Mother Nature with the most complex brain of all invertebrates. This brainpower is exhibited in their ability to learn through trial and error. Scientists have proven that these animals have short-term as well as long-term memories, similar to those of vertebrates. Makes you think twice about double-crossing an octopus now doesn’t it?

This brings us to a very important point; never underestimate the ability of an Octopus to escape an aquarium! If he wants out, he will probably find a way whether by lifting the lid or squeezing through a water filter. And don’t tempt him by placing his favorite snacky-poo of all time in the tank next door because the neighboring graduate student will be very displeased when he comes in to count his crabs in the morning. I’m sure you may have heard stories about these escape artists; just about every public aquarium has one about these Houdinis of the aquatic world. Often times it was only the watchful eye of a video camera that cracked the case of the missing animals.

The ability to squeeze into tight spots is not only useful in escaping aquarists, but in the natural world as well. They can they fit into tight spots to avoid predators and also while hunting small invertebrates that escape into rocky crevices. The only limitation to the space that an Octopod can fit into is the size of their eyeballs. The remainder of their body can be squished and squeezed with the exception of their hard beaks, which are smaller in comparison to their eyes.

In a weird alien sort of way, the Octopus mating ritual is the most graceful display I’ve been privy to witness. Somewhere between the alien puppets from Sesame Street and a psychedelic computer display, these fascinating creatures dance a mating ritual that has been performed for centuries. Similar to the mating ritual of squid, a male Octopus must insert a packet of sperm into the body of a female when she is ready to mate. Two months after fertilization she lines their interior of her lair with the strands of eggs. There she will tend to the eggs until they hatch and swim away; at which point she will die.

In addition to the well-known ability of Octopuses to jettison ink when pursued by predators, they have the ability to rapidly change the color and patterns on their bodies. This is accomplished through specialized cells known as chromatophores and melanophores. Each chromatophore contains pigment sacks of red, orange, and yellow while melanophores contain the colors black and brown. When the sacs are dilated, the pigment spreads out and the color is displayed. There are other color cells known as iridocytes that differentially reflect light. These cells produce the iridescent color of the Blue-Ringed Octopus as well as the eye-spots of some other Octopus species. Octopi also have the ability to create texture on their skin. In a flash, they are able to fade into the seafloor, giving the illusion that they are part of the rocky substrate. I’ll tell ya, somedays I wish I could look like an office chair.

The full scope of these fascinating creatures continues to elude marine biologists. Someday we may unlock all of their secrets, but presently I am content to observe all the mysterious behaviors of these eight-armed wonders each time I am blessed with their presence on a dive.