There are many predators who enjoy eating octopuses, including cod, halibut, sea lions, harbor seals, sharks and dolphins. Even most tiny octopus babies, newly hatched from their populous egg clusters, succumb in the first hour of their lives to a variety of sea creatures looking for food.
A shy, solitary mollusk who is an expert at hiding, the octopus has some adaptations that enable it to elude predators very quickly. It belongs to a unique class of creatures called cephalopods, which are “head-footed animals,” with its appendages are attached directly to the head. The “head” of an octopus is actually a muscular sac which contains its organs, and underneath, at the point from where the octopus’s eight arms radiate, is the animal’s mouth, which has a hard beak.
The Octopus Jet-Propels to Safety
Protruding from the head is a hose-like “funnel.” Through this funnel the octopus can force water from its body that it has drawn in through gills. This muscle action results in jet-like propulsion; the octopus can move away quickly in any direction by aiming the funnel appropriately.
The eight arms on an octopus serve a variety of purposes, from feeling its environment, to snatching food, to maneuvering in the water, mating, and even tossing out leftover shells from a meal of abalone or crab. Suction cups on the tentacles have sensors that not only help with tactile function, but also tasting, and detecting chemical changes or changes in water currents that would indicate predators are nearby.
The Octopus Can Change Faster Than a Chameleon
An octopus’s first reaction when frightened is to turn white. Once it has jet propelled itself away from the predator, it will settle and change its color and texture to blend with its background. The octopus’s skin contains color cells called chromatophores. These enable the octopus to lighten or darken its skin, matching the patterns in its environment, such as a pebbly sea floor or coral bed. Even baby octopuses smaller than a thumbnail already have the ability to alter their coloring. Hiding in plain sight is a pretty simple way to fool a predator.
The Octopus’s Ink Blob Decoy
One defense mechanism the octopus uses to distract a predator before propelling itself to safety is to squirt an ink blob. Like other cephalopods, including squid, the octopus has an ink sac. In order to fool a predator for a few moments while it makes its getaway, the octopus will squirt a mixture of ink and mucous together with the water forced out of its funnel. The dark ink adheres to the mucous droplets, creating a temporary cloud in the water that is said to generally resemble the shape of the octopus, acting as a decoy.
Octopus Species With Unique Escape Tactics
There are over 150 species of octopuses. Some have traits unique to their species that help them stay safe. One example is the banded drop-arm octopus (Ameloctopus litoralis) in Australian waters. If a predator attacks one of its tentacles, the octopus can break off the arm and swim away. The predator doesn’t notice because the arm continues to wriggle while it is being eaten. The octopus will regrow a new tentacle in six to eight weeks.
The mimic octopus (Thaumoctopus mimicus), a type discovered in 1998 in Indonesia, is a long-armed species patterned with light and dark spots and stripes. It will shape itself to resemble the most dangerous enemy of the predator that is stalking it. It has been seen burying itself so that only two arms are visible, stretched out horizontally to resemble a sea snake, and coiling itself up into the shape of a stingray.
The blue ringed octopus (Hapalochlaena lunulata), the only species whose venom is known to kill man, has bright colors that are simply a warning for predators to keep away. This octopus will purposely change its coloring when it wants to blend into its surroundings while hunting for its own food in the shallow Pacific reefs and tidepools it inhabits. The glass octopus (Vitreledonella richardi) of the dark, deep sea is transparent, so predators cannot even see it. Another type, the southern keeled octopus (Octopus berrima) simply buries itself to hide from predators.
Whatever method an octopus uses to avoid becoming prey, it is clear that these creatures are intelligent, inventive, and possess amazing adaptations. The octopus as an “escape artist” and “phantom of the sea” are appropriate terms for this elusive sea creature who was once misunderstood as a hideous “devilfish.”
Sources:
- Cerullo, Mary M. The Octopus: Phantom of the Sea. New York: Cobblehill Books, 1997.
- Markle, Sandra. Octopuses. Minneapolis: Lerner Publications Company, 2007.
- Norman, Mark D. “Ameloctopus Norman 1992.” Banded Drop-arm Octopus. Version 01 January 1996. Tree of Life Web Project, <tolweb.org/Ameloctopus_litoralis/20230>
 |
