One of the most covert hunters on the ocean floor may not be one that you see right away. Having one of the best means of camouflage, the octopus crawls, floats and propels its way through the reef, and only the sharpest of eyes can catch a glimpse of it.
The octopus, or he'e, is a cephalopod and is related to the squid, cuttlefish and nautilus. The name cephalopod means "head-footed" and is characterized by symmetrical bodies, eight tentacular arms surrounding a mouth and a tubular funnel which jets water through the mantle. The octopus has no internal skeleton. Its body is completely soft and flexible. With the beak being the only hard body part, an octopus can squeeze its body through a hole as small as its mouth.
Considered the most intelligent of the invertebrates, the octopus can use numerous strategies to defend or hide against predators, including the expulsion of ink to confuse them, the ability to jet quickly through the water, and their instantaneously changing camouflage. They have pigment cells and specialized muscles in their skin to change in the blink of an eye and match the color, shape and texture of the surrounding area. In some species, the mantle, or "head," can take on the spiky appearance of seaweed or the bumpy surface of the rock it's hiding on or in. They inhabit many areas of the tropical ocean, including coral reefs or pelagic waters depending on the species.
The Day octopus, which is the most commonly seen octopus in Hawaiian waters, can be found searching for food during the day, floating over reefs and quickly hiding if startled. They mainly prey on crabs, molluscs and occasionally unsuspecting small fish swimming by.
Maui Ocean Center photo
The Day octopus, the most commonly seen octopus in Hawaiian waters, can be found searching for food during the day, floating over reefs and quickly hiding if startled. The octopi mainly prey on crabs, molluscs and occasionally unsuspecting small fish.
The life of an octopus is short-lived, only several months up to five years depending on the species. So in the beginning, it is important for them to grow quickly. Once they reach adulthood, the reproduction of an octopus will unfortunately mean the end. After the male deposits the sperm into the female's mantle cavity, it dies only a few months later. The female will stay around to protect and care for her eggs anywhere from two to 10 months. Once they hatch, they are on their own and little is known about the early lives of octopi.
The internal anatomy of an octopus is quite detailed, with all of its internal organs held in its mantle. It also has three hearts, important for its high metabolic rate and active lifestyle. Two branchial hearts pump blood up to the gills while the third systemic heart pumps blood through the rest of the body. Most of its neurons are found in its arms, which all contain suction cups and move like they have a mind of their own.
The next time you are snorkeling or diving, do not be so quick to swim around. If you take your time and look closely, you may find an octopus coming out to hunt, and only when it's moving will your eyes pick it up. Don't blink, its texture and color-changing body is captivating to witness.
* Larissa Treese is the head aquarist and beach cleanup coordinator at Maui Ocean Center. "Ka Mo'olelo Moana," or "the Ocean Story," is a monthly column submitted by the Maui Ocean Center. The center is open from 9 a.m. to 5 p.m. daily in Maalaea. For more information, call 270-7000.