Caribbean Compass Yachting Magazine - April 2022

GET TO KNOW YOUR CARIBBEAN MARINE LIFE
Meet the Smartest Invertebrates on the Reef: THE OCTOPUSES
by Darelle Snyman
APRIL 2022 CARIBBEAN COMPASS PAGE 28
These quirky cephalopods are some of the most intriguing and bizarre creatures
you will encounter in the underwater world. They have become part of folklore, being
the inspiration for many a sea monster through history, from the fearsome Kraken
to the Caribbean Lusca.
The Lusca is a sea monster said to live around the blue holes near Andros, an
island in the Bahamas. Even the Greek philosopher Aristotle was intrigued by these
creatures, though his opinion was less than flattering. In his History of Animals,
written in 350 BC, he wrote: “The octopus is a stupid creature, for
it will approach a man’s hand if it be lowered in the water, but it is
neat and thrifty in its habits.”
It is impossible not to be fascinated by these soft-bodied creatures
that have three hearts, are shown to be super-clever, and have blue
blood pumping through their bodies. If these charismatic animals
have not yet cast their spell on you, then you will definitely be
enthralled once you have watched the acclaimed documentary “My
Octopus Teacher” on Netflix.
The eight arms that give octopuses their name are among their
most amazing features. The majority of their neurons, approximately
two-thirds, reside in their arms and not their head. As a result, each
of these amazing appendages can touch, taste, and manipulate
objects independently, clearly making octopuses the kings of
multitasking. While some arms are busy taking apart a tasty
shellfish, another can explore a cave for more tasty tidbits.
All octopuses have venom that they inject by means of special
salivary papillae to immobilize their prey. This venom is generally
not harmful to humans; the only exception is the venom of
Australia’s tiny Blue-Ringed Octopus.
Octopuses are masters of camouflage, renowned for their ability to
go through a kaleidoscope of split-second color and texture changes,
allowing them to hide in plain sight. Some octopuses can change
their appearance a thousand times over the course of a day. This
ability does not always aid in distinguishing between the different
octopus species.
There are more than 300 known species of octopus and they are
found in every ocean. The following three species are the ones you
are mostly likely to encounter in the Caribbean.
The Common Octopus
First up is the Common Octopus (Octopus vulgaris), and there is
definitely nothing ordinary about this octopus. Its uninspiring name
relates to the fact that it is the most wide-ranging octopus species
in the ocean.
The Common Octopus, unlike many of its kin, is often active during the day and
there are two features to look out for to identify this engaging creature. The Common
Octopus has no ring around its eyes and the suckers that cover its eight arms have
a dark edge around them.
The extremely clever Common Octopus loves to keep its home
hidden and often protects it with a variety of objects such as shells,
stones and even cans and glass bottles. I had a fun interaction with
one of these little critters recently in the shallows in Isla Mujeres,
Mexico. I discovered its den by accident when I surprised it, causing
it to make a mad dash for its home. When I dove down I found it had
moved a tin can in front of the den’s entrance. I proceeded to move
the can away to take a closer look. Since I was snorkeling, I went up
for air. When I dove down again I saw that the little upstart moved
the can back to cover the entrance once more. How special is that!
There are numerous stories detailing the amazing antics of these
super-smart creatures. One such tale is about a rabble-rouser
called Otto who caused quite the commotion at Germany’s Sea Star
Aquarium. The aquarium suddenly started experiencing electrical
failures during the night, and even though the electricity was
restored, the problem persisted. Puzzled staff started to stay
overnight to identify the root of problem. It was soon discovered that
Otto was the culprit, causing the aquarium’s whole electrical system
to short out every night by spraying the 2,000-watt overhead
spotlight with jets of water.
Another headache for aquarium staff is to keep these critters
contained. Their soft bodies allow them to go through impossibly
small openings and fit perfectly into the smallest of nooks and
crannies, making them expert escape artists.
The Common Octopus needs to be extra vigilant as it goes about its
daily business, considering the array of predators that want to feed on
it. This poor creature is hunted by sharks, moray eels, seals, sperm
whales and birds. Luckily, like its kin, it has an arsenal of strategies
to escape or defend itself. Two of these adaptations have been
mentioned already: its amazing abilities to hide in plain sight and to
squeeze its soft body into the smallest cracks and crevices imaginable.
When these fail to produce the necessary results it will expel jets
of water from its mantle to make a quick escape. In this getaway process it might
also release a cloud of black ink. This ink cloud not only obscures its escape but also
harms its enemies when sprayed into their eyes. This potent defense concoction
contains a compound called tyrosinase that causes a blinding irritation while also
disrupting the attacker’s sense of smell and taste.
The Caribbean Reef Octopus
The Common Octopus shares the reef habitat with its rather bulky relative, the
Caribbean Reef Octopus (Octopus briareus). The two species are often mistaken for
one another and their ability to undergo mesmerizing color changes does muddy the
waters when it comes to identification. The best way to tell them apart is to look at
the eyes. The Caribbean Reef Octopus has a distinctive ring around each eye.
It distinguishes itself further from its relative in having arms that often differ in
length and thickness. Its mostly mottled red-brown color gives it a marbled
appearance. What makes it a standout is its ability to rapidly switch from an
iridescent blue-green color to white and then back to its original coloration.
You are most likely to encounter this shy, reclusive octopus at night when it comes
out to prowl the bottom, hunting for food. When feeding it becomes a fearsome foe
that spreads its webbed arms like a huge net, engulfing entire coral heads. The prey
trapped within this net has very little chance of escape. The Caribbean Reef Octopus
uses its powerful beak and radula to tear its prey apart.
Its favorite meal of all is the Caribbean Spiny Lobster, which obviously does not
love being eaten by this eight-armed foe. It has been discovered that the Spiny
Lobster has developed an interesting method to escape the octopus’s strong, suckerbearing
arms. It makes a rasping or buzzing sound called stridulation to deter a
hungry octopus. A study showed that when lobsters stridulated upon capture they
Above: Octopuses, like this Common Octopus, are masters of camouflage. Some can
change their appearance a thousand times over the course of a day.
Below: The Caribbean Reef Octopus has arms that often differ
in length and thickness.
escaped every time, while those that remained silent were caught and eaten 40
percent of the time. It is clear that octopuses do not like noisy food!
These special creatures seem to be the perfect test subjects for a wide variety of
studies. Breeding studies have shown that the solitary nature of Caribbean Reef
Octopuses might actually be a necessary survival strategy. It has been discovered that
when they are reared in close quarters with their own kind they develop certain
diseases. One such study has shown them to develop fatal ulcers when reared together,
but not when reared alone. They actually like their time alone so much that if another
octopus dares to disturb them in their lair, it runs the risk of being killed and eaten.
Caribbean Reef Octopuses might be solitary, but they are not attached to their
dens. They move often during their lives, which seldom last past the ten- to
12-month mark. Sadly, mating signals that the life of an octopus has come full circle
and they die soon afterwards. The male initiates mating by wrapping around the
female and attaches a sperm packet to the female using a modified third right arm
called a hectocotylus. The male dies shortly after mating, but the female will
continue to live until the eggs hatch. During this time the female stops eating and
focuses all her attention on the protection of her eggs.
—Continued on next page