Mimic octopus

Mimic octopus
Scientific classification
Kingdom:	Animalia
Phylum:	Mollusca
Class:	Cephalopoda
Order:	Octopoda
Family:	Octopodidae
Subfamily:	Octopodinae
Genus:	Thaumoctopus Norman & Hochberg, 2005
Species:	T. mimicus
Binomial name
Thaumoctopus mimicus Norman & Hochberg, 2005

The mimic octopus, Thaumoctopus mimicus, is a unique species of octopus capable of impersonating other sea animals. Most octopi are famous for being able to change their skin color and texture in order to blend in with their surrounding background, such as algae-encrusted rock and nearby coral. This is done through pigment sacs known as chromatophores. The mimic octopus does contain these chromatophors, and does have the ability to blend in with backgrounds as well. However, what makes the Mimic octopus different from its relatives is its ability to take the shape of not only objects, such as coral and rock, but also some animals. The mimic octopus is the only known aquatic species to be able to impersonate an array of different sea animals via behavior. Although many animals who can imitate a different species to avoid or intimidate predators, the mimic octopus is the only one who can choose from many types of forms depending on what predator they are trying to elude.

Origin and Discovery

The mimic octopus was first discovered off the coast of Sulawesi, Indonesia by a group of scientists in the early 1990’s. The species was thought to only inhabit the islands of Indonesia until one was spotted just last year near the Great Barrier Reef by Darren Coker. Coker spotted the octopus on a shallow sand flat near Lizard Island during a super low tide on the afternoon of July 4, 2012.

Appearance

The Mimic octopus is a smaller octopus, growing to an average length of about 60cm, roughly two feet, and their tentacles grow to be 25 inches long, with a diameter about the same as a pencil at their widest. The octopus’s natural color is a light brown/beige color. However, they are usually a more noticeable color of striped white and brown to scare off predators by appearing to be poisonous.It is unknown whether the mimic octopus is in fact poisonous to its predators. However, it is assumed that they are not considering that if they themselves were poisonous, then there would be no need to camouflage themselves as all these other poisonous sea animals.

Behavior

It uses a jet of water through its funnel to glide over the sand while searching for prey, typically small fish, crabs, and worms, protected by its apparently Batesian mimicry of aposematic animals. It also uses aggressive mimicry to approach wary prey, for example mimicking a crab as an apparent mate, only to devour its deceived suitor. It also prefers river mouths and estuaries, as opposed to reefs which are usually preferred give more shelter to other types of octopus. This is because it is able to impersonate poisonous fish; therefore it is hiding out in the open.

Mimic octopus showing a variant pattern

Mimic octopus’s strategy is quite impressive. Mimicry is a common survival strategy in nature, certain flies assume the black and yellow stripes of a bee as a warning to potential predators, but the mimic octopus is the first to mimic more than one species. The mimic octopus is the first of its kind to possess the ability. It is unknown just how many animals the mimic octopus knows how to morph into. What is known is that most of the animals we do know of that it chooses to mimic are poisonous. This information adds to the likelihood that the shape shifting that the octopus is doing is a deliberate survival strategy and not just over observant scientists seeing more than is actually there. Some of the more common animals the mimic octopus pretends to be are the following:

Lion fish- The lion fish is a poisonous fish with the brown and white stripes and spines that trail behind it on all sides. When the octopus changes its color and shapes its eight legs to look like spines, it is indeed conceivable that to the eyes of a potential predator, what might otherwise look like a tasty snack, appears in fact as a highly venomous creature that should not be messed with.

Sea snake – If under attack, a mimic octopus may hide completely in a hole except for two of its legs, which it sticks out in opposite directions. What remains in view is a long thin object with white and black bands running across the elongated body. Again the prospect of tangling with the highly venomous sea snake is something many predators would not dare to do, and they therefore may swim off leaving the octopus to live another day.

Flatfish- By pulling its arms together on one side, and flattening out his body while moving forward along the ocean floor, the mimic octopus makes itself appear like a flatfish.

Jellyfish- The Mimic Octopus will act as a Jellyfish sometimes to scare off certain predators. It does this by puffing up its head and siphon and letting its arms trail behind it. The octopus will then impersonate the motions of a jellyfish swimming by going to the surface and then slowly sinking with its arms spread evenly around its body.

Observed Behavior

The so-called ‘mimic octopuses’ of tropical Indonesia are reputed to mimic up to 13 species of other local marine organisms. Mimicry of a local, abundant flounder was observed; nearly 500 episodes were analyzed. Both octopus species mimicked the shape, swimming actions, speed, duration, and sometimes the coloration of swimming flounders. During flounder mimicry, octopuses were actively moving and conspicuous, whereas immediately before and after flounder mimicry, they were camouflaged and motionless (sitting or very slowly crawling). Furthermore, when motionless, the octopuses assumed body patterns and postures that resembled small sponges, tube-worm tubes, or colonial tunicates, which were among the few objects in the open sand habitat. The key finding was that octopuses used flounder mimicry only when their movement would give away camouflage in this open habitat. In all cases, octopuses used mimicry as a primary defense. The mimic’s behaviour remained undiscovered for years because its dull homelands are poorly studied. But it is precisely this barren nature that has provided the impetus to evolve such amazing behaviour.

This animal is intelligent enough that it is able to discern which dangerous sea creature to impersonate that will present the greatest threat to its current possible predator. For example, scientists observed that when the octopus was attacked by territorial damselfishes, it mimicked the banded sea snake, a known predator of damselfishes.

Eating habits

The mimic octopus can either be classified as a hunter or a forager. It is believed to be a hunter because scientists have observed and recorded the octopus having the ability to stalk prey and hunt down small fish and catch them. More often, however, the Mimic Octopus can be seen foraging for food. It does this by using a jet of water through its siphon to glide over the sand while searching for prey, and using its slender tentacles to reach into crevices in coral, as well as holes in the sand, and use its suction cups to grab small crustaceans and eat them. Because the Mimic Octopus prefers to live in shallow, murky waters, it is believed that its diet consists almost exclusively, of small fish and crustaceans. That is because those are the only two animals that are common to those conditions that a mimic octopus can survive on. They are believed to be carnivores, and are not known to eat any type of plant or vegetation.(Maculay 2012) Living in the tropical seas of Southeast Asia, it was discovered in 1998 off Sulawesi and in 2010 was also found in the Great Barrier Reef. The octopus mimics other animals using changes in both coloration and body posture; like other cephalopods it can also mimic its background.

As mentioned earlier, the mimic octopus varies its mimicry according to the situation. For example, when threatened by damselfish, an individual appeared as a black and yellow banded sea snake, a damselfish predator.

The mimic octopus should not be confused with Wunderpus photogenicus, which has fixed white markings.

Habitat

Mimic octopus showing typical pattern

The mimic octopus lives in nutrient-rich estuarine bays of Indonesia and Malaysia primarily in shallow warm waters about 15 meters deep.It prefers obscuring murky and muddy sea floors to blend in with its natural brown, beige color.

Bibliography

• Butvill, David B. The Changeling. Current Science. October 7, 2005.
• Hearst, M., & Noordeman, J. (2012). Unusual creatures: A mostly accurate account of some of the Earth's strangest animals. San Francisco: Chronicle Books. [children's book]
• PZ Myers (29 November 2004). "Indo-Malayan mimic octopus". Pharyngula. Archived from the original on 2008-09-16. 
• Norman, Mark D.; Finn, Julian; Tregenza, Tom (2001). Dynamic mimicry in an Indo-Malayan octopus. Proceedings of the Royal Society, 268, p. 1755–1758.
• Norman, Mark. Masters of Mimicry. Nature Australia. Spring 2002, vol 27, Issue 6, p.38.
• L. A. Rocha, R. Ross and G. Kopp. Opportunistic mimicry by a Jawfish. Coral Reefs - Journal of the International Society for Reef Studies. December 10, 2011.
• Norman, Mark D. & Hochberg, F. G. (2005) The "Mimic Octopus" (Thaumoctopus mimicus n. gen. et sp.), a new octopus from the tropical Indo-West Pacific (Cephalopoda: Octopodidae).