The mimic octopus ( Thaumoctopus mimicus ) is a fascinating cephalopod species native to the Indo-Pacific region. Discovered in 1998 off the coast of Sulawesi, Indonesia, this creature has captivated scientists and nature enthusiasts alike with its remarkable ability to imitate a wide array of marine animals. This article delves into the diet and feeding habits of the mimic octopus, as well as its unique mimicry behavior and other aspects of its biology.
Physical Characteristics and Habitat
The mimic octopus is a relatively small octopus, reaching a total length of about 60 cm (2 ft), including its arms. Its arms are about the diameter of a pencil at their widest. It has small horns protruding over each eye. The octopus' natural color is light brown/beige, which helps it blend with its surroundings. However, it can quickly adopt a more noticeable hue of striped white and brown.
This species is primarily found in shallow, murky waters with sand or silt at depths of less than 15 m (49 ft). It prefers river mouths and estuaries, where it can easily blend in with its surroundings, often sheltering in the burrows of other animals. The mimic octopus has been found to inhabit the Indo-Pacific, ranging from the Red Sea in the west to New Caledonia in the east, and Gulf of Thailand and the Philippines in the north to the Great Barrier Reef in south. Most documented records are from Indonesia.
Diet and Foraging Behavior
The mimic octopus is a daylight hunter and forager, actively searching for food during the day. Its diet primarily consists of small fish, crustaceans, and worms that burrow into or crawl across the soft seafloor. The mimic octopus uses a jet of water through its funnel to glide over the sand while searching for prey. It uses its slender arms to reach into crevices in coral, as well as holes in the sand, and uses its suction cups to grab small crustaceans and eat them. Each arm is lined with two rows of chemotactile suckers that can taste and touch at the same time.
Unlike ambush predators, the mimic octopus is an active forager, a bold move considering that most other octopuses stick to the shadows and are nocturnal. Some individuals have been observed moving across open sand while impersonating flatfish, using the disguise to avoid predators and sneak up on unsuspecting prey.
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The mimic octopus has also been observed foraging through subterranean tunnels, entering a tunnel completely and emerging from another hole up to 1m from the entrance point, searching for food.
Cannibalism has also been observed in mimic octopuses, even when other food sources are available. Experts believe these cannibalistic acts are not driven by survival needs.
The Art of Mimicry: A Survival Strategy
The mimic octopus is most famous for its ability to impersonate other marine animals. This remarkable behavior serves two primary purposes: defense against predators and, in some cases, deceiving prey.
Defensive Mimicry
When threatened, the mimic octopus can transform its body to resemble various venomous or unpalatable creatures, deterring potential predators. Some of the animals it commonly imitates include:
- Lionfish: The octopus spreads its arms wide and moves slowly to resemble the spiny, venomous lionfish. It holds its arms out radially to mimic the fish's spines.
- Sea snake: The octopus hides six arms in a hole and stretches two others in opposite directions, waving them to mimic a banded sea snake. It changes color, taking on the yellow and black bands of the toxic sea snake.
- Flatfish: The octopus flattens its body and glides along the seabed, arms trailing behind, mimicking the movement of a flatfish.
- Jellyfish: By inflating its mantle and trailing its arms behind it, the octopus imitates the form of a jellyfish.
- Zebra sole: The octopus holds all eight arms behind it as it uses its siphon to swim, resembling a zebra sole.
- Sea Anemone: The Mimic Octopus can also bury itself entirely, leaving only its striped arms waving like stinging anemone tentacles
Scientists believe this creature may also impersonate sand anemones, stingrays, mantis shrimp and even jellyfish.
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The mimic octopus often chooses which animal to copy based on the threat it faces. For example, when confronted by damselfish, known predators of sea snakes, the octopus has been observed mimicking a banded sea snake.
Aggressive Mimicry
In addition to defensive mimicry, the mimic octopus also employs aggressive mimicry to approach wary prey. By imitating a crab as an apparent mate, the octopus can deceive its suitor, drawing it closer before devouring it.
How it Works
The mimic octopus's ability to transform its appearance is made possible by specialized pigment-containing cells called chromatophores in its skin. These cells, controlled by the nervous system, allow the octopus to change its color and patterns rapidly to match its surroundings or imitate other animals. The octopus also can alter its body shape and posture to further enhance its mimicry.
Each of its eight arms has a mini-brain, and it has a centralized brain in its head. Each of its eight arms can taste, touch, and move independently. The mimic octopus has also been observed to mimic sessile animals such as small sponges, tube worm tubes, or colonial tunicates.
Intelligence and Learning
Octopuses are among the most intelligent invertebrates on Earth, and the mimic octopus is no exception. They have nine brains - one mini-brain in each arm and another in the center of their bodies. Each arm can independently taste, touch and perform basic movements, but all arms can also work together when prompted by the central brain.
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Their brains are especially large for an invertebrate. Their brains contain roughly around 300 million neurons and their arms contain roughly 50 million neurons. Each of their eight arms has its own neural network. This allows them to a have better control, sense of touch, and decision-making abilities. Their brains allow for rapid learning, camouflage, mimicry, memory, vision, and motor control.
The mimic octopus's ability to mimic a variety of animals suggests that this species is observing and learning about its environment. This highlights the high level of intelligence and cognitive flexibility of these creatures.
Reproduction and Lifespan
The mimic octopus has a reproduction process where the male places a sack of sperm inside of the mantle of the female using its mating arm, called a hectocotylus. The male will die within a few months of this process taking place. As she lays strings of eggs she will use the sperm to fertilize them. She will keep the strings of eggs tucked protectively under one of her arms. Her suckers will prevent them from falling into the water as she moves around. As the eggs are ready to hatch she too will die. The young Mimic Octopus will have to fend for themselves from the instant they hatch.
Like many shallow-water octopuses, the Mimic Octopus likely has a short life. While the lifespan of the Mimic octopus hasn’t been directly studied, scientists estimate it to be around 9 to 12 months-based on comparisons with similar shallow-water species.
Threats and Conservation
The mimic octopus isn’t currently listed on the IUCN Red List. These shape-shifters live in shallow, silty estuarine environments, and these areas remain threatened by coastal development, pollution, and bottom trawling. Because they’re rarely seen and often misidentified, it’s hard to know exactly how many are out there. But recent sightings in Mozambique and the Arabian Sea show they may be more widespread than we thought.