Ingenious octopus astonishes researchers

The seas still have many surprises in store for us: for example, the larger Pacific striped octopus displays behaviour that astonishes researchers – and is quite unlike that of a typical cephalopod, whether in terms of mating, egg laying or hunting.

A shrimp walks unsuspectingly along the sandy sea floor. Suddenly, something taps on the front section of its shell. The scared crustacean flees backwards, straight into the awaiting tentacles of its hunter, the larger Pacific striped octopus. Octopuses typically pounce on their prey or poke around in holes until they find something to eat. The larger Pacific striped octopus displays more finesse: “When this octopus sees a shrimp, it compresses itself and creeps up, extends an arm up and over the shrimp and scares it,” explains Roy Caldwell from the University of California. 

Social octopuses

Together with his team, the marine biologist caught 24 of these octopuses and observes them in large aquariums in his laboratory. The researchers wanted to get to the bottom of the rumours about the animals’ unique behaviour. These seemed so strange that no-one has really dared to publish anything about them until now.

It is not just its hunting behaviour that makes this octopus different; it is also unusually sociable. Whereas most octopus species prefer to swim through the sea on their own, the larger Pacific striped octopus can be found in groups of up to 40 of its kind.

Beak-to-beak mating
Beak-to-beak mating

The larger Pacific striped octopus is also like no other when it comes to mating. For other octopuses, this is somewhat of a dangerous activity: the male cautiously tries to insert the tentacle that is acting as his mating arm into the female’s body.  While doing so, the animal always remains at a distance and is ready to flee if the female becomes aggressive or even hungry.

This is all very different in the case of the larger Pacific striped octopus. Here, the male approaches its mate face on until they are positioned beak to beak. “This mating pose had never before been seen in octopuses,” the scientist commented. The male slowly moves his mating arm to the target area while the female even partially wraps him in her arms. This process is not necessarily a tender one: several males were left with clear suction pad marks afterwards. After mating, that is not the end of the couple though. The researchers observed that the animals often lived together in a hole for several days and presumably even shared food.

Uninterrupted egg laying

This could also be to do with another special characteristic of these creatures – the females mate multiple times, even if they have already laid eggs in holes or baby octopuses have already hatched.  During this period, they do not stop eating like other species. They furthermore produce several clutches of eggs. One of the females observed even did this daily for an entire six months. The mothers carefully tend to the eggs, monitor them and move their tentacles over and among the eggs, presumably to clean them.

Mythical creature brought to life

The larger Pacific striped octopus has a magnificent and highly contrasting pattern of spots and stripes. Its natural habitat includes the Pacific coast of Nicaragua and Panama, where it is found at depths of 40 to 50 metres. Although far from inconspicuous, we have only known about this species of octopus since 1977. However, these is still no scientific description of it so it has not yet been given a Latin species name.

Information about its unusual behaviour was first published in 1982. “Observing this octopus and its unbelievable behaviour was almost as though a mythical creature had been brought to life,” the marine biologist commented in description of his findings. “This example is a testament to how little is known about most octopuses,” believes Caldwell. To date, only a handful of the over 300 known octopus species have been thoroughly researched. 

AUTHOR: Tetra GmbH
DATE: 03.06.2016
SOURCE: Roy L. Caldwell et al: Behavior and Body Patterns of the Larger Pacific Striped Octopus; PLOS one; August 2015; DOI: 10.1371/journal.pone.0134152