Dumbo, the Octopus

Let's visit the deep seas into the world of octopi.

If one were of such inclination as to find octopuses cute (generally, humans aren't), the dumbo octopuses are, without doubt, the cutest of the octopuses. The dumbo octopuses are a genus (containing 24 species) of umbrella octopuses (Opisthoteuthidae); unlike the ubiquitous popular image of ‘the octopus’, their arms aren’t separated tentacles. The arms are connected with webs of skin which, when the tentacles are spread apart, make them resemble opened umbrellas. If that is not enough to rouse interest in these cephalopods, consider that their most prominent feature is their ear-like fins that evoke the image of Disney’s eponymous cartoon elephant. They are also called, somewhat less whimsically, Grimpoteuthis.

Of all known octopus species, dumbo octopuses inhabit the deepest levels of the open ocean. They have been found in at least four of the five oceans i.e., Atlantic, Pacific, Indian and Antarctic oceans, and most species in the genus are found in depths of approximately 3000 to 4000 metres (9800 to 13000 feet). Their range seems to extend down to depths of possibly 7000 metres, extending into trenches below sea level. The deepest one observed in situ (in its natural environment, as opposed to being an open-net trawl sample) was at the depth of 6957 metres in the Indian ocean.

Due to their remote habitats, not much is known about them. However, it has been observed that they do not employ the jet-propulsion mode of locomotion that is characteristic of other cephalopods. They seem to actively move around most frequently by fin-swimming or crawling on the sea floor, which requires less energy. This could be because in deep sea, high speed is not as advantageous as the conservation of energy. They primarily feed on small-sized organisms with low swimming speeds, which also, presumably, conserves energy.

As fantastical as dumbo octopuses are to behold, sadly there are certain characteristics, which have made their shallow-water cousins immensely popular, but which the dumbos lack. They cannot, for example, shoot ink because they lack ink sacs (considered another adaptation to deep-sea life), nor can they change colour. They are usually orange/red/purple in colour.

Studies on reproduction in species closely related to the dumbo octopuses, indicate possible important differences between them and more well studied octopods, notably “… in lack of seasonality of spawning and the continuous production of eggs (females) and spermatophores (males) in adult individuals...”. This reflects that they reproduce regardless of seasons. Mating in these species has never been observed and the males also lack the hectocotylus (one of the arms of male octopuses that stores and transfers sperm packets), which is present in other octopuses. Unlike other octopuses, females lay single large eggs that they attach to hard materials on the sea floor (like deep sea corals). The eggs take much longer to hatch (at least three years) and females do not guard the eggs. The dumbo octopuses hatch as competent juveniles.

It is only recently that we have been able to collect pictures and footage of these elusive creatures in their natural habitat to any large degree. One look at their ethereal forms, undulating and flying through the water, can mesmerize any onlooker.

Photo Credit: NOAA Ocean Explorer and NOAA Photo Library