Studying midget octopus

Seaweek article - 09 March 2018

Erica Donlon is in her second year of her Masters in Marine Sscience at the University of Otago studying aging and developmental rates in the lesser known midget octopus.

This species is not as well-known as the common Māori octopus, so their importance to the habitat in which they live is unknown. These tiny octopus are often caught in dredges from scallop and oyster fishing boats because they make homes in empty shells which are then dug up in the dredge. Octopus are known for being escape artists and can easily crawl off the boat after capture, but the impact from this trauma is unknown.

Erica is aiming to gain a greater understanding on the life history of the midget octopus, by creating a growth profile to understand size with age. She is doing this by looking at growth rings in the beak and the stylet (an internal shell) and observing an aging pigment in the optic lobes (nerves behind the eyeball).

Currently, Erica is caring for thousands of baby octopus. Because they are born looking similar to the adults but still have to spend time in the plankton before settling and becoming juveniles, they are termed paralarvae. For her Masters research project, Erica is raising these paralarvae in three different temperatures (24, 17, and 11°C) to study how temperature affects their growth rates. All of this information is being gathered from octopus from the Otago Harbour, Foveaux Strait, and offshore Otago. Octopus from these areas will be compared to see if different populations have different growth rates and to speculate why this would be. This information is important for predicting how these animals will respond to climate change in the future.

Paralarvae

Image above:  Paralarvae

Paralarvae

Image above:  Paralarvae hatching

Midget octopus

Image above:  Midget octopus

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