Octopus farming. (Photo: YouTube/Cicese)

Mortality of octopus offsprings in captivity reduced

MEXICO
Tuesday, April 10, 2012, 01:30 (GMT + 9)

Researchers at the Aquaculture Department of the Centre for Scientific Research and Higher Education of Ensenada (Cicese) managed to reduce the mortality of offsprings of three species of octopus with high commercial and ecological value.

During the experiments, scientists found that up to 40 per cent of the offsprings in captivity had survived.

The Department of Aquaculture of Cicese researched three species of octopus: the Californian octopus (Octopus bimaculoides), the red octopus (Octopus rubescens) and the two-spot octopus (Octopus bimaculatus).

As part of this study, the specialists provided the octopuses with food based on brine shrimp, a small crustacean that is used to feed aquarium fish.

The director of the Department, Mónica Hernández, stressed that harvest in early stages is the bottleneck in octopus aquaculture.

Some species of octopus lay small eggs and others large ones.

During the octopus life cycle, the male specimen introduces its third arm, modified into a copulatory structure responsible for depositing the spermatophore (a sort of box containing the sperms) in the oviduct of the female specimen.

When the female specimen reaches maturity and there are enough resources to feed the offsprings, the eggs mature to be fertilized by the sperms.

This means that females decide when and where they will reproduce so they conduct parental care of their offsprings.

The team led by Hernández has studied the effect of the prey size of the octopus offsprings.

According to their observations, the paralarvae take prey of their own size, that is to say, about three millimetres.

To better control mortality, the researchers had to make separate shelters and feed them on mussels, squid and shrimp.

Besides, they have observed the diurnal and nocturnal behaviour of the red octopus, their aggressive movements when other specimens were too close and their movement preferences, among other issues.

By varying the temperature, it was possible to see several changes in the octopus colour, from a light shade to red. Furthermore, it was possible to check that they were trying to hide their arms for camouflage.

In this regard, Hernández explained that it is likely that this behaviour is helpful for them to protect their arms because the suction cups are located there and they are used to detect textures, substrates and to catch their prey.

Octopuses are considered to be the most intelligent invertebrate species, understood as the ability to learn from experience and solve problems.

These cephalopods have a highly developed nervous system and an ability to solve problems, overcome obstacles and memorize patterns.

By Analia Murias
editorial@fis.com
www.fis.com

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