Gorda Escarpment and Graneledone


TONMO Supporter
Nov 19, 2002
Interesting discovery:

Deep water 'undersea nurseries' have been discovered at the Gorda Escarpment deep sea ridge off Northern California. What makes this unusual is the concentration of the octopus Graneledone, 'the Warty Octopus', and that they share their brooding area with blob sculpin fish doing exactly the same. The ridge contains hydrothermal cold-seeps and these biological 'hotspots' are gathered around the seeps. These breeding areas are thought to be very transitory and are very hard to locate.

Scientists Discover Deep Sea Nurseries
That's really interesting Phil. Previously published accounts of Graneledone eggs were few and far between (I gave a synopsis in a paper co-authored with Tsunemi Kobodera in 1996 - O'Shea, S.; Kubodera, T. 1996. Eggs and larvae of Graneledone sp. (Mollusca, Octopoda) from New Zealand. Bulletin of the National Science Museum, Series A (Zoology), 22(3): 153-164). The Graneledone species has since been described, Graneledone taniwha taniwha (did this in 1999). The Monterey Graneledone species has been called a number of names - G. pacifica and G. boreopacifica, although I think that there are at least two species out there (when I looked at the material that was described), so both names might be valid.

I've only ever found Graneledone eggs (2 lots) on artificial substrata - telephone cables, as did Robson way back in 1932 (also from telephone cables in New Zealand waters). They are extremely rare, so this latest discovery is quite important.

Contrary to popular belief, Graneledone is NOT a genus that is concentrated around areas of hydrothermal or cold-seep activity. It is found everywhere throughout New Zealand waters, more often than not associated with soft sediments. We have two species in New Zealand waters (G. challengeri and G. taniwha). If they brood their eggs then this is a truly remarkable discovery - the eggs are huge (each to 19mm long). It makes them extremely susceptible to bottom-trawl fisheries impact.
Steve, you may be interested to have a look at this link as there is a stunning, if small, photo. Other photos are available via a link but I can't seem to get them to load at the moment.

Nurseries In The Deep Sea

This is from the Monterey Bay Website. Further details are available in the current Issue of Biological Bulletin, Jeff Drazen is the author of the article.
Happy to oblige. :)

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Deep-sea: Fish and octopus brood in close company

On an ocean ridge near the coast of California, biologists have observed deep-sea life forms brooding their offspring for the first time.

According to researchers, a species of grouper (Psychrolutes phrictus) and the deep-sea octopus (Graneledone sp.) have built a number of nests in peaceful proximity, in which they are brooding their eggs like hens.

The marine researchers were set on the animals’ trail by a submersible on the crest of the undersea Gorda Ridge. Fish and octopus are thought to raise their offspring there with regularity during the summer months, at approximately 1600 m depth, reported Jeff Drazen of the Monterey Bay Research Institute at a press conference in Coos Bay, Oregon. It still unclear why the animals choose this close association; the region may encompass a so-called ‘hot spot’ with especially high biological activity, Drazen speculates.

‘The grouper nests look like purple blotches spread over the ground,’ Drazen describes from the submersible’s videorecordings. ‘The parents position themselves either near or directly upon the eggs. When I saw the video for the first time, I was surprised – such behavior has never been observed in deep-sea fish.’ Drazen estimates that the grouper, reaching lengths of 60 cm, lay up to 100,000 eggs.

The researcher and his colleagues first began to notice the nests in August, 2000, when they sent their submersible Tiburon on geological expeditions into the deep. Among other things, Tiburon brought back a sediment probe thickly covered with eggs. The region was accordingly targeted again for investigations of deep-sea life in 2001 and 2002. The researchers will present preliminary findings in the journal Biological Bulletin.

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