Saturday, August 2, 2014

[Cephalopoda • 2014] Deep-Sea Octopus Graneledone boreopacifica Conducts the Longest-Known Egg-Brooding Period of Any Animal


[upper] Graneledone boreopacifica. The subject female brooding her eggs on a nearly vertical rock face. Near the octopus are two Lithodid crabs. The mantle length of the specimen, when first encountered, was 21.2 cm.
[lower] Close-up of the egg capsules in December, 2010. In month 43, the mantles of the embryos can be seen in the apex of each capsule and their dark eyes are apparent.
doi: 10.1371/journal.pone.0103437.g001

Abstract
Octopuses typically have a single reproductive period and then they die (semelparity). Once a clutch of fertilized eggs has been produced, the female protects and tends them until they hatch. In most shallow-water species this period of parental care can last from 1 to 3 months, but very little is known about the brooding of deep-living species. In the cold, dark waters of the deep ocean, metabolic processes are often slower than their counterparts at shallower depths. Extrapolations from data on shallow-water octopus species suggest that lower temperatures would prolong embryonic development periods. Likewise, laboratory studies have linked lower temperatures to longer brooding periods in cephalopods, but direct evidence has not been available. We found an opportunity to directly measure the brooding period of the deep-sea octopus Graneledone boreopacifica, in its natural habitat. At 53 months, it is by far the longest egg-brooding period ever reported for any animal species. These surprising results emphasize the selective value of prolonged embryonic development in order to produce competitive hatchlings. They also extend the known boundaries of physiological adaptations for life in the deep sea.


Figure 1. Graneledone boreopacifica. The subject female brooding her eggs on a nearly vertical rock face at a depth of 1397Neptunea amianta. Near the octopus are two Lithodid crabs and a non-brooding Graneledone can be seen above and to the right of the brooder. The mantle length of the specimen, when first encountered, was 21.2 cm.

Figure 4. Close-up of the egg capsules in December, 2010. In month 43, the mantles of the embryos can be seen in the apex of each capsule and their dark eyes are apparent.


Figure 2. Graneledone boreopacifica, identification marks.
Images of a brooding female over the course of 53 months, each showing the identifying scar on the web between arms R1 & R2. In each frame the characteristic scar is outlined by an oval. a, April, 2007, crawling across the sediment toward the brooding site. b, May, 2007, on the rock face, covering the recently deposited clutch of eggs.
The arrow points to a circular scar on arm L1, which provides additional confirmation. c, May, 2009. d, October, 2009.
The second arrow points to a scar on arm L2. e, December, 2010. f, September, 2011.



Bruce Robison, Brad Seibel and Jeffrey Drazen. 2014. Deep-Sea Octopus (Graneledone boreopacifica) Conducts the Longest-Known Egg-Brooding Period of Any Animal. PLoS ONE. 9(7): e103437. 

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