All things environmental

Musings about the environment and all it touches, from education to city planning

Life, death and tentacles

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A pacific octopus swimming

It’s pretty easy to get motivated to save from extinction cute or awesome creatures; everyone cares about sea otters or tigers. But should we care about icky, slimy, venomous things with tentacles?  I say we should. One obvious reason is habitat: if we save the habitat of stingey tentacled critters, we also save the homes of sea otters or salmon. But the question goes much beyond that.

Does every species have a right to live? Maybe, but the way they die – or don’t – brings into our very understanding of life and death.

Science still doesn’t understand death. Few of us are likely to live beyond, say, a hundred years. Why? Pacific salmon die after spawning, as if programmed – how? Whether it’s something written in the genetic code, or elsewhere, we still don’t have the first clue about the mechanism of death and senescence.

Like salmon, many male octopus die after mating – but not the females. The females will lay a clutch of eggs, from a few hundreds to several thousand, and guards them. She uses her tentacles to clean them, as well as shoot jets of water on them with her siphon, in order to remove any algae or hydroid or other critters that may settle on her eggs and choke them. She will not leave their sight, and stops eating. This has the advantage of keeping the eggs (and her den) hidden from potential predators; no empty crabs shells, no food wastes or feces to foul the eggs or attrack predators. This seems sensible except that the eggs take six months or longer to hatch; octopus moms will often lose half of their body weight during the process.

Olive was a Giant Pacific Octopus well known to Seattle-area divers. She was seen laying a large clutch of eggs on February 25 2002.

On later dives in following weeks, divers saw her right side up, blowing water through the eggs and caressing them with her arm tips. During the months after the eggs were seen, she would take a piece of herring offered as food by the divers, but later she wouldn’t eat, and blew offered food assertively out of the den.

She guarded her eggs through the summer, seemingly unfazed by the hundreds of divers viewing her. She refused food, she was never seen out of her den, constantly kept the eggs clean, repelled predators and egg eaters, and she grew unresponsive to divers, maintaining a gray colour that gradually turned to translucent white.

Divers witnessed the first of Olive’s eggs hatching September 22. While a few of the paralarvae [octopus babies] swam out of the den during daytime, Olive blew most of them out of the den at night. Her skin had several white ulcers on her arms and mantle, and it had the appearance of rotting away. Divers saw the last hatchlings on October 31. Olive was dead on November 6, 254 days after laying her first eggs. The precise timing of her death is remarkable…although it sounds anthropocentric, it looks as if she clung to life until she knew her eggs hatched.

She was mourned by the local press – but that does little to dispel the mystery. How can this be explained just on the basis of DNA and hormones? We have so much to learn.

turritopsis dohrnii, the immortal jellyfish

turritopsis dohrnii, the immortal jellyfish

Another tentacled creature adds to the mystery of death: it doesn’t. When the jellyfish Turritopsis Dohrnii dies, the cells that make its body start to dissociate, as in any other dying animal. But as the jellyfish decomposes, the individual cells begin to

reaggregate and transform into new hydroid colonies. The whole transformation from medusa to polyp takes place within a mere five days or so of the medusa’s death. This would be roughly the equivalent of a dead butterfly’s cells reforming, all on their own, into a full-grown, fully formed caterpillar. This is the first known example of true biological immortality.

Another tentacled animal, another mystery about death. Even if all we care about is understanding our own death, we need to preserve the environment in which these creatures florish in order to better understand them. But is it all we really care about? Look me in the eye and tell me the fate of Olive, the devoted mother, didn’t move you…

I got the quotes from two books I heartily recommend:
Gershwin, Lisa-ann 2013. Stung! On jellyfish blooms and the future of the ocean. Chicago: U Chicago Press.
Mather, Jennifer, Roland Anderson, & James Wood 2010. Octopus: the ocean’s intelligent invertebrate. Portland: Timber Press.

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Written by enviropaul

October 12, 2014 at 2:53 pm

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