fishing Didn't know this

[ellicat]

Interesting article I happened upon this morning -

Octopuses torture and eat themselves after mating. Science finally knows why. (msn.com)

Many animal species die after they reproduce. But in octopus mothers, this decline is particularly alarming: In most species, as an octopus mother's eggs get close to hatching, she stops eating. She then leaves her protective huddle over her brood and becomes bent on self-destruction. She might beat herself against a rock, tear at her own skin, even eat pieces of her own arms. 

© Provided by Live ScienceThe California two-spot octopus (Octopus bimaculoides) has a circular blue eyespot on both sides of its head.

Now, researchers have discovered the chemicals that seem to control this fatal frenzy. After an octopus lays eggs, she undergoes changes in the production and use of cholesterol in her body, which in turn increases her production of steroid hormones — a biochemical shift that will doom her. Some of the changes may hint at processes that explain longevity in invertebrates more generally, said Z. Yan Wang, an assistant professor of psychology and biology at the University of Washington. 

"Now that we have these pathways, we're really interested to link them to individual behaviors, or even individual differences in how animals express these behaviors," Wang told Live Science. 

Programmed to die

Even as an English-major undergraduate student, Wang was intrigued by female reproduction, she said. When she transitioned into graduate school in science, she kept that interest, and was struck by the dramatic deaths of octopus mothers after they laid their eggs. No one knows the purpose of the behavior. Theories include the idea that the dramatic death displays draw predators away from eggs, or that the mother's body releases nutrients into the water that nurture the eggs. Most likely, Wang said, the die-off protects the babies from the older generation. Octopuses are cannibals, she said, and if older octopuses stuck around, they might end up eating all of each other's young. 

 

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Related: How do octopuses change color?

A 1977 study by Brandeis University psychologist Jerome Wodinsky found the mechanism behind this self-destruction lay in the optic glands, a set of glands near the octopus's eyes that is roughly equivalent to the pituitary gland in humans. If the nerves to the optic gland were cut, Wodinsky found, the mother octopus would abandon her eggs, start eating again and live for another four to six months. That's an impressive life extension for creatures that live only about a year. 

But no one knew what the optic gland was doing to control this cascade of self-injury. 

"From the very beginning, I was really keen to do the experiments that we outlined in the paper we just published, which is essentially juicing the optic gland and then identifying the components of that juice," Wang said. 

Wang and her colleagues analyzed the chemicals produced in the optic glands of California two-spot octopuses (Octopus bimaculoides) after they laid eggs. In 2018, a genetic analysis of the same species showed that after egg-laying, the genes in the optic glands that produce steroid hormones (which are built, in part, with cholesterol components) started going into overdrive. With that study as a guidepost, the scientists focused on the steroids and related chemicals produced by the optic glands in the two-spot octopuses. 

1 of 3 Photos in Gallery©Provided by Live Science

 

 

Fatal changes

They found three separate chemical shifts that occurred around the time the octopus mother laid her eggs. The first was a rise in pregnenolone and progesterone, two hormones associated with reproduction in a host of creatures (in humans, progesterone rises during ovulation and during early pregnancy). The second shifts were more surprising. The octopus mothers began to produce higher levels of a building block of cholesterol called 7-dehydrocholesterol, or 7-DHC. Humans produce 7-DHC in the process of making cholesterol too, but they don't keep any in their systems for long; the compound is toxic. In fact, infants born with the genetic disorder Smith-Lemli-Opitz syndrome can't clear 7-DHC. The result is intellectual disability, behavioral problems including self-harm, and physical abnormalities like extra fingers and toes, and cleft palate. 

Finally, the optic glands also began producing more components for bile acids, which are acids made by the liver in humans and other animals. Octopuses don't have the same kind of bile acids as mammals, but they do, apparently, make the building blocks for those bile acids. 

"It suggests that it is a brand new class of signaling molecules in the octopus," Wang said. 

The bile acid components are intriguing, Wang said, because a similar set of acids has been shown to control the life span of the worm Caenorhabditis elegans, which is commonly used in scientific research because of its simplicity. It may be that the bile acid components are important for controlling longevity across invertebrate species, Wang said. 

Octopuses are hard to study in captivity because they require a lot of space and perfect conditions for them to grow to sexual maturity and breed. Wang and other octopus researchers have now worked out a way to keep the lesser Pacific striped octopus (Octopus chierchiae) alive and breeding in the lab. Unlike most other octopus species, Pacific striped octopuses can mate multiple times and brood multiple clutches of eggs. They don't self-destruct as their eggs get ready to hatch, making them perfect specimens for studying the origin of the morbid behavior. 

"I'm really, really excited to study the dynamics of the optic gland in that species," Wang said.

The researchers published their findings May 12 in the journal Current Biology.

Originally published on Live Science.

[Drop Bear]

Crazy. 

Is there nothing an occy cant do? Delicious, great bait. What more could you want? 

 

[ellicat]

12 minutes ago, Drop Bear said:

What more could you want?

They could ensnare a good snapper and place it on my hook...

[Angry51]

Unreal, just unreal, thanks for posting Brian.

[Kat]

Watched My Octopus Teacher on Netflix a couple of weeks ago.  At the end it shows how this happens.

Well worth a watch.  They are amazing creatures!

[The Mad Hughesy]

1 hour ago, Kat said:

Watched My Octopus Teacher on Netflix a couple of weeks ago.  At the end it shows how this happens.

Well worth a watch.  They are amazing creatures!

agreed. great doco

[Old Scaley]

3 hours ago, christophagus said:

agreed. great doco

I remember watching that show a while ago. At first I thought wow, that is amazing. Then I thought about it and realised that I had fallen into the trap that a good nature documentary never does - the anthropomorphic idea that animals are only here for our pleasure and see and feel things the way humans do. So we have, let’s face it, a bit of a nut job free diving in freezing water and having a quasi sexual relationship with a creature that is so crazy that it beats itself to death after reproducing. We are supposed to believe that an animal which has no understanding of what humans call love takes a fancy to this dropkick who doesn’t know how to live out of the water. Who knows why the octopus behaved the way it did? 

Harsh review, I know. Having said all that, it does make a great story and anything that shows pictures of live fish taken underwater gets my attention. Now Paul the octopus that could predict Germany’s fate in the soccer World Cup some years ago, that was a real octopus!

Good article, Brian.

[Kat]

Hey @Old Scaley.  Yes I understand your comments about the anthropomorphic aspects - also understand depression and how nature can really assist in a cure!  However I think what I took from the doco was more the amazing footage - how the octopus surrounded itself with shells etc to evade the sharks and outwitted a shark trying to eat it etcetera etcetera - still a good watch IMO - considering the Kardashians were the most popular DVD rental back in the day

[Old Scaley]

14 minutes ago, Kat said:

Hey @Old Scaley.  Yes I understand your comments about the anthropomorphic aspects - also understand depression and how nature can really assist in a cure!  However I think what I took from the doco was more the amazing footage - how the octopus surrounded itself with shells etc to evade the sharks and outwitted a shark trying to eat it etcetera etcetera - still a good watch IMO - considering the Kardashians were the most popular DVD rental back in the day

Definitely a great watch @Kat.  The underwater world always astounds me. And definitely didn’t mean to make light of an illness that makes life near impossible for so many people. I need to find an emoji for “tongue in cheek” (or maybe one for “I am being a real a-hole now”).  

[Kat]

No didn't take it like that lol

[Sunny boy]

Very interesting article! I didn't know Octopus has such a dramatic end of life.I wonder if eels do the same after spawning too. Such a mystery!

[AUS-BNE-FISHO]

Thanks for the article Brian. It was a good read. 

Who's caught an octopus before?

Cheers Hamish

[kmcrosby78]

Yes, very interesting Brian, although I can't help but wonder what you were Googling to find this article ........ 

[Junky]

18 hours ago, Kat said:

Watched My Octopus Teacher on Netflix a couple of weeks ago.  At the end it shows how this happens.

Well worth a watch.  They are amazing creatures!

The wife cried at the end of that. 

I love occys. 

[The Mad Hughesy]

@Old Scaley haha i laughed reading your review. agreed though. cool footage none the less

[Drop Bear]

17 hours ago, AUS-BNE-FISHO said:

Thanks for the article Brian. It was a good read. 

Who's caught an octopus before?

Cheers Hamish

I have accidently caught plenty but I want to catch more of them but on purpose. 

I did spear one years ago at a friends place in Sydney. His mum gave me a hard time... and I wasn't aloud to eat it... Therapy has helped.

 

[Drop Bear]

20 hours ago, Old Scaley said:

I remember watching that show a while ago. At first I thought wow, that is amazing. Then I thought about it and realised that I had fallen into the trap that a good nature documentary never does - the anthropomorphic idea that animals are only here for our pleasure and see and feel things the way humans do. So we have, let’s face it, a bit of a nut job free diving in freezing water and having a quasi sexual relationship with a creature that is so crazy that it beats itself to death after reproducing. We are supposed to believe that an animal which has no understanding of what humans call love takes a fancy to this dropkick who doesn’t know how to live out of the water. Who knows why the octopus behaved the way it did? 

Harsh review, I know. Having said all that, it does make a great story and anything that shows pictures of live fish taken underwater gets my attention. Now Paul the octopus that could predict Germany’s fate in the soccer World Cup some years ago, that was a real octopus!

Good article, Brian.

I started to write a similar thing... but chickened out  

I used to (and still do a little) work in the film industry. It has wrecked movies like the Octopus teacher for me... 

[ellicat]

17 hours ago, AUS-BNE-FISHO said:

Who's caught an octopus before?

I caught a blue ringed octopus years ago near the port. Thought it was just some sludge initially. Ended up keeping it for a couple of weeks at home feeding it on yabbies. Let it go back in the river. Quite a pretty creature.

[Drop Bear]

57 minutes ago, ellicat said:

I caught a blue ringed octopus years ago near the port. Thought it was just some sludge initially. Ended up keeping it for a couple of weeks at home feeding it on yabbies. Let it go back in the river. Quite a pretty creature.

That is really cool. We get them on the lease from time to time.