How did the male angler fish evolve?

[Jorpho]

So you may be familiar with this Oatmeal comic about the male angler fish. How exactly would this behavior evolve?

Of course I can see why it would be advantageous for the male fishes to stay in close proximity to the female, and how things might have started out with the female laying her eggs and the male subsequently fertilizing them. It might even be advantageous for the male to cling to the female. But how exactly would it go from there to lip-melting and absorption? Is this a common thing in fish?

Attempting to Google predictably brings up a mess of "blah blah hail to the creator this is they way things are".

[Angua]

Apparently it's common in the Ceratiidae family

You might get better results googling that as it's a more scientific name. Let me know what you find!

[AvatarIII]

I wonder if it started off as a symbiotic relationship where the males would be forced to eat the females to survive, because they couldn't find or get anything else to eat, then the females developed a defence mechanism to prevent death by cannibalism, perhaps they secrete some sort of enzyme?

perhaps it turned out that the most successful females secreted just enough enzyme to dissolve the male enough that he becomes subsumed rather than killed, hence the most successful females passed on this ability?

[Izawwlgood]

The males secret the enzyme that dissolves their jaws though, I believe, not the females.

Stepwise, I think it's easy to visualize how this could have happened, especially when you remember sexual dimorphism is a thing. Males that continued expressing angiogenic factors were able to subsist off more than just bits bitten off from the females. Males that chose to never release never lost their mates. The 'males melting themselves to the female', in my opinion, is likely an energy saving mechanism to alleviate the need to cling to the female using energy from jaw muscles.

[AvatarIII]

The males secret the enzyme that dissolves their jaws though, I believe, not the females.

Stepwise, I think it's easy to visualize how this could have happened, especially when you remember sexual dimorphism is a thing. Males that continued expressing angiogenic factors were able to subsist off more than just bits bitten off from the females. Males that chose to never release never lost their mates. The 'males melting themselves to the female', in my opinion, is likely an energy saving mechanism to alleviate the need to cling to the female using energy from jaw muscles.

fair enough. Your theory is good as well, the males that produce the enzyme are more likely to reproduce than ones that just cling, the more enzyme produced, the more likely to reproduce due to being more attached the the female (less likely to be knocked off etc.), the males that produce too much enzyme though, (enough to melt the gonads,) are selected against, therefore it has reached a point where the "Goldilocks" amount of enzyme is produced. That seems pretty logical to me.

[PeteP]

Ah so this is were the concept of combining robots comes from!

[Sizik]

It's kind of analogous to the way egg cells are huge and sperm cells are tiny.