Natures wonders: lobster larvae eat jelly fish,survive (Introduction)

by David Turell @, Friday, September 23, 2016, 19:04 (1061 days ago) @ David Turell

Jelly fish tentacles contain poison, which you have felt if ever encountering them. Certain lobster larvae can eat them and survive by enveloping the barbs in a membrane:

https://blogs.scientificamerican.com/artful-amoeba/why-lobster-larvae-harpoon-proof-the...

"To see the larva of a spiny or slipper lobster is to see an alien creature who devours jellyfish whole -- tentacles first.

"These bizarre larvae - an anomaly among crustaceans -- are called phyllosomas (literally, sheet or leaf body). The larvae have the appearance of transparent squished spiders with silver dollar bodies. Such larvae can reach palm-sized before they dramatically moult into a form that actually resembles a small lobster.
Not all lobsters do this, however. Phyllosomas occur only in the group of lobsters called spiny(rock), slipper, or coral lobsters, which are not closely related to true lobsters.

***

"There's only one little problem. The tentacles that these phyllosomas slurp up like ramen are loaded with harpoon cells that explosively inject venom, as anyone who has suffered a painful jellyfish sting can attest.

***

"The team tested these hypotheses by checking to see whether the nematocysts in Japanese smooth fan lobster larva poo were either discharged or surrounded by a membrane. Then they injected larvae with purified venom to see what happened.
The nematocysts in the feces had indeed been discharged, ruling out that idea that they were just reeeeeally careful chewing their food.

***

"And injecting crude venom extract into the phyllosomas was fatal nine out of ten times. (my bold)

"But the feces were indeed covered with a sheath that the scientists interpreted as a peritrophic membrane, a secreted barrier made of organic material, but not whole cells, that shields the gut from food that fights back. No discharged nematocysts were seen outside this layer.

"One question I have that is not answered by this study is how the larvae digest their food if it is sealed inside a seemingly impenetrable membrane. Perhaps the membrane has a micropore structure to allow digested food particles - but not toxic jellyfish harpoons -- to pass through, a bit like the bag around boil-in-bag rice?
Or perhaps the membrane has openings that aer far away from the fecal pellet - beyond the reach of an individual nematocyst.

"Or perhaps only the nematocysts are somehow segregated into sealed sacks, while the rest of the jellyfish is left outside for digestion. But if that is true, how does the gut know how to precisely separate the nematocysts from the rest of the jellyfish and place them so carefully in the membranes?

"However they do it, it is amazing. These jellyfish-eating lobster larvae are somehow making internal biohazard bags that prevent suicide by sushi."

Comment: My bolded statement shows that this process could have been evolved among the survivors who tried this type of meal. But the author's comments show how difficult this is to evolve, because the special proteins to make the membrane have to be found by a chance hunt and peck evolutionary process a well as developing a gut mechanism invented to produce the membrane, which requires the organization of other coordinated complex proteins. Saltation?


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