It freaks me out that tunicates are chordates. How can a creature's body plan get that bizarre, from a starting point similar to vertebrates? They're not just dissimilar to familiar animals, they're barely recognizable as animals.
Tunicates evolved long before animals that you would recognize as typical vertebrates. In their free-swimming larval state, tunicates do have a "notochord", or nerve chord, running along their head-tail axis. This structure is a kind of proto-spine. The evolution of true vertebrates proceeded from this condition by neoteny, the retention of larval traits in the adult body plan. Pyrosomes look so bizarre compared to a layman's notion of what a chordate should look like because they are colonial aggregations of lots of individual adult tunicates that have resorbed their notochords (I'm pretty sure that's the case, despite what the photo description says).
The article mentions that unless all of the individual organisms die at the same time it is theoretically possible for the colony to live forever. I wonder if we have any way of telling how old a particular colony could possibly be?
> I wonder if we have any way of telling how old a particular colony could possibly be?
Maybe sequencing DNA from a lot of the individual organisms and counting how many differences there are? Older colonies should accumulate the differences, right?
Differences relative to what? A young and old colony are still the same evolutionary distance from their last common ancestor. Even if there was some change in mutation rate once a colony is formed, it would be really hard to measure the difference. Maybe diversity within a colony is a clue?
> When the animal or plant dies, it stops exchanging carbon with its environment, and thereafter the amount of 14C it contains begins to decrease as the 14C undergoes radioactive decay. Measuring the amount of 14C in a sample from a dead plant or animal, such as a piece of wood or a fragment of bone, provides information that can be used to calculate when the animal or plant died.
Once a year we get hundreds of thousands of pyrosomes in our waters. The first time we saw them I spent the whole trip out of the water researching what they might be
FWIW they ended up seeming harmless, my "neighbors" were swimming with them
This thing looks far too much like a digestive tract for me to ever consider going inside it willingly. I suppose after direct observation for a while I might be more comfortable with the creature but I feel like I'd never get past that initial feeling...
It reminds me of a particularly fantastic piece of lore from Skyrim. It's remarkable to come across in real life something similar to what stretched my suspension of disbelief in a fictional setting.
"The Underground Express was a method of transportation employed by the native Argonians in Black Marsh. It involved travelers submerging themselves into a Rootworm's stomach through their breathing holes. The travelers could then leave the Underground Express via the breathing holes as well. The travelers would then travel inside a Rootworm's stomach during their migrations. Notable exits and entrances to the Underground Express during the winter could be found at Gideon and Hixinoag."
That is definitely an interesting application for cancer.
As far as aging though, I would take it with a grain of salt. Strangely, aging doesn't seem to be caused by accumulated DNA copying errors.
Otherwise, each generation of humans would be genetically worse off than the previous generation.
The quote below came to mind.
"Imagine how many times DNA has been reproduced, not just during your lifetime in your own body but since human life began! To understand how amazing this is, consider what would happen if you used a photocopier to copy a document and then used the new copy to make the next copy. If you did this repeatedly, the quality of the copies would deteriorate and eventually become unreadable. Happily, the quality of our DNA does not deteriorate or wear out when our cells repeatedly divide. Why? Because our cells have many ways of repairing DNA copy errors. If that were not true, mankind would long ago have become a pile of dust" - Source: https://www.jw.org/en/library/magazines/g200605/Why-Do-We-Gr...
This article has a picture of a sea turtle taking a nice chomp out of a smaller one. Maybe nothing that eats them ever feels like eating the whole the colony. It would seem it's pretty tough to tear it.
"The Giant Pyrosome is a free-floating, colonial tunicate that is made of thousands of identical clones, together forming a hollow cylindrical structure that can be 60 feet (18 m) long and wide enough for a person to enter."
