The Ecology

A journal of how things fit into our environment

I received lots of questions and comments about this picture recently after it was posted on Reddit.  What is it?  Is it a type of clam?  Is it alive?

In actuality, the truth is much stranger.

This animal, the piure (Pyura chilensis), isn’t closely related to clams. It’s not closely related to sea urchins. It’s not closely related to sponges, either.

It’s closely related to us.

This is a tunicate, or more accurately a sea squirt, which shares a closer common ancestor with the animals we descended from. It’s in the same phylum as humans are, Chordata. Vertebrates are simply a subphylum of this taxonomy.

Isn’t life great?


Could you describe the picture? Is this a single specimen and is the “stone” just a shell or something?


The “stone” part is analagous to a shell, as it protects the organism, but it’s actually a compound that is made up of “tunicin.”
Similar to how plants use cellulose to protect and increase the integrity of their tissues, tunicates use tunicin, a similar sugar, to strengthen their mantles.
The mantles will have a few openings in it for their siphons. One siphon leads to the mouth while another is for waste and other secretions, but I may be wrong about that.
The heart, gut, intestines and reproductive organs are usually located under the mouthparts and atrium and are attached to the sea floor, since the animal is completely sessile. It’s a good way for minimizing danger!
This may, in fact, show a few different animals, as many tunicates do live in tight little groups like that.

I received lots of questions and comments about this picture recently after it was posted on Reddit.  What is it?  Is it a type of clam?  Is it alive?



In actuality, the truth is much stranger.



This animal, the piure (Pyura chilensis), isn’t closely related to clams. It’s not closely related to sea urchins. It’s not closely related to sponges, either.



It’s closely related to us.



This is a tunicate, or more accurately a sea squirt, which shares a closer common ancestor with the animals we descended from. It’s in the same phylum as humans are, Chordata. Vertebrates are simply a subphylum of this taxonomy.



Isn’t life great?



Could you describe the picture? Is this a single specimen and is the “stone” just a shell or something?



The “stone” part is analagous to a shell, as it protects the organism, but it’s actually a compound that is made up of “tunicin.”



Similar to how plants use cellulose to protect and increase the integrity of their tissues, tunicates use tunicin, a similar sugar, to strengthen their mantles.



The mantles will have a few openings in it for their siphons. One siphon leads to the mouth while another is for waste and other secretions, but I may be wrong about that.



The heart, gut, intestines and reproductive organs are usually located under the mouthparts and atrium and are attached to the sea floor, since the animal is completely sessile. It’s a good way for minimizing danger!



This may, in fact, show a few different animals, as many tunicates do live in tight little groups like that.

2 years ago

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