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Domanda
Perché le stelle marine sono considerate una specie chiave di volta?
Risposte
02/17/2022
Palestine
Robert Paine, the guy who originally came up with the idea of keystone species was studying invertebrates in Makah Bay, Washington, USA.
(image source: wikipedia) In the bay were a bunch of California mussels (Mytilus californianus). The mussels have a very thick and strong shell to protect them from being eaten. It works pretty well, there are no animals who can pry the mussel shell open against the mussel's grip.
(image source: wikipedia) Paine found that the only thing that could eat the mussels were pisaster starfish (Pisaster ochraceus). Even the starfish couldn't get the mussel shells open, but they could squirt digestive enzymes through a tiny hole in the shell and digest the mussels until the mussels couldn't hold the shell shut any more.
(image source: wikipedia) The mussels all have to have a tiny hole in their shell for the byssus, which is a mass of adhesive threads that attach it to rocks, so there's always an opening starfish can use to digest the mussel enough that they can pull its shell open.
(image source: feather3 on underground.com) Since pisaster starfish are the only thing in Makah bay that can eat California mussels, they are absolutely essential to the ecosystem of Makah bay. If all the pisasters disappeared somehow, mussels would completely take over the bay: they live up to 20 years and nothing can eat them. Every rocky spot would be completely covered in mussels and there would be no room for anenomes or clams or seaweed or anything else, and no food for any other animals.
So in the Pacific Northwest, pisaster starfish are a keystone species in tide pools and intertidal zones. They keep mussels from completely taking over everything.
Further south, in California, a different species is the keystone that keeps mussels under control: sea otters. They use tools to eat mussels. Instead of trying to get the shell open, they just use their hands to hit mussels with rocks and break the shells. Here's a video of a sea otter smashing a mussel with a rock:
Here's Robert Paine's paper, proposing the concept of a keystone species, using pisaster starfish and california mussels as an example:
Paine, R.T. (1969). A Note on Trophic Complexity and Community Stability. The American Naturalist 103 (929): 91–93.
Ilgiardino.wiki
Robert Paine, the guy who originally came up with the idea of keystone species was studying invertebrates in Makah Bay, Washington, USA.
(image source: wikipedia)
In the bay were a bunch of California mussels (Mytilus californianus). The mussels have a very thick and strong shell to protect them from being eaten. It works pretty well, there are no animals who can pry the mussel shell open against the mussel's grip.
(image source: wikipedia)
Paine found that the only thing that could eat the mussels were pisaster starfish (Pisaster ochraceus). Even the starfish couldn't get the mussel shells open, but they could squirt digestive enzymes through a tiny hole in the shell and digest the mussels until the mussels couldn't hold the shell shut any more.
(image source: wikipedia)
The mussels all have to have a tiny hole in their shell for the byssus, which is a mass of adhesive threads that attach it to rocks, so there's always an opening starfish can use to digest the mussel enough that they can pull its shell open.
(image source: feather3 on underground.com)
Since pisaster starfish are the only thing in Makah bay that can eat California mussels, they are absolutely essential to the ecosystem of Makah bay. If all the pisasters disappeared somehow, mussels would completely take over the bay: they live up to 20 years and nothing can eat them. Every rocky spot would be completely covered in mussels and there would be no room for anenomes or clams or seaweed or anything else, and no food for any other animals.
So in the Pacific Northwest, pisaster starfish are a keystone species in tide pools and intertidal zones. They keep mussels from completely taking over everything.
Further south, in California, a different species is the keystone that keeps mussels under control: sea otters. They use tools to eat mussels. Instead of trying to get the shell open, they just use their hands to hit mussels with rocks and break the shells. Here's a video of a sea otter smashing a mussel with a rock:
Here's Robert Paine's paper, proposing the concept of a keystone species, using pisaster starfish and california mussels as an example:
Paine, R.T. (1969). A Note on Trophic Complexity and Community Stability. The American Naturalist 103 (929): 91–93.