Living cells that make their living inside other living cells

Inside the membrane of most of your cells are what look like little cells, with their own membranes and DNA. These little cell like things do important things, without which your cells couldn’t function, and you couldn’t live. The thing is, once upon a time, they really were cells in their own right, cells that one day moved inside of another cell, and never left.

Here are a couple of videos on the pearl fish and how it lives inside a sea cucumber.

Pearlfish hides inside a sea cucumber

Seeking shelter up a sea cucumber's bottom

Here’s a video about cleaner fish.

coral reef: cleaner fish; remora

Here’s an article about African buffalo, and the birds that help keep them clean.

Making New Friends: African Buffalos get all the birds

Here’s a video about several birds that have partnered symbiotically with other creatures.

Animal partnerships - David Attenborough

Here’s an article about the origin and evolution of Chloroplasts, which do photosynthesis for most modern plants.

Chloroplast evolution, structure and functions

Here’s an article comparing Chloroplast, which moved into other cells over a billion years ago, to roughly the same thing happening again, much later, only 60-millean years ago.

Small Things Considered: Play It Again, Cyan

And here are a couple of articles about the origin and evolution of mitochondria.

Origin of Mitochondria

The origin and early evolution of mitochondria