In the dark of the ocean, some animals have evolved to use bioluminescence as a defense. In the animation above, an ostracod, one of the tiny crustaceans seen flitting near the top of the tank, has just been swallowed by a cardinal fish. When threatened, the ostracod ejects two chemicals, luciferin and luciferase, which, when combined, emit light. Because the glow would draw undesirable attention to the cardinal fish, it spits out the ostracod and the glowing liquid and flees. Check out the full video clip over at BBC News. Other crustaceans, including several species of shrimp, also spit out bioluminescent fluids defensively. (Image credit: BBC, source video; via @amyleerobinson)

ostracods are so neat i love them. favorite zooplankton a+

they’re like. little round baby clams that still have legs and swim around and nibble the algae. and bump into each other and interact like little fussy mice. and dig burrows in the silt like they each have their own tiny mud house. and are so small they look like little pink dots.

i have a bunch in a decrepit old tank outdoors and they each have four little spots on their shells. they are the size of sand grains, but they still managed to have little markings. and that’s fucking adorable.

the closest match i found for the lot i have is this fellow


Ostracods eject light when they’re threatened

The ostracod isn’t the big fish: It’s actually the petite crustacean firework the fish spits out! Ostracods send a bioluminescent protest off when threatened, which makes them rather unappetizing to eat. The two chemicals — luciferin and luciferase — glow when mixed

(Source 1, Source 2)


Fish filmed spitting ostracod ‘fireworks’

One of nature’s most dazzling underwater displays, bioluminescence, has been captured as a form of self-defence by a BBC film crew.  [BBC]

I had a dream that was pretty unremarkable except there where these “fairies” that kept getting trapped in old cobwebs on top of the refrigerator and I had to free them and shoo them out the house. They looked a lot like giant ostracods except they where about the size of ping pong balls and they flew using these four frilly feelers. They were white and sort of dull looking, but they had pretty eyes you could barely make out under their shell. 


This tiny crustacean called an Ostracod, is a shrimp-like organism about 1mm in size. When eaten by another fish, the Ostracod immediately releases a bioluminescent chemical in an attempt to illuminate the fish from the inside making it identifiable to predators.


I need them..

What you’re seeing is the defense mechanism of a tiny crustacean called an ostracod, a shrimp-like organism about 1mm in size that some fish accidentally eat while hunting for plankton. When eaten by a translucent cardinalfish, the ostracod immediately releases a bioluminescent chemical in an attempt toilluminate the fish from the inside, making it immediately identifiable to predators. WHAT. Not wanting to be eaten, the cardinalfish immediately spits out the ostracod, resulting in little underwater fish fireworks. What an incredible game of evolutionary cat and mouse.

I used to think these were tiny water bugs, but learned from fatchance that they’re actually crustaceans.  They come in a range of colors from greenish to fairly bright orange, and each one is the size of a medium grain of sand.  It is very odd to watch them go about their business, swimming purposefully from one place to the next and hanging out in little groups like this one.