Linda Bower has produced one of her finest water macro videos, matching action with music in a way that Beethoven would be proud of. This one is of the larvae of a predaceous diving beetle that seems built to feed on ostracods. For those of us unfamiliar with these species, this will take a lot of explaining. First I am taking this directly from our 2017 blog posting about ostracods in a fountain.
Ostracods, a.k.a. seed shrimp, are tiny crustaceans that live in water. They are an ancient species with 70,000 species identified but "only" 13,000 that have survived extinction. They are common in fresh water, frequently in temporary pools and ponds. Their eggs resist dehydration and can wait for months or many years before hatching with their next hydration.
|Click to enlarge - Pionocypris vidua, - bumblebee.org|
Their flattened bodies lie within a bivalve structure similar to a mollusc. They swim with their legs extended but can contract them and close their "shell" to protect themselves. They lack a distinct abdomen and circulatory system but have antennae to seek out food (diatoms, bacteria and detritus) and mandibles and maxilla to obtain it. I will leave the anatomical details to Wikipedia.
Here are what 5th grade WOLF students would call "Fun Facts"* although some might be R-rated.
- Although fish eat ostracods, some may survive the passage through the gut. One study showed that 26% of those eaten by a bluegill passed out the rectum alive. Who counts these things?
- Many species reproduce parthenogenetically, i.e. without male fertilization, but some species have the largest sperm in the animal kingdom, up to 3.6 times longer that the adult's body.
- Ostracods are the most abundantly preserved arthropod in the fossil record (500 million years) and boast the oldest known example of a fossilized penis, 425 million years ago.
- Some species are bioluminescent, a defense mechanism seen in this video. During WWII, Japanese troops collected and dried specimens, then rehydrated them to provide a dim light for map reading without giving away their location.
|Desmopachria beetle larva|
|Desmopachria dispersa - Mike Quinn CC|
Her video features guest appearances by flatworms (they look blue under the LED lights) and a Nematode in the last clip. For the big show you are now ready to see Desmopachria and the Ostracods!
Much more on fascinating ostracods 30 Interesting Ostracod Facts.
* For more details on Desmopachria, download Water Beetles of Florida 5.53 This is a large comprehensive PDF. For the Desmopachria basics, see this page 5.53.
Photographs are taken from Linda Bower's video.