from Wiktionary, Creative Commons Attribution/Share-Alike License.
- phrase Third-person singular simple present indicative form of
there be. Used to indicate the existence of something physical or abstract in a particular place. see also there are.
Sorry, no etymologies found.
As far as I remember in Karl Zimmer´s book "At the Water's Edge: Fish with Fingers, Whales with Legs, and How Life Came Ashore but Then Went Back to Sea" there is a notion about the flukes.