Poor Richard’s Almanac

Anybody out there know anything about the sex life of shrimp? Our friend Ben is referring to aquarium shrimp, and most specifically to the type of algae-eating shrimp known as Amano shrimp because they’re used in the fabulous aquascapes of the legendary Japanese aquarium master Takashi Amano to control algae in the tanks.

I ask because I happen to have five Amano shrimp in my larger aquarium, though I didn’t realize it until the other day. I thought I had four Amano shrimp and one much larger shrimp, type unknown. Then suddenly our friend Ben saw all four Amano shrimp literally crawling all over the larger shrimp, and I realized that I in fact had five Amano shrimp, four males and one female. 

I concluded that the female had reached sexual maturity, somehow signalled this to the males, and they had responded by rushing over and doing their best to fertilize her eggs. Having never seen shrimp mating before, our friend Ben was a bit bemused by what was going on. My guess is that the males’ swarming behavior in some way stimulated the female to lay the eggs, and that they ejected their sperm into the waters around her to fertilize them, much like fish or frogs.

But, ahem, I really don’t know. Things in the tank seemed to return to normal after the one day of sex-crazed madness, but then today, I saw that the female shrimp seemed to be carrying something in her many legs. “Cradling it” would have been more descriptively accurate. Was it an egg mass, and is that what shrimp do with them, rather than attaching them to aquatic plants or the glass of the aquarium or leaving them to float free in the water? Was it instead a hatchling she was protecting?

Naturally, our friend Ben would love it if little shrimp materialized and survived infancy so I could tranfer them to my small aquarium and, perhaps, the greenhouse water garden. But I really don’t have a clue what’s going on. If you do, please enlighten me!