Triploid (a.k.a “single-seed”) Oysters for Dummies

I am learning A LOT about oysters, and I thought I’d change up the blog and post some of my new knowledge. I switched to a contemporary theme (gave up on my own slow-loading responsive design) and switched to a generic one. If you want to see my new graphic design work, just check out But, today we’ll be talking about a sudden interest of mine, the industry standard, triploid oysters.

the more man interferes with nature the greater become the problems he creates

~Sir Maurice Yonge (1899-1986)

Humans have two sets of chromosomes, AKA Diploid (is that where the musician Diplo gets his name? –probably not). Chromosomes are those cool looking double helices that we think of when we think of DNA. As you probably know, they are used to make sure that cells are accurately copied. Almost all species are the agile dual-chromosome welding “diploid” class. Oysters normally are too, but humans have genetically engineered them to have three sets. Those genetically engineered species are called “triploid oysters” and a surprising amount of oysters farmed today are of this variety.

“the very essence of sex is meiotic recombination.”


In a process called meiosis germ cells (AKA egg and sperm) combine their two sets of chromosomes to one set. Diploids can do this just fine. Triploids can’t. I was trying to figure out why and found this rather technical explanation:

The addition of one or more extra chromosomes is nearly always deleterious because the proportions of genes in those extra chromosomes are altered[…] The deleterious effect can be expressed at the level of gametes, making them nonfunctional, or at the level of the zygote, resulting in lethality, sterility, or lowered fitness.


In humans it’s a really dangerous genetic mutation that usually leads to death (miscarriage). In most farmed bananas, seedless watermelons, or in our case single-seed oysters, it means they aren’t focused on reproduction. As a result the extra energy normally used for reproduction is (usually) used for growth. Since oysters reproduce in warmer weather, it also means you don’t have that creamy egg-y summer oyster. They are called “single-seed” because they don’t reproduce. Like many agricultural crops grown on an industrial scale.

I have been informed by Mr. Funabiki that there is also a temperature control mechanism that helps to determine the sex of the oyster (yes, there are male and female oysters). How that works is a post for another time.

You can buy the lab grown seeds if you want. None of the oysters that Funabiki Shoten purchases from its farmers are triploid. Our farmers seeds are produced the old fashioned way in Hiroshima. That may also be a nice subject for a post in the future. In the meantime, for clear business reasons, these year-round oysters are gaining popularity.

The culture in Japan, is another story. This year warmer winter “Indian summer” (小春日和) temperatures and high vegetable prices mean less hot-pots for dinner, and as a result oyster market prices are slightly down. But marketing is already changing the culture. Oyster Bars, once practically unheard of, are now a popular night-life attraction in most major cities–and feature many western style oyster dishes. Time will tell if it becomes a mainstay in Japanese future culture. But, for now anyway, my curiosity about triploids has been satiated.


Tasty Mutants: The Invention of the Modern Oyster

Molluscan Aquaculture and the Triploid Oyster

Quick Lesson in Genetics

Polyploidy in Plants & Animals: Speciation & Cells

Oyster Season

Oyster Season is a blur. The chilly days flow by with chunks of ice in them, but the people are warm. The air evaporates the water from ones eyes and leaves a burning salinity–it helps to keep eye drops on hand. But the oysters are beautiful. They just get bigger and fatter, like little white pillows, as the winter presses on.

We haven’t taken many trips out to Sakoshi since the season has started, but the oysters we’re getting are great. Almost at their peak size now–taking two bites to really savor.

We’ve been to three amazing diners. Two in Kobe, at Spontaneous and Kitano Hotel; and one in Kyoto, at Mavo. I posted about Spontaneous already for Junko’s birthday. You can also see a few photos from Kitano Hotel and Mavo here. We also took a trip to Nagoya where Toro Y Moi (the whole band) had some of our oysters. Andy, the drummer, was my first best friend. I remember hanging out with him in Montessori school in Columbia, South Carolina pretty well. Also made three beers, an Imperial Pilsner called “Mabudachi” (with friends Mohi, Andrew, and Ben in addition to Junko and myself), a post wedding oyster IPA (just Junko and I using hops from Brodie and Amanda), and we currently have an Session IPA (yet to be named, but brewed with Ben Enman, so JCB something?) in secondary with dry hops.

Anyway, it’s time to get back to work.

Oyster Season 2015-2016