engorged with nutrition
her exquisite pearls
Isn’t it amazing, how an egg the size of a pinhead turns into a 2 m long, 200 lb armored giant that wanders meandering rivers for 100 years or more? Sturgeon eggs are tiny but like all fish eggs they are mighty – after all, they contain all the building blocks and tools to make real life fish!
Eggs are filled with maternal DNA of course and also vitamins, metals (to kick-start chemical reactions), hormones, carotenoids (antioxidant power), calcium (for bone growth) and energy sources (e.g. proteins and fats). After fertilization all of these goodies are used to transform the dewy globe into a young fry.
But how does all that stuff get in the egg?
Most items are likely taken up into the developing egg during vitellogenesis. This egg-srtaordinary (ha!) process involves a special protein called vitellogenin being shuttled from the liver into the developing egg. Vitamins, metals, hormones, carotenoids and calcium are thought to be hitching a ride on vitellogenin as it is engulfed into the egg. Once in the egg, vitellogenin is broken down into smaller fat-protein hybrids that will form the nutritious yolk developing fish “consume” and turn into eyes, a body and fins.
P.S. Why are salmon eggs bright orange and sturgeon eggs black? One hypothesis is mom’s diet – in the ocean salmon eat lots of krill which have lots of red-pigment carotenoids that can get deposited into eggs; sturgeon are bottom-feeders vacuuming up worms and snails which are low in red-pigment carotenoids.