The Plankton Chronicles Project is my new obsession. Full stop. In this microscopic series, research director Christian Sardet and his team explore the beauty and diversity of plankton (the tiny organisms adrift in our oceans).
The film Sea Urchins - Planktonic Origins (viewable at the end of the slideshow below) highlights the incredible stages of an urchin's development as it moves from egg to adult.
The short is just one of many episodes in the series, which covers everything from jellyfish to crabs. (Protip: don't let the Twilight Zone-esque voiceovers keep you from watching the rest ... because, sweet mother of Darwin, they are exquisite). This is one metamorphosis you don't want to miss.
So, how do you make a sea urchin? Just like in humans, it all starts with an egg ... but in this case millions of them are released into the water column. This reproduction strategy is called broadcast spawning.
1 1 Millions of eggs
A male urchin will release his sperm into the water column from one of five hidden gonads. Most urchins are either male or female, but interestingly (though extremely rare) hermaphroditic urchins turn up from time to time. During a 25-year study of one species (Arbacia punctulata) only six hermaphrodites were found.
2 2 A shot of spermDuring broadcast spawning the surrounding waters often become cloudy with tiny gametes. Fertilisation occurs when the sperm and eggs find their way to each other in the open ocean.
It takes between 12 and 24 hours for a human cell to divide once ... but urchin reproduction happens in hyperdrive mode. Within six hours, the developing urchin egg will already have 32 cells!
4 4 Divide and conquerAfter 20 hours, the will-be urchin becomes a hollow sphere of 128 cells known as a blastula.
The blastula gives rise to the urchin’s iridescent larval form, called a pluteus (which, to my delight, looks exactly like a tiny rocket ship). This free-swimming pluteus larva will feed on phytoplankton for five to eight weeks as it continues to grow.
Drifting along in the water column is not the safest way to get around. Reproducing in such high numbers ensures that at least some pluteus larva will survive to adulthood. Their delicate structures are made of calcium carbonate.
7 7 Strength in numbersAfter weeks of sucking down phytoplankton, the eight-armed pluteus begins to show adult features internally. Just a few days later, spines and tube feet start to make their way to the surface!
8 8 MetamorphosisMetamorphosis is complete within a week and shortly thereafter the little juvenile will be moseying along on the seafloor.
9 9 Baby urchinThough the ocean is not a thick plankton soup, it is full of microscopic life. So think about these tiny urchins the next time you accidentally swallow some seawater (nom nom!).
10 10 PerspectiveSo, how do you make a sea urchin? Just like in humans, it all starts with an egg ... but in this case millions of them are released into the water column. This reproduction strategy is called broadcast spawning.
1 Millions of eggs
A male urchin will release his sperm into the water column from one of five hidden gonads. Most urchins are either male or female, but interestingly (though extremely rare) hermaphroditic urchins turn up from time to time. During a 25-year study of one species (Arbacia punctulata) only six hermaphrodites were found.
2 A shot of spermDuring broadcast spawning the surrounding waters often become cloudy with tiny gametes. Fertilisation occurs when the sperm and eggs find their way to each other in the open ocean.
It takes between 12 and 24 hours for a human cell to divide once ... but urchin reproduction happens in hyperdrive mode. Within six hours, the developing urchin egg will already have 32 cells!
4 Divide and conquerAfter 20 hours, the will-be urchin becomes a hollow sphere of 128 cells known as a blastula.
The blastula gives rise to the urchin’s iridescent larval form, called a pluteus (which, to my delight, looks exactly like a tiny rocket ship). This free-swimming pluteus larva will feed on phytoplankton for five to eight weeks as it continues to grow.
Drifting along in the water column is not the safest way to get around. Reproducing in such high numbers ensures that at least some pluteus larva will survive to adulthood. Their delicate structures are made of calcium carbonate.
7 Strength in numbersAfter weeks of sucking down phytoplankton, the eight-armed pluteus begins to show adult features internally. Just a few days later, spines and tube feet start to make their way to the surface!
8 MetamorphosisMetamorphosis is complete within a week and shortly thereafter the little juvenile will be moseying along on the seafloor.
9 Baby urchinThough the ocean is not a thick plankton soup, it is full of microscopic life. So think about these tiny urchins the next time you accidentally swallow some seawater (nom nom!).
10 PerspectiveAll images: Christian Sardet/screengrab from Vimeo