So I’m not trying to make anyone feel inadequate,
or anything?
But scientists have uncovered fossil evidence
of an animal that produces sperm ten times
longer than its body.
The overachiever in question is a crustacean
called an ostracod, which is a type of tiny
freshwater shrimp.
Ostracods are still around today, and many
species seem to share this ability to create
enormous male sex cells.
A typical ostracod specimen is about a millimeter
long.
Its sperm?
Up to a centimeter.
Just to give you a sense of perspective: If
humans wanted to compete in this arena, an
adult human male’s sperm would need to be
about 36 meters long.
Scientists have known about this reproductive
oddity in ostracods for more than a hundred
years.
What we haven’t been able to figure out
is what the evolutionary origins are of these
giant sperm, and what function they might
serve.
On Wednesday, researchers in Germany said
that they’d found dozens of 16-million-year-old
fossil ostracods in an Australian cave, and
they were so well-preserved that the scientists
were able to see how the sperm was configured.
And they found these cells in both males,
before they were released, and in females,
after they’d been received.
Part of what they found was that the structure
of the sex cells was virtually identical to
those in ostracods living today.
As in modern specimens, the fossil sperm lacked
a flagellum, or tail.
Instead, they were rolled up like balls of
twine.
Once inside the female, the cells gradually
unravelled, turning into a big scrambled-up
spaghetti-pile of sperm.
Now, producing such massive sperm takes a
lot of energy -- up to a third of a male ostracod’s
body is dedicated to making and distributing
these cells.
But the weird thing is, scientists don’t
really have any idea what the point of it
is.
They conclude that, if this unusual reproductive
set-up has persisted for tens of millions
of years, then there must be something about
it that works very well for the ostracods.
We just don’t know what that something is.
Still, the scientist whose job it is to figure
out why tiny shrimp produce giant sperm must
have a really entertaining OK Cupid profile.
Now, on the topic of evolution and underwater
life, let’s talk about tentacles!
Up until last week, marine biologists believed
that one of the largest species of sea anemones
in the world was an animal known as B. daphneae,
with tentacles reaching up to two meters long.
But this week, thanks to DNA research led
by the American Museum of Natural History,
we know that it isn’t an anemone at all.
It just really, really looks like one.
It turns out it’s the first species ever
identified in an entirely new order of animal
life.
Okay, in taxonomy, your order is the rank
above your family, three ranks above your
species.
We humans are in the order of primates.
Cats and dogs and bears and raccoons and foxes
and skunks and and weasels are all in the
order of carnivores.
So finding a new order is a big deal.
So where’d this new order come from?
Well, for a long time, anemones have been
classified mostly based on obvious physical
characteristics -- or, more specifically,
the characteristics they lack.
Like, they don’t have bones, so they’re
not fish, and they don’t build colonies,
so they’re not corals.
But by analyzing the DNA of 112 different
anemone species, the biologists were able
to get a clearer sense of their evolutionary
relationships and reorganize their family
tree.
And one of the species they studied was B.
daphneae, which was only discovered in 2006
in the east Pacific, and seemed really, unusually
large for an anemone.
As it turns out, it is both genetically and
structurally something altogether completely
different.
The animal, given the new name Relicanthus
daphneae, is a beautiful example of convergent
evolution, which is when two life forms from
totally different evolutionary branches develop
the same traits independently.
In this case, with its long, brightly-colored,
stinging tentacles, R. daphneae looked and
acted just like an anemone.
But to quote the lead author of the new report:
“Putting these animals in the same group
would be like classifying worms and snakes
together because neither have legs.”
Anemones are still not very well understood,
and in fact life in the deep ocean is generally
not very well understood.
With entirely new orders of life still being
discovered, who knows what else we might find
down there?
I know how you can find out!
Keep watching SciShow.
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week.
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