Finally, Some Good News About Corals | SciShow News

[♪ INTRO] Corals often pop up in the news and, usually
not for good reasons. Especially if the word “bleaching” is
also in the headline. But there might finally be some good news
for corals on the horizon. A study published last week in the journal
Genome Biology suggests that some corals have the ability to make a nutrient most animals can’t, and that could mean they’re
more resistant to bleaching. The goal of the paper was actually to find
differences between two big groups of corals: Robust corals like the brain or
mushroom varieties, and complex corals, which include big, branching types like staghorn coral. But, when the researchers compared the genomes
of four complex species and two robust species with those of closely related sea anemones,
they found something even more exciting. Hidden in the robust coral DNA was a recipe
for making histidine, an essential amino acid. Amino acids are the building blocks for proteins,
the molecules that make up most of a cell’s machinery and
act as structural support for tissues. Animals can make certain amino acids by themselves,
but certain ones, called essential amino acids, have to come from their diet. Or, in the case of corals, from their special
relationship with algae. See, most reef-building corals have algae
called zooxanthellae in their tissues that provide them with oxygen,
sugars, and amino acids. The coral, in turn, gives its algae the starting
materials it needs to make those things, like carbon dioxide, as well as
a nice, protective home. But like all relationships, things can sometimes
get a little rocky. If conditions get too physically stressful,
like if the surrounding water gets too warm or polluted, the corals
evict their algal partners. This is referred to as coral bleaching because
the algae give corals their color, so when they’re gone, the corals look bleached. Now, bleaching doesn’t immediately kill coral. Sometimes, they recover and bring in new algal
tenants. So being able to make histidine, instead of
having to get it from algae, could help robust corals cope with stress, as it might let them
last a little longer without their algae friends. Now, other animals generally can’t make
histidine, but algae, fungi and bacteria all can, so the researchers wondered if the corals got the genes
from one of them through horizontal gene transfer. But the histidine-making genes were scattered
all throughout the coral’s DNA and were broken up by non-coding sections, which means
the corals probably evolved the ability to make histidine on their own very early on. The complex species of coral then lost the
ability pretty soon after. Scientists also found that stress-tolerant corals had
larger numbers of a particular gene called HSP20. HSPs, or heat shock proteins, are found in
many organisms and help protect cells from damage. So these might explain the corals’
increased stress tolerance, but the authors caution that this can’t be
determined from genetic data alone. Still, these findings could help scientists
select tougher corals when trying to restore reefs. And they may suggest helpful ways to genetically
engineer corals to withstand the warmer, more acidic oceans we’re getting
thanks to climate change. In other survival-related news, biologists have
discovered that the fuzziness of certain moths may be a strategy to hide from predators,
specifically, bats. The bats that hunt moths see their prey in
the dark using echolocation, sending out high-pitched calls and listening to how those calls bounce
back to zero in on their targets. But in a talk at the Acoustical Society of
America’s 176th Meeting, held in Victoria, Canada this month, researchers suggested that this
moth’s fur can act as a kind of sound dampening device. Biologists call this acoustic camouflage.
I didn’t know this was a thing but that’s great! Basically, that fuzzy stuff, which is made
of modified chitin scales, not true hairs, makes the moths less echoey, so it’s harder
for the bats to find them. The researchers figured this out by comparing
the sounds reflected by two species of moths to two butterfly species which
aren’t normally bat food. They used a technique called acoustic tomography. In it, researchers send out ultrasound, pulses
of sound with frequencies above what we can hear, from a loudspeaker, then they measure
the echoes that bounce back using a microphone. By doing this from hundreds of angles, they
could use a computer to combine all of the echoes into, like, an image of the moth, kind
of like a sonogram. But when the scientists aimed ultrasounds at
the moths, most of them weren’t reflected back. The furry moths absorbed up to 85 percent
of the sound that hit them, compared to just
20 percent for the butterflies. This was largely because of the fur: when
the researchers removed the moths’ bristles by gently brushing them with a paintbrush,
their bodies reflected 38 percent more sound. Not all moths are super furry, though, and
there’s probably a reason for that. Some species have evolved ears that can hear
a bat’s hunting calls, allowing them to flee from their attackers, so they have less
need for sound-dampening fur. Discovering the acoustical qualities of moths
could help with more than just understanding moth evolution and ecology, or just my curiosity
about why moths are all fuzzy and cute. The researchers hope their discovery can inspire
new sound-dampening materials for headphones, homes, or studios like the one I’m standing
in right now, so we don’t have to be like “Oh my god! Stop walking around!” Thanks for watching, and thanks especially
to our President of Space, SR Foxley. We really appreciate your continued support, SR! If you want to be a President of Space like
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