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My book "Ask An Ocean Explorer"(*) is out in 30 days (on 21 Feb).

So for the next 30 days, I'll be sharing some of the wonders & history of exploring the deep here, in #30daysofdeep

(*<cough>available for pre-order, e.g. amazon.co.uk/Ask-Ocean-Expl…; also for Kindle, & audio book)
On this day, 59 years ago, two people reached the ocean's deepest point for the first time.

Here's a wonderful account by one of them, Don Walsh, in his own words: scientificamerican.com/article/diving…

And here's some archive newsreel footage:

#30daysofdeep 1/30
#30daysofdeep 2/30

Here's Gorringe Bank, a twin-peaked seamount near Portugal that rises from ~5 km deep to ~50 m deep, taller than Mont Blanc in the Alps. Home to >800 species, from deep-sea glass sponges to kelp.

Discovered by USS Gettysburg in 1875 under Capt Henry Gorringe.
#30daysofdeep 3/30

Meet Rimicaris hybisae: shrimp that thrive at undersea hot springs 5 km (3.1 miles) deep in the Cayman Trough.

The species was discovered during a @NERCscience expedition in 2010, & described by Dr Verity Nye during her PhD research: doi.org/10.1017/S00253…
#30daysofdeep 4/30

What eats those shrimp? Here's Pachycara caribbaeum, an eelpout fish (mapress.com/j/zt/article/v…); a microCT scan shows the shrimp in its gut.

While adults bask at balmy deep-sea vents, juveniles live where bizarre blocks of methane ice poke out of the seabed.
#30daysofdeep 5/30

Some record-setting dives:

923m Beebe & Barton 1934
1372m Barton 1949
3167m Piccard & Piccard 1953
4050m Houot & Willm 1954
10916m Piccard & Walsh 1960
#30daysofdeep 6/30

On this day 10 years ago, we got our first glimpse of "Hoff" crabs at deep-sea vents in the Southern Ocean, towing a camera 2.4 km deep from RRS James Clark Ross.

It turned out they had been photographed before, but ignored, in 1966 - journals.plos.org/plosbiology/ar…
#30daysofdeep 7/30

In 1858, the first seafloor telegraph cable across the Atlantic could carry ~10-12 words per minute.

160 years later, the latest fibreoptic cable across the Atlantic ocean floor can live-stream 71 million HD movies simultaneously:
#30daysofdeep 8/30

Remember the leaping mobula rays of #BluePlanet2 & other TV documentaries (e.g. )?

Here's a mention of the behaviour in C. S. Forester's "Hornblower" novel "The Happy Return" (aka "Beat To Quarters" in the US), published in 1937:
#30daysofdeep 9/30

Seawater blocks the radar signals satellites use to make detailed maps of the surfaces of other planets.

For detailed ocean floor maps, we have to use sonar from ships & underwater vehicles.

Here's how our ocean floor maps compare with maps of other planets:
#30daysofdeep 10/30

Autonomous Underwater Vehicles (AUVs) help with the initial "make a map" step of ocean exploration, enabling better use of human-directed vehicles for the "investigate the anomalies" step

Here's Autosub6000 being launched & recovered:
#30daysofdeep 11/30

Deepest breath-hold dive no fins or weights: 102 m (Trubridge, 2016)

Deepest breath-hold dive: 253 m (Nitsch, 2012)

Deepest scuba dive: 332 m (Gabr, 2014)

Deepest ambient-pressure dive in the ocean: 534 m (COMEX Hydra 8 team, 1988)

#30daysofdeep 12/30

Finding a mate in the dark & often sparsely populated depths can be a challenge.

The tracks of Paroriza pallens sea cucumbers reveal their not-so-brief-encounters on the ocean floor, when two meet & then travel on together side-by-side (pic: @oceanexplorer).
#30daysofdeep 13/20

1st female bathynaut: Gloria Hollister (1934)

1st female bathynaut in DSV Alvin: Dr Ruth Turner (1971)

1st female pilot-in-command of DSV Alvin: Prof Cindy Van Dover (1990)

#30daysofdeep 14/30

165 years after the Mid-Atlantic Ridge was 1st glimpsed on Maury's seafloor map of 1854: UK, Brazil, Portugal claim areas as territory around their islands, & Russia, France, Poland have mining exploration licences there.

(Map from advances.sciencemag.org/content/4/7/ea…)
#30daysofdeep 15/30

Are "sea monsters" real? Here's a round-up of ocean giants, from oarfish to Giant Squid, by @DrCraigMc & colleagues: peerj.com/articles/715/

And here's a classic paper estimating no. of undiscovered large species, by @CharlesPaxton4: cambridge.org/core/journals/…
#30daysofdeep 16/30

Some deep-sea animals do resemble sci-fi aliens (or perhaps it's the other way round); here's Phronima, an amphipod crustacean that makes its home inside a salp: theconversation.com/meet-phronima-…

(& for a few more sci-fi/deep-sea matches, see joncopley.com/blog_nov17a.ht…)
#30daysofdeep 17/30

"Zombie" worms burrow into the skeletons of dead animals on the seafloor, digesting their bones with acid (royalsocietypublishing.org/doi/full/10.10…) to make a living from them.

Here are some on a whale skeleton we found 1.4 km deep in the Antarctic (sciencedirect.com/science/articl…):
#30daysofdeep 18/30

Our waste unfortunately ends up in the deep ocean too; here's some rubbish we found 2.3 km deep.

The CO2 molecules that we pour into the atmosphere affect the ocean depths as well, e.g. changing how some minerals dissolve in the deep: pnas.org/content/115/46…
#30daysofdeep 19/30

Marine biologists have watched the same female deep-sea octopus (Graneledone boreopacifica) keep vigil over her developing eggs at 1.4 km deep for 4.5 years - the longest egg-brooding period of any animal: mbari.org/deep-sea-octop…

(& journals.plos.org/plosone/articl…)
#30daysofdeep 20/30

For #WomenInScienceDay, meet Marie Tharp, who discovered the vast undersea volcanic rift that forms the geological backbone of our planet - a discovery as profound for Earth sciences as the structure of DNA in biology:
#30daysofdeep 21/30

Hydrothermal vents & cold seeps are "island-like" habitats on the ocean floor, so for #DarwinDay, here's how species of "yeti" crabs have evolved among vents & seeps - a modern take on Darwin's finches, revealed by @Elpipster:
#30daysofdeep 22/30

On 22 Sept 1932, William Beebe & Otis Barton broadcast live on NBC & BBC radio from their bathysphere at a then-record depth of 671 metres - #WorldRadioDay

Sadly the 1st broadcast from the deep was not recorded (but was transcribed): blogs.loc.gov/now-see-hear/2…
#30daysofdeep 23/30


Roses are red
But because most bioluminesence in the deep ocean is blue-green
They appear black to most deep-sea animals
#30daysofdeep 24/30

While astronauts were heading to the Moon aboard Apollo 11 in July 1969, six bathynauts spent 30 days aboard the "mesoscaphe" Ben Franklin, diving down to >500 m deep while drifting >2000 km in the Gulf Stream:
#30daysofdeep 25/30

Today is #WorldWhaleDay & here's evidence that some might dive deeper in ocean than we imagined -- maybe beyond 4 km deep -- pieced together in a recent paper by @Leigh_Marsh @VeerleHuvenne @DanielOBJones:


#30daysofdeep 26/30

Although Piccard & Walsh reported seeing a flatfish at the ocean's deepest point, the deepest confirmed observation is a snailfish, filmed 8178 m deep:

Biochemistry may prevent fish going much deeper than that:
#30daysofdeep 27/30

Most deep-sea animals don't "explode" if brought to the surface; their bodies are solid tissues & liquid (no gas inside them), which doesn't expand with lower pressure.

(Take a syringe of water & seal the hole with your thumb; you can't pull the plunger out)
#30daysofdeep 28/30

A network of >4000 robotic drifters now gives us a large-scale, real-time map of conditions in the oceans & how they are changing...

...including measurements of how the oceans absorb heat trapped in the atmosphere by CO2 emissions:

#30daysofdeep 29/30

Before oceanographers could map ocean features far from land, cartographers embellished ocean spaces of maps with sea monsters, often based on tales of mariners.

Olaus Magnus's "Carta Marina" of 1539 has some lovely examples:
#30daysofdeep 30/30

Today's the day: "Ask an Ocean Explorer" is out!

Hopefully this thread has given a flavour of its pottage of the history of ocean exploration, inhabitants of the abyss, undersea technology, and how our lives are connected to the hidden face of our planet.
I'm hugely grateful to the skill & patience of my editor @Gowlettronic, and all of the team at @HodderNonFic, for bringing the book into existence :)

Looking forward to talking about exploring the oceans at upcoming literary festivals, thanks to @BeccaCMundy & the publicity team
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