hades


The HADAL ZONE: Life in the TRENCHES


Prof. Paul H. Yancey, Whitman College

Photos by Paul Yancey unless otherwise indicated, all copyrighted: please email for permission to use
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deepest fish
Deepest-Living Fish discovered on our Mariana Trench SOI expedition, Nov.-Dec. 2014
Old and new hadal submersibles
The manned bathyscaphe Trieste which reached the Mariana Trench bottom in 1960 (now in the Naval Museum in D.C.)
trieste
Unmanned HROV Nereus, which reached that same site in 2009 and used in our 2014 HADES expedition, Kermadec Trench.
Sadly,
Nereus is gone.
nereus
Hadal lander from U. Aberdeen -- HADEEP, HADES programs.
(click picture for details)
lander h
Kermadec Trench (blue region)
kermadec

Mariana Trench
mariana profile
.
(Above: from NOAA; Below: from Wikimedia)
mariana map

The Deepest Ocean Habitat--The Hadal Zone--is found in the deep troughs and trenches which go from 6000m to 11,000m max in the Mariana Trench. 'Hadal' is derived from Hades (the Greek word for the Underworld for dead souls and its god]. These habitats have the highest ocean pressures, are eternally just above freezing and without sunlight (which disappears completely by a mere 1,000 m / 3,300 ft), and may be very variable in food supply. They are the least explored habitat on earth (other than the subsurface biosphere), and we know more about the topography of the Moon and Mars than we do about the trenches!

Worldwide there are about 15 tectonic subduction trenches with hadal depths (see MAP on our HADES website), and several deep non-subduction troughs. These had been little explored since the 1950s, when the Soviet Vityaz (or Vitjaz) and the Danish Galathea 2 ships were used with nets and dredges to bring up animals from numerous trenches. However, nets have many problems, including: they are blind 'shots in the dark (you cannot target what you want)'; they let smaller and fast organisms escape; they destroy community structure; and they often destroy gelatinous animals. A bathyscaphe, the Trieste (see picture, right) manned by Jacques Piccard and Don Walsh, reached the very deepest ocean (Challenger Deep of the Mariana Trench, almost 36,000 ft / 11,000 m) in 1960, but no significant science was done as their window began cracking, so they ascended soon after reaching the bottom.

Trenches have been receiving renewed attention with advances in high-pressure technology: The Japanese ROV Kaiko was used in the Japan and Mariana Trenches in the 1990s; new baited camera/trap landers have been deployed since 2008 by University of Aberdeen (see pictures, right) and Scripps Inst. Oceanogr.; the Nereus hROV (see picture, right; unmanned sub, now lost) from Woods Hole Oceanogr. Inst. was used in the Mariana (2009) and our HADES program, 2014, in Kermadec Trench; and James Cameron's DEEPSEA CHALLENGER manned sub reached the Mariana Trench bottom in 2012. All these recent programs have yielded news-making results (see NEWS page and search for "trench".).

MOST RECENTLY, OUR GROUP HAS COMPLETED THE FIRST DETAILED EXPLORATION OF THE MARIANA TRENCH using SOI, U. Aberdeen (spectacular videos HERE) and U. Hawai'i landers;
including the WORLD'S DEEPEST FISH (yet).

Other HADES program equipment

BELOW: SOI hadal elevator landers, on which instruments can be placed (e.g., by an ROV, to run an experiment 1 or more days).
Left: has water sampling Niskin bottle and rock grabbers.
Right:
has coring respirometers
rg soi .CR lander
BELOW: Deep-sea baited animal/fish trap (U. Hawaii)
FT

AMPHIPODS: The dominant mobile animals at the greatest hadal depths! nightmare
Above: Enormous numbers caught at 8000 m
amphi eat
Above: H. dubia amphipods eating a larger amphipod (from 8000m). Most amphipods are scavengers, eating dead organisms that sink to the deep-sea floor. At this depth and below, there appear to be no predatory fish to keep amphipod populations in check. Perhaps as a result, amphipods also eat other amphipods, even becoming cannibals (where one eats its own species)!
There are also predatory Princalexia amphipods and SUPERGIANTS! See below
WHAT LIVES IN THIS EXTREME HABITAT?
Microbes and animals!





At the greatest depths, pressure-tolerant bacteria & archaea thrive (more on this HERE). Sea cucumbers such as sea pigs, various worm phyla, anemones, and amphipods (see photos, left; familiar to many people as tiny beach fleas) and the related isopods (familiar as terrestrial pill bugs or rolly pollies) dominate the larger fauna on or above the seafloor. Giant single-celled foraminifera called xenophyophores are common in some areas. Foraminifera in shallow waters have CaCO3 (limestone) shells, but these dissolve at high pressure; so xenophyphores make odd shells out of materials from the local environment.
There are also tiny animals in the sediment called meiofauna.

Curiously, many common marine groups including decapods (e.g., shrimp, crabs) and fish are absent from the greatest depths, about 8,500-11,000 m. Also most mollusc groups are absent, in part because CaCO3 shells dissolve under high pressure (some snails are found in the hadal zone, but their shells are like paper). But even unshelled molluscs--squids, octopods--are missing at the greatest depths.
MORE ON FISH: sharks and their relatives (cartilagious fish) have not been found below about 4000 m; but bony fish go deeper.
The 1960 Trieste aquanauts, at 11,000 m in the Mariana Trench, reported seeing a flatfish swim by; however, as no other flatfish have been found below 2,000 m anywhere in the world, and as no fish of any kind have been found below 8400 m anywhere else, most biologist believe that they saw a swimming flat sea cucumber such as Benthodytes, or the “flattened-cushion shaped” Galatheathuria aspera, which is white, oval, and about a foot long. We have written a detailed article debunking the Trieste "flatfish."
We have also published evidence suggesting that fish may not be able go below about 8000-8500 m due to biochemical limitations. Read more on this and fish pressure adaptations HERE, and our 2014 discovery of the world's deepest fish yet.

SEE ALSO: Hadal trenches: the ecology of the deepest places on Earth. A J Jamieson, T Fujii, D J Mayor, M Solan, I G Priede.
Trends in Ecology & Evolution 2009; 25:190-7. DOI:10.1016/j.tree.2009.09.009

BELOW: Some of the animals that we caught in 2014 in A. Kermadec Trench, and B. Mariana Trench:

A. Kermadec Trench 2014 HADES expedition (on the Thompson with Nereus): bathyal zone @1500m, abyssal zone @4000-5000m and hadal zone @6000-10,000m
 
BATHYAL (1500 m) & ABYSSAL AMPHIPODS we caught 4000-5000m
HADAL AMPHIPODS we caught (6000 - 10,000m)
amphi 1500
amphi 4k
075074blind
supergiantsg2
dubia
alexia
schell
.
Amphipod from 1500m
Note orange 'eyepatch'
Amphipod from 4000m
Compare the odd orange 'eyepatch' to that of the 1500m species
Amphipods from 5000m
Again, notice the orange 'eyepatches' and a blind species
SUPERGIANT amphipod (Alicella gigantea),
from 7000m. Read more about its capture in 2011 here; see a bigger one from the Mariana Trench below
Left: Hirondellea dubia found 7000-10,000m; predatory Princalexia amphipod from 8100m (named by Galathea scientists after Prince Alex of Denmark)
Right
:
Scopelocheirus schellenbergi
9000m; blind species that rolls into a ball when disturbed
Kermadec Trench continued
BATHYAL (1500 m) and ABYSSAL FISH caught (4000-5000m)
HADAL FISH caught (6200 - 7500m)
eel
.yaq
pachy
speccusk head
snailfish b.nk c.snailfish a
A synaphobranchid eel Diastobranchus from 1500m
See a video of viscious feeding: Click here then select "Eat or be Eaten"!
A ratttail or grenadier, Coryphaenoides yaquinae,
From 4000 m. Rattails are perhaps the most common abyssal fishes.
A zoarcid eel, Pachycara sp.,
from 4000, 5000 m.
Cuskeel Spectrunculus sp.
From 4000, 5000 m. Cuskeels are one of the deepest-living fish groups. Our expedition (thanks to Alan Jamieson) discovered a wild vacuum-hose mode of feeding. Click here for video: select "Grabbing a Quick Bite"

The gelatinous transparent Kermadec snailfish Notoliparis kermadecensis from 6500, 7500 m, deepest known fish in the Southern Hemisphere! See picture of live one (and link) at the far upper right of this page. Our analysis suggests it cannot live below about 8000m.
Kermadec Trench continued
HADAL ANEMONE
HADAL DECAPOD
HADAL CRINOID
HADAL HOLOTHURIANS (SEA PIGS / SEA CUCUMBERS)
anemone 7km
bigred
crinoid
cuc230
cuc247..cuc267
Tube anemone from 7000 m
Shrimp Benthesicymus crenatus 6500m. Read about the 2008 hadal discovery of these here.
Sea lily (crinoid) from 7000m
Sea pig from 7000m
Sea pigs / sea cucumbers from 8000m
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B. MARIANA Trench 2014 HADES expedition (on the Falkor) from abyssal zone at 4500-5000 m and hadal zone 6000-10,600 m
CLICK HERE to see UNIV. ABERDEEN'S VIDEOS of ANIMALS in the Trench including a depth transect!
 
EPIPELAGIC Fish
EPIPELAGIC Cnidarian
HADAL Cnidaria
ABYSSAL SPONGE
HADAL AMPHIPODS caught (6000 - 10,500m)
HADAL DECAPOD, MYSID
flying fish
manOwar
jelly jetson
glass sponge
rolly
bait
benthesicymus
mysid
Flying fish that landed on deck in a storm
Portuguese Man O'War caught on the fish trap lander at the surface
Hadal Jelly; SOI video frame from 7900m
Glass sponge, 5000m:
base+broken stalk on volcanic rock
Predatory Princalexia amphipod from 8220m (named by Galathea scientists after Prince Alex of Denmark)
Blind species, 9000m, that rolls into a ball when disturbed
Mackerel bait after amphipod attack; on lander 10,5000m
Top: Shrimp Benthesicymus, 6000m. Read about the 2008 hadal discovery of these here.
Bottom: Mysid from
7500m
MARIANA Trench continued
ABYSSAL AMPHIPODS caught 5000 m
More HADAL AMPHIPODS caught (6000 - 10,500m)
amphi close.bloated pod
superG paul.superG 1.superG mouth.superG eggs?
amphi 9km
sirena amphi
Amphipods from 5000m
Notice the orange/yellow 'eyepatches'
More amphipods from 5000m
Normally the bait in our traps is inside mesh bags so they cannot eat it. The bloated one on the right was from a trap with accessible bait

SUPERGIANT amphipod (Alicella gigantea), from 6000 - 7000 m.
Specimen on the right seems to be carrying eggs, but we are not sure. [Later we caught a supergiant at 5000m, the shallowest yet seen in a trench.]
Read more about its capture in 2011 here.
Swarms caught at 7.9km where there are few fish to eat them
Amphipod from 9000m
Sirena Deep amphipods, 10,500m, 2nd deepest place in the oceans
MARIANA Trench continued
ABYSSAL FISH (5000m) caught and/or filmed
HADAL FISH (7000 - 8145m) caught and/or filmed
rattail b
rattail b
thom rattail
new snailfish 1.new snailfish 1b.egg
new snailfish 5 .new snailfish 6
A ratttail or grenadier, Coryphaenoides yaquinae, 5000m
A ratttail or grenadier, Coryphaenoides spp, 5000m
Lander cam photo of rattail, 5000m
Photo credit: Thomas Linley

The 1st of TWO NEW species of snailfish we discovered in the Mariana Trench; this one from 7500m. Both have transparent skins, so you can see organs inside (e.g., liver, brain). Last photo is a snailfish egg

The 2nd new species of snailfish -- made news media worldwide; currently the deepest known fish in the oceans at 8145m.
These are frame grabs from an SOI lander video at 7900m

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