Milly: Ugly Fish pt 8

Milly: Ugly Fish pt 1
Milly: Ugly Fish pt 2
Milly: Ugly Fish pt 3
Milly: Ugly Fish pt 4
Milly: Ugly Fish pt 5
Milly: Ugly Fish pt 6
Milly: Ugly Fish pt 7

Coming back to my post about pressure (pt 6), how are deep sea animals adapted to survive at depth?

As there are all sorts of animals currently inhabiting the deep, I'll concentrate on fish. Fish are the best anyway. Slightly biased.

Well the problem is, fish don't just have to cope with the crushing pressure (up to 800x greater than at the surface) but the deep is also very dark (beyond 1000m there is negligible surface light) and cold (2°C) making things such as moving around, finding food and reproducing much more challenging. Let's have a look at a few fish and see how they do it. Enter handsome fellow number one, the anglerfish.

Whipnose anglerfish, about the size of a football.
Note the long lure with the tiny esca on the end, capable of bioluminescing.
Image: Dianne Bray

A selection of anglers.
Image: Dr Theodore W. Pietsch and Christopher P. Kenaley

There are 11 families of deep sea anglerfish, some only containing one species, such as the lonely prickly seadevil, Centrophryne spinulosa (Centrophrynidae family) others have many more such as the footballfish, Himantolophidae with 19 species. They are a surprisingly diverse group of ugly fish. As you can see from the pictures above, these animals don't look particularly athletic. If you were to design an animal for a race underwater I doubt 'round' would be the shape you would go for. Nevertheless, these are very successful bathypelagic (1000 - 4000m) animals, but why? Anglerfish are sit and wait predators and with the aid of their bioluminescent lure, can draw in prey such as fish and cephalopods (squid etc) within gobbling distance. The bioluminescent light, which can be controlled producing flashes or sustained glowing is the product of many bioluminescent bacteria that colonise the lure (or esca). They don't even need to feed particularly often since they expend such little energy, evident when you touch one of these animals. Their bodies are both flabby and bony (an attractive combination) suggesting they do very little excercise. Lazy little anglerfish. Not only are they lazy but seriously greedy. An expandable stomach allows anglerfish to munch down prey twice their size. A human man could fulfil his daily allowance of calories with 850g of meat, less than the weight of a mature trout! Seriously rubbish in comparison. 

Sea devil (Melanocetus niger), about the size of a
golf ball, look at that mouth! Image: Milly Sharkey

A female angler with the tiny parasitic male attached.
Image: Dr Theodore W. Pietsch. University of Washington

One problem that could arise, being a voracious predator in the dark munching on anything that moves, is that you might accidentally eat your mate. Finding a mate in the dark expanse of the deep sea is likely to be a very rare event. Some anglers have evolved a bizarre strategy whereby the male does not develop fully, is unable to feed properly and has enhanced olfactory senses (smell). This spurs the male on to quickly find a female before he starves, detecting the pheromones she expels into the water. When they do meet, the male bites the female, releasing enzymes that break down the skin between them, causing the two to fuse. The lucky male is now parasitic and no longer requires digestive organs, brain or his own heart (I told you they were lazy), obtaining everything he needs from the female. In return, he provides her with sperm from his last remaining organ, his gonads, a perfect relationship some may say. Bit clingy, plus he's a bit screwed...sorry I'll stop now.

More later, I need to locate pre-trawl pudding.

Milly: Ugly Fish pt 7

Milly: Ugly Fish pt 1
Milly: Ugly Fish pt 2
Milly: Ugly Fish pt 3
Milly: Ugly Fish pt 4
Milly: Ugly Fish pt 5
Milly: Ugly Fish pt 6

Always dark on the night shift... Image: web

Prepare to commence trawl two. When you have been on a night shift from 4pm to 4am and a trawl is due to hit the deck at 2am, chances are your body clock is going to be a tad confused. Last time I nearly fell asleep in my fish dissection, started writing backwards and couldn’t retain a two digit number in my head for more than 1millisecond. Not doing that again. New tactic! Since I had allocated rest time before the trawl... I decided to stay awake for 28 hours before the trawl, have a sleep then be all fresh and ready for action once the slimy catch was brought aboard. Problem with that is staying awake for 28 hours with absolutely nothing to do tends to send you a bit West. I became inaudible, talking at extremely low baritone frequencies if you can even call it talking, more like incoherent blatherings. The day shift tolerated me well. The rewards were great however, and this time, we were super fish team extraordinaire (well, we functioned without any breakdowns anyhow).




Much like last time, the trawl net was opened (noticeably more rotund this time, a good sign) and catch was spilled into a large bucket ready for inspection. Unfortunately on the last trawl we managed to scoop up a large amount of clinker (burnt coal from steam ships of the past) which made sorting through the cucumbers and delicately removing gelatinous fish nigh impossible. This time, we had little ocean floor debris so I zealously sunk my arms into the cold, slippery assortment of fish, cucumbers and crustaceans and pulled out a big, heavy object. “Oh wow, an exciting find" I thought to myself. “Doesn’t feel like a cucumber, maybe it is a big leathery fish, woohoo!" It was a shoe, a big, woman’s boot. I then proceeded to dig out two bottles and a rock. Thankfully Alan and Juliette were being slightly more sensible and actually searching for fish shaped objects and so commenced a slithery extraction of rattails, smooth-heads, some unfortunate midwater fish and a huge cusk-eel.

Is it a fish?! Is it a holothuriuan?! No. It's a bloody shoe.

Histiobranchus sp., a deep sea eel. Image: Zan 

Cusk-eel! Image: Zan 

 Lovely cusk-eel (Ophidiid). Image: Nina

We had fewer fish this time round, but they were all in really great condition, great for samples we thought, but then memories of hours in the dark surfaced in my brain and I realised that watching 3 horror films to try and stay awake was, perhaps, a terrible idea. Juliette and I managed to put aside a few minutes whilst our fish eyes were on ice to explore the trawl and the sorting process in the wet lab. It looked how I would imagine a backstreet fishmongers from a sci-fi film to look. All manner of strange beasts being weighed and measured and samples for DNA analysis being taken left right and centre. The fish were amazing. There was one fish, aptly named ‘Jellyface’ by Zan, which had a large rounded nose, a small mouth and two, what looked like sensory pits, next to the eyes. The skin on the head felt very bizarre, much like a stubbly beard. The cusk-eel felt even stranger, as you ran your fingers across its skin you felt a crackling sensation which could be due to tiny bubbles under the skin forming as the fish is brought up from depth, decompressing the air within its cells. 

'Jellyface'. Image: Zan

Juliette having a good rummage around in the cucumbers. Image: Nina

Not the most attractive of creatures.
According to one scientist this cucumber is "cute", "look at it's little hat!" she said. I later discovered this 'little hat' is in fact a parasitic anemone. The deep sea is a very strange place! Image: Nina

I had been challenged by one of my supervisors to kiss a benthic fish. Now, he may well have been joking, but I considered this something I should take very seriously and so I sought out the loveliest of all the fish in the catch, the cusk-eel and planted my lips firmly upon its slimy....mouthparts. Picture taken. Job done.

I think the picture says it all. Image: Nina

So why is all of this necessary? Larking about aside, we are taking samples for serious and important science and all possible information is always gathered from these trawls, to make the most of each catch. Stay tuned for an explanation of the science behind the sampling, most likely in the form of an interview with Juliette McGregor (she doesn't know this yet). Roll on the final trawl. Fingers crossed my supervisor doesn’t up the stakes, kissing a benthic fish is one thing, but kissing a sea cucumber, well that's a whole different level of gross.

Milly: Ugly Fish Pt 6

Deep sea Marmite from 7000m

Milly: Ugly Fish pt 1

Milly: Ugly Fish pt 2

Milly: Ugly Fish pt 3

Milly: Ugly Fish pt 4

Milly: Ugly Fish pt 5

Milly: Ugly Fish pt 7

Life on board a research ship can, at times, be rather boring. It is imperative that, to stave off derangement, you make your own fun preferably without damaging yourself or others. We have had a few ideas, after a particularly uneventful evening of mud measuring: 1) Deep sea fish top trumps 2) a horror film featuring a radioactive or chemical spill creating GIANT holuthorians, I'd quite like to call it 'Horrorthurian', not a catchy title and 3) sending weird objects to the ocean floor to see what happens to them.

During my last research cruise Alan very kindly allowed me to place a jar of marmite atop his lander and send it down into the Peru-Chile trench (7000-8000m). Sealed with a plastic top, the marmite was put under an enormous amount of pressure and subsequently its consistency was altered rather dramatically. The top layer became runny like water and at the bottom, set like concrete. I had a great deal of fun digging around in my marmite jar for hours trying to stir it all up whilst an American scientist looked on, grimacing every once in a while when he caught a whiff of its beefy goodness.

So, what does happen to things when they go down the the bottom of the ocean? Well, have a look at this polystyrene cup I put down to 4800m strapped to the lander below. Unfortunately for me, Alan, at 5am, thought it would be really funny if he put it into the bag he had been storing his bait in, before sending it down into the abyss. The reason my cup is now the size of a thimble (and strangely distorted) is due to the effect pressure has on air. Inside the polystyrene lies little air pockets that get compressed with depth, as the pressure increases. The cup is, of course, now also impregnated with mackerel juice, thank you Alan.

My polystyrene cup (left) looking rather distorted and how it looked
 before compression (right)

A previous effort...much better!

Getting slightly more creative....OCUPTOPUS!

Rather boring 'science' bit:

Pressure is measured in pascals (Pa) which corresponds to one newton per square meter (imagine one newton force as the force of the Earth's gravity on an apple). 100kPa (100,000 Pa) is typical air pressure at the surface of the Earth. With every 10m that the cup descends, another 100kPa of pressure is added, constantly squeezing the air into a smaller area until it reaches a point where most of the air is squeezed out of the cup entirely. I've been asked by an alarming number of people whether I will be doing any deep sea diving on this trip. Unfortunately, much like the cup, the air in my lungs would be squeezed out and although this can be rectified by using pressurised air (as with SCUBA diving) to fill up my lungs again, after about 60m the oxygen in the air at high partial pressure would start to poison me, forming reactive species, damaging my cells. Commercial divers are able to reach depths of 100m using gas mixtures with snazzy names like 'hydreliox' (helium, hydrogen and oxygen) or 'neox' (neon and oxygen) which have reduced levels of oxygen and are therefore less likely to cause damage. I say less because there is still the risk of inert gas bubbles forming in the blood or tissues of a diver as they ascend from depth, 'the bends'. It has also been pointed out to me that in carrying enough air for such a trip, I would be squashed like a ripe pear.

At 100m there is 1100kPa of pressure. The deepest living fish ever recorded were at 7.7km (Alan Jamieson, again) where pressure is about 77,500kPa! So how do they survive at these depths under extreme pressure?




I shall explain all in a future post...there is a trawl afoot.