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Something Fishy

FISH SMELL!

NO, fish actually smell, like, they can smell. Like, they have noses! Well, kind of. They have sensory receptors that lead to an olfactory bulb just like us.

Someone told me a joke once that went;
Did you know that a Blue Whale ejaculates 400 Gallons of sperm?
No wonder  the ocean is salty!

Now, Being someone who is familiar with the smell of male love juice (not like, whoa there slow down, familiar but a seminal musk has once or twice tiptoed over my olfactory epithelium) on hearing this joke, my peculiar brain quickly asked, Jesus! What would that smell like?

In actual fact, a blue whale typically ejaculates around 30-40 pints in each load, so as for an explanation of ocean salinity, this will not suffice. But, it did get me thinking about the smells of the ocean. And, although we might not be paddling through whale jizz when we go for a swim, we are swimming through many other smelly things. Just things that WE can’t smell.Sketches(1)

Moving past whale jizz and back to fish smelling. Smells are just chemicals drifting in the air that are sucked up by our noses and fitted into one of our 400 different odour receptors. The chemicals fit into specific receptors like a key into a lock, and that is how we decipher specific smells. Although the lock and key analogy is a little over simplified as several chemicals can fit into the same lock. It depends on what the key does once it’s inside; whether you have to jiggle it round a little, or turn it half a turn or a whole 360. This is why we can smell well over 400 hundred smells. And scientists would go as far as to say that we can discern at least 1 trillion different smells.
But to us they’re all just smells, yes some better than others, but all just smells. Fish on the other hand have 3 different odour processing areas. One for social cues like seeing how your bros are, one for food cues and one for checking out the ladies, or blokes. These chemical signals drift in the water just the same way as they do in the air. So maybe, if we could find a way of sniffing the ocean without choking we could see what these fish were smelling too. But we can’t. so please don’t try, because it’s all just going to taste like whale jizz.

Chemical signals (smells) in the ocean are kind of just being discovered and what scientists are finding out is that they’re everywhere and far more important than initially thought.  And here are two awesome ways fish use their noses.

Sketches(2)
One way is how baby fish find their way home. Thinking about a reef, some fishes lay their eggs and just chuck them into the open water to drift and hatch hundreds of miles away. They hatch into fish larvae which are kind of like human babies. Squishy, tiny (microscopic), totally useless, and don’t look anything like their adult self. Well, scientists thought they were  useless. They thought that they hatched in open water, drifted in the ocean for months, sometimes years and just settled wherever the currents took them, and that’s why their parents pooped out so many of them, because not many babies were going to survive. But tagging the larvae who had been pooped out from one particular reef, waiting a while, and coming back to look at the adult fish later discovered that an impossible amount of larvae had found their way back home. An impossible amount, if just left up to currents. It was found that these little useless critters weren’t useless at all and could actually swim considerable distances and ride different currents just like a giant subway. And what was leading the way was the smell of home. The scientist found that different reefs had different smells and even when they found their city of birth, the baby fish used smell to find a perfect new house away from danger.

And the second awesome example of smells in the ocean is coral that gather a bad ass army  of fish to do their dirty work for them. On a reef, there is a constant fight for space and a sign of a healthy reef is no seaweed. Seaweed grows at lightning speed compared to coral and some kinds of coral know this (The Acropora family). When it notices that seaweed is near, it lets out a chemical signal to tell seaweed-eating fish from all around to come and F**k that seaweed up so the coral doesn’t have to compete for space anymore.

Sketches

So there you have it, fish smell. And they smell pretty bloody well if you ask me.

References:

Atema, J., Kingsford, M., & Gerlach, G. (2002). Larval reef fish could use odour for detection, retention and orientation to reefs. Marine Ecology Progress Series, 241, 151-160. http://dx.doi.org/10.3354/meps241151

Dixson, D., & Hay, M. (2012). Corals Chemically Cue Mutualistic Fishes to Remove Competing Seaweeds. Science, 338(6108), 804-807. http://dx.doi.org/10.1126/science.1225748

Dixson, D., Jones, G., Munday, P., Planes, S., Pratchett, M., & Srinivasan, M. et al. (2008). Coral reef fish smell leaves to find island homes. Proceedings Of The Royal Society B: Biological Sciences, 275(1653), 2831-2839. http://dx.doi.org/10.1098/rspb.2008.0876

Gerlach, G., Atema, J., Kingsford, M., Black, K., & Miller-Sims, V. (2007). Smelling home can prevent dispersal of reef fish larvae. Proceedings Of The National Academy Of Sciences, 104(3), 858-863. http://dx.doi.org/10.1073/pnas.0606777104

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