Fantastic fish and where to find them (in the UK)

Fantastic fish and where to find them (in the UK)


Some people wonder why I bother going diving
in the UK – after all it’s bloody cold and you’re not going to see much wildlife,
let alone any interesting wildlife. While it’s true that UK diving requires more than
a few of the warmest thermal layers ever invented, the animals and algae you see when you’re
down there more than make up for it. I’m going to take you on an underwater safari
of the best marine wildlife I’ve saw on a single dive trip off the south coast of
England. But as an evolutionary biologist, I’m going to present them from least related
to humans to most related to humans. This isn’t to say that humans are in any way
better than everything else (we’re not) or that we are the pinnacle of evolution (we’re
not) nor that we’re the most complex (we’re not). It does mean we can see which adaptations
happened a really long time ago and so are found in most of the tree of life, and which
adaptations happened more recently and so only affect one or two branches. So squeeze
into your drysuits and load up your lead as we fall backwards into an underwater jungle. I always thought of algae as the boring bit
of the marine habitat; the frame in which the beautiful animal picture hangs. Turns out their
biology is so complex and interesting there’s no way I can fit it all in here. Just as you
may have heard there is no such thing as a fish algae is a similarly
meaningless word, as technically land plants are a type of green algae, but there are also
red and brown algae that are completely different from plants that are also in the algae grouping.
Much of the UK coastline is kelp forest, and just like trees in a forest, the kelp provides
shelter and structure while also absorbing and fixing carbon. Globally, kelp forests
capture 75% of the carbon fixed in the sea and are one of the most productive ecosystems
on earth. It’s honestly stunning swimming through these enormous trunk like fronds,
catching glimpses of fish, then seeing a mat of reds and pinks and purple algae covering
the rocks. Leaving behind the plants and algae, we have sponges, the most basal animal group, meaning
they split off from the rest of the animals ages ago and so lack many of the adaptations
we see in other animals. They’re not lesser animals for it; they have after all survived
as a group for far longer than us mere mammals, but when you look at a sponge, it’s hard
not to call it primitive. They don’t have true tissues or organs,
there’s no head, and no anus. However, this lack of complexity in the types of cells does
give them one major superpower. You can pass a sponge through a sieve to break it up into
individual cells, and not only will the cells survive, they will regroup and form a whole sponge again. Just don’t even imagine doing that to a human. It won’t end well. And we’re on to the cnidaria, that’s your corals, anemones and jellyfish. We’ve gone
up a level in cell complexity and have two layers of cells with a jelly filling. That
does mean we only have one orifice for eating and excreting though – a mouth anus if you
will. But although they have simple tissues, they have evolved a wicked adaptation we don’t
have. Cnidaria literally means nettle animals because these have evolved stinging cells.
And not just any stinging cells. These cnidocytes are trigger activated, hydraulic propelled
harpoons that can have piercing barbs, toxins, lassos or glue. That’s hardly primitive.
If they can pierce human skin the toxins are some of the most fatal in the animal kingdom.
If they can’t, like beadlet anemones, it just feels sticky or grippy. Ah we’ve reached the arthropods. From this
point onwards, all the animals are bilateria. We’ve got three cell layers during development
which means we can now evolve a complete digestive tract with a separate mouth and anus! Hooray!
Biologists are so obsessed with mouths and anuses that we split all the animals from
this point into the ones that grow a mouth first as an embryo (the protostomes) and the
ones that grow an anus first and a mouth second (the deuterostomes).
Arthropods are a group of protostomes, and boy are they a diverse group. In the sea, we have malacostraca instead of insects; the crabs, lobsters, crayfish, shrimp
and woodlice. To once again drive home the point that just because a group split off
earlier along the evolutionary tree doesn’t make it basic or primitive or less evolved,
just listen to this parts list. They’ve got 2 pairs of antennae, compound eyes, three
pairs of mouthparts, eight pairs of legs from the thorax, some of which might be specialised
into pincers for feeding/defence, 6 pairs of appendages on the abdomen or swimmerets,
which might also be specialised into catching food, brooding eggs, delivering sperm, bearing
gills. Special shout out to the spiny lobsters we
saw in Cornwall. These were almost wiped out from over fishing because they live so long
and take so long to reproduce. But they’ve been made a priority species on the UK Biodiversity
Action Plan, and because we were diving next to a Marine Conservation Zone where human
activity is restricted, we were able to see quite a few as the population is recovering. We’ve reached the group where the anus forms
first! The earliest branching of the deuterostomes is the echinoderms or the spiny skinned; that’s
your starfish, sea urchins and sea cucumbers. Once again, they’ve evolved powers we lack;
they have hydraulically powered tube feet which they use to move around and grip onto
food, and they can regenerate legs and internal organs. You’ll often see starfish either
missing a leg (or three) but they’ll be absolutely fine and will just grow another
one. Sea cucumbers can also squirt long sticky
tubes at threatening predators, entangling and immobilising them for long enough for
the cucumber to crawl away. However, I have to read to you one description of how they
do it: “it faces away from the attacker and contracts its body wall muscles sharply.
This causes the wall of the cloaca to tear and the anus to gape and the free ends of
some of the tubes to be ejected. Water is forced into these tubules causing a rapid
expansion and they elongate by up to twenty times their original length”. Ouch. Aaaand we’re finally at the more recognisable
animals – the vertebrates. Vertebrates includes your five big groups – the fish, amphibians,
reptiles, birds and us mammals. And, as I know you’re all wondering, we are deuterostomes
which means our anus forms first! We start off as a hollow ball of cells and that first
invagination becomes the butt. We’ve now evolved jaws and an adaptive immune system.
Within the fish group, we have the chondrichthyes and osteichthyes aka the fish with cartilage
skeletons and the fish with bony skeletons. The cartilaginous fish includes the sharks,
skates and rays, and yes, sharks are fish and yes there are sharks in the UK. I saw
a couple of lesser spotted dogfish but we also have basking sharks (the second largest
fish in the world) plus about 30 other species of shark that visit British waters and none
of them will attack a human unless provoked. Recent research on this type of shark found
that sharks have personalities, aka a repeatable behaviour across time and contexts that differ
consistently among individuals. Social dogfish were happy to hang out in conspicuous groups
in a new habitat, whereas the less social sharks preferred to camouflage on the gravel
bottom, staying hidden on their own. We have now evolved bone! And there’s also an anal upgrade: we now have separate openings
for the anus, urine and genitals. And if you didn’t think there was already enough terminology
with the osteichthyes and chondrichthyes, the bony fish are also split into two, the actinopterygians
and sarcopterygians aka the ray finned fish and the lobe finned fish. I mean just take a second. I had to memorise all of these terms for my undergrad degree. Take pity. The ray finned fish, or actinopterygians, make up pretty much all of what we think of when we think of a fish,
including these wrasse. Wrasse are super common and there are over 600 species, so when in
doubt, we divers call every fish a wrasse! The word wrasse comes from gwragh meaning
old woman, which is the same root as the word hag. Which is fitting, because like haggard
old women, wrasse are colourful and beautiful. All wrasse start off life as females and them
some become males later in life. Usually there is a single dominant male and when he dies,
the most senior female will change sex and take over. This is the opposite of the clownfish
in Finding Nemo, where Nemo’s dad would almost certainly have been Nemo’s mum by
the time they reunited. And finally the sarcopterygians, the lobe finned fish. You might not think you know much about the sarcopterygians
but in fact you know them intimately. And that’s because humans are strictly speaking
lobe finned fish, as are all the other land vertebrates. Usually we exclude the land animals
from this grouping but this is only for convenience, and doesn’t make any biological sense when
we’re considering who is most related or who is evolved from whom.
Around 380 million years ago, some fish found their stubby bony fins were quite good at
crawling through shallow water that was full of mud and dead leaves. Being able to gulp
air and hold it in lungs was really handy for breathing in stagnant water. Fish were
still living in the water when they evolved legs and lungs, but once they had them, they
were able to colonise the land. Over the next few hundred million years, some
of these land fish evolved hair and homeothermy to keep warm, a big muscle called the diaphragm
to breathe, and bigger brains to find food. Then a few of these lobe finned fish decided
they actually still like being able to go under water after all. They weren’t very
well adapted to life underwater and had to invent these ridiculously heavy and complex
tanks, masks, hoses and suits. But that’s a story for my third and final scuba video
in this series – how exactly DO you go scuba diving in the UK? Hello, and welcome to my highly professional voice-over recording booth. Isn’t this great? What’s also great is this video is sponsored by New Scientist. I love getting paid! Thumbs up! So if you didn’t grow up with New Scientist like I did, they are a science and technology magazine both online and in print, and they write articles about new research, new papers that have just been published technology, the environment, all these sort of things, but it’s all for a general audience so it’s all really easy to understand And with the link in the description, you can get 10 editions of the magazine for just £10 which is in itself a great deal, but also at that link I have curated 3 articles that I think you’ll enjoy based on this video so they’re all on marine biology and evolution There’s one on fish that have a dawn chorus and they have the audio file so you can listen to the dawn chorus over a coral reef which has just been discovered There’s one that some sharks have been found to be glow in the dark And my favourite one, and bear in mind that New Scientist have no editorial control over this video They didn’t know what this video was going to be about. They already had an article about comb jelly anuses So like jellyfish, an anus that comes and goes at will. How perfect is that for this video? So if you want to say thank you to New Scientist for giving me money and helping me continue to make a living making YouTube videos If you want to get that amazing 10 for 10 deal and read more about jelly anuses Then just go to the link in the description. Thanks!

29 thoughts on “Fantastic fish and where to find them (in the UK)

  1. You've been killing it lately with such high quality and interesting videos! Waiting for the next video now!❤

  2. Nice video! I loved how you went along the evolutionary tree and explained what changed/was new from the last group! Also the sound quality was really really nice.

  3. Hey Sally, This video was awesome, and I'm loving the new style! , but constructive criticism, maybe some gentle background music to help set the atmosphere?

    Much love, looking forward to your next video 🙂

  4. Gurl your presentation has become top notch, so much work on your channel since you finished your studies. I'm impressed by the diversity and the quality of the content. Please continue like this. You are awesome and i am glad to have stuck around

  5. New audio recording setup? Sounds crisp. Oh and I really enjoy the videos of this format and subject. Would like to see more (but not expecting many, as it is probably fairly hard to plan, shoot and edit).

    On a related note, I was pleasantly surprised when I did some dives in my country's similarly conditioned cold water. I can still speak with joy about those dives: crisp blue water, spiny lobsters (or similar) in artificial lobster-homes (probably same priority species program), anemone in all colours, bright green kelp and other vegetation. If it wasn't for the 11°C water temperature (in a 7mm suit), I would have said it was a type of dive similar to the more 'traditional' diverse marine wildlife diving locations (Bonaire, Malaysia etc.). Visibility, on the other hand, is most often not so great.

  6. I absolutely love that you explain how humans are not the pinnacle of evolution while showing you awkwardly try to get on the boat! Very poignant and funny

  7. I would never have guessed there was such a range of gorgeous wildlife in cold water. I thought all the exciting stuff was in the warmer waters. Thank you for showing me otherwise.

  8. A paper that I can't access appears to suggest that Henricia was named by John Edward Gray in 1840 (which Gray does not explain in that paper) for Johann Heinrich Linck (Iohannis Henrici Linckii) who published a monograph on starfish in 1733. He included a description and picture of what would be later called Henricia oculata as Pentadactylosaster oculatus. He had the genus Linckia already named in his honour when Gray published Henricia. Edward Forbes tried to name these starfish as Linckia but the name was already taken. So the original Bloody Henry was actually a John.
    Thanks for not falling for the weird idea that starfish should not be called fish because they are not the same as "real" fish. Silverfish and shellfish are also ancient words in English. Sea star just sounds so generic.

  9. How dare you say Humans aren't the best. Can anything in nature make a cheesy gordita crunch from taco bell? I didn't think so.

  10. Yet another informative and amusing video by Sally! And good for New Scientist for sponsoring the video! I SO look forward to seeing the "new video" indicator for Sally's videos. A chance to escape the world into science!

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