Hello, everyone
we are down in our mollusc collection today with researcher Suzanne Williams,
and we've been finding out all about a particular type of mollusc,
a nudibranch called a sea bunny.
Now, if you haven't seen that video, check that out,
the link is on the screen and down in the description.
But we've got some other really special specimens we're going to look at today as well.
But let's start with those sea bunnies Suzanne
what are we talking about here? Nudibranchs?
Nudibranchs, they're marine sea slugs
and they're very pretty, very very colourful sea slugs.
They're not like garden slugs at all.
They are absolutely beautiful
and they're very varied as well
sea bunny is one nickname for one type of nudibranch, but there are more, aren't there?
Yes, we have in the UK, we have sea lemons, which are very cute.
And we have sea dragons, which live in the open ocean.
They live in the very top surface of the open ocean and they predators,
they will eat the stinging cells from the man of war jellyfish.
We also have Pikachu nudibranchs, and Shaun the Sheep nudibranchs.
I advise you to check out Shaun the Sheep nuidbranchs. Google it, very very cool.
It is, it's very nice.
So how many different species are there?
There's about 3000 different species.
That is pretty incredible.
And where do we find them? We've got some in the UK, in the open ocean. Are they pretty much everywhere?
They are, they're in every ocean they're from shallow to deep.
They live on bryozoans, soft corals, algae and sponges.
Wow. That is incredible.
And they are, as you've mentioned, very, very beautiful.
Some of the most colourful animals, I think, in the ocean, aren't they?
So why so colourful?
Well, it's a good question.
The colour is really important for many animal's survival
and with nudibranchs they're one of our best examples of warning colouration.
So many nudibranchs take up toxins from the food they eat,
from sponges and soft corals, and they sequester those toxins inside their flesh
and then they make themselves very brightly coloured to warn potential predators
that they are unpalatable and possibly toxic.
Absolutely, it's hard to see some of our examples today,
but they are very, very beautiful, very colourful.
Is it just for defence, though, or are there other other uses for this colour?
Well, colour in other species is useful for finding a mate.
That's probably not relevant for nudibranchs because they have very poor eyes.
They use their rhinophores and little tubercles on their back
for sensing chemicals in the water to find mates and food and predators.
But another thing that colour is often used for, colour and pattern, is camouflage.
And some nudibranchs do use colour for camouflage.
And we've got a particularly interesting example here, haven't we?
Can you tell us a little bit about these two specimens you've got?
Yeah, these are really nice.
This is a sea cucumber, this is not a nudibranch.
This is a nudibranch, this is Phyllidia varicosa.
This is a very brightly coloured nudibranch in life, not in our Museum collection.
Many colours fade in museum collections, so most of our collection is brown.
But in life they're very colourful.
This sea cucumber, when it's a juvenile and very small and the same size as the nudibranch
it has the same colours and pattern, so it mimics these nudibranchs.
these nudibranchs sequester poisons from the sponges that they eat
so they're toxic and unpalatable to predators
and the sea cucumber just hitchhikes on this benefit
by producing this same sort of colour and pattern.
Of course, once they get bigger, it's no longer able to pretend to be a nudibranch
and it changes colour and actually sequesters its own toxins as well.
It's incredible, taking advantage of another poisonous mollusc.
It's brilliant.
Are there any colours that are particularly rare in in sea creatures.
Yes, it's really interesting.
Not all colours are equal.
You find that some colours and particularly blue and green
are rare colours.
So we have some green shells here for you to look at.
And you would think that green is a fabulous colour for camouflage.
Many snails particularly live in plants and this would be
a great colour for hiding, but you don't find very many green shells.
And we think this is partly because green pigments may be hard
to make and hard to incorporate into shells.
Are there any green nudibranchs?
There are. It's really cool.
There are a group of nudibranchs known as sacoglossans
and they actually eat algae and they will take up chloroplasts
from the algae that is still actively photosynthesising
and they'll incorporate them
into their mantle tissues and then they use them to photosynthesise.
So they will get energy from these chloroplasts
that are photosynthesising just as a plant does.
And if they're in an area at a time when there's not very much food
or it's a bit dark and it's not working for photosynthesis,
they can then just eat the chloroplasts
so there's benefit both ways.
And also from camouflage because the animal is green.
So it's hiding in the plants.
They are amazing animals.
I had no idea that they were they were so complex and interesting.
This has been absolutely fascinating.
Thank you so much, Suzanne.
Thank you. Yeah, brilliant.
Thank you so much for watching.
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