We speak with Brit Finucci about the underrated yet charismatic chimaera
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Brit Finucci
Fisheries Scientist at NIWA
Deep-water sharks and chimaera
So I'm here with Brit Finuccu from Over at NIWA. Should we talk about chimaera?
Yes! Let's talk about chimaera because chimaera are the greatest.
So, can we jump off with: what are the chimaera? How do we sit them alongside everything else as Nature's Little Oddballs?
Yeah they are Nature's Little Oddballs. They are one of the oldest fish out there. They're shark and ray relatives, so they are chondrichthyans; they're a cartilaginous fish. They seem to be forgotten about… people talk about sharks and rays all the time, but it's ‘sharks rays and chimaeras’. They do differ in a few different ways, they've got just one gill slit rather than, you know with a shark you've got five, six, seven. Their skulls are fused to their jaws, which we don't see in sharks.
That's more like us isn't it? That's like how our upper jaw is part of our skull, it's the same for them.
Yeah! And the other main difference with the chimaeras which is quite unique and odd, is that they've got these appendages called tenacular’s which are only found on the males. They've got one that sits on the top of their head and they've also got a pair of them that sit right in front of their pelvic fins, and they’re used for maing purposes, which is just obscure.
Yeah I had a chat with Will [White - on our ray episode] about the alar spines on rays to figure out how that is useful for reproduction. How does a head tentacle come into play? Do we have any idea of how these things mate?
Apparently there is footage [of this]. I've never seen footage, but there are a few chimaeras that have been kept in captivity around the world and apparently there is footage out there that has shown how those appendages come into play. I haven't seen it. One day I'll try and find this out, but it does just seem obsure that this tiny little notch on the top of its head provides any sort of… I mean to be fair, when the males become mature these tenaculum become incredibly hard and calcified, and they've got all these little sharp prickles on them. I get my hands caught on them all the time. They're a pain in the butt to handle with gloves: your gloves just get ripped apart very quickly. So they're incredibly sharp. If they were to hook onto anything, they're going to hook on… they're not letting go.
Oh, okay. So it's not like a display thing?
No, it's a proper hook.
Okay! So I've only ever seen maybe [on] mature males, it's always quite flush to the brow. It's like a little bit of a crease between the eyes. But yeah, I've never seen one of the more tentacle-ey ones. So they get they get barbed and prickly?
Yeah! Pull them out from the collection and just have a play. You just have to gently scrape them, but they're incredibly sharp. The amount of times I've been trying to handle them and it just gets latched on to a glove or whatnot.
So we've touched on some of the odd elements to them, which leads us to why they're called chimaera, but I don't know if this is actually true? Is it named after the Greek monster with lots of different animal parts together?
Yes that's my understanding too, they just looked at the obscure mish-mash of this bony fish and it didn't quite fit in. So yeah, it's an obscure mix of creatures. I mean, they've got characteristics of cartilaginous fishes, but they're also called ‘rabbit fish’ because they've got these tooth plates which look like rodent teeth. Yeah, they've got that long tail, it's like a filament… this long tail. Yeah they just look like ‘yeah I'll take a little bit of this species, I'll take a little bit of that species, and we just conform it together’.
Image courtesy of NOAA
But back in the day, they were one of the dominant types of fish. And they were shallow back then and then they've been forced down into the deep sea, like a lot of oddballs have, by newer sexier forms.
I'm not too familiar with the fossil ones, but I do know there are a lot of other families in orders of chimaeras that are extinct now. There's a lot of research that goes on in the extinct world of chimeras. Yeah there's a lot more species that used to be around back in the day. But now you've basically got this very small group of up to about 55 species now. Apart from the plough-nosed chimaeras, the callorhinchids, all the other species are found in the deep ocean.
Yeah I was impressed that the plough-nosed come so close. You can see them whilst scuba diving here, which is quite exciting. So we've got we've got those, and then the two other groups are: I'm going to say ‘normal Chimaera’, and then the rhino-chimaera which are sporting quite a spoiler on the front.
Yes. So, chimaeras are grouped in the three shapes of noses, essentially. So you've got your shallow plough-nose chimaeras, which is your callorhinchids. You’ve got your (apparently normal) chimaeras, which are your shortnose chimaeras. And then you've got your longnose chimaeras, which are the best chimaeras because they've got these amazing long snouts. And they look absurd when they're young too, these snouts can account for about 50% of their body length.
It’s just like a bit in the middle, with an eye on it, and then they go to two points.
Exactly! Yes, it's just snout, eye and then this other little bit of body.
“...these snouts can account for about 50% of their body length. ”
And you can see sometimes when you get a really good image, that this snout in all of them has little tracks - little sort of stitch-marks all over the head, it's quite beautiful really. And that's their sensory system isn't it? It's particularly localized on that snout.
Yeah they've got these amazing pore systems and lateral lines that just are weaved all throughout the snout. And with the rhino-chimaeras in particular, the snouts are quite fleshy too. I’m not saying you should, but if you ever get a hold of a chimaera and give it a bit of a squeeze, they're full of kind of a gel substance that's presumably used for that sensory purpose.
So we got some some old footage of them sort of seeeping that snout over the seabed. Clearly looking for things buried in the sediment and then sort of plunging into it. And that was hypothesized for a long time. With all the new eyes in the sea, we've only recently been getting good footage of them doing this type of feeding behaviour.
Image courtesy of MARUM - Universität Bremen
Yeah but it's interesting too, because you get differences between the males and the females. At least in a few of Harriotta (Narrownose chimaeras), it was Jack Garrick who suggested that with the chimaera in New Zealand… he had a couple different measurements which kind of seemed to show that males and females have different snout sizes. So during my PhD, I did measure all the snout sizes for all the animals I had, and it does show that you get this clear difference in snout size with males and females. The male snouts seem to start increasing in snout size as they hit maturity. So whether there is some sexual characteristic to the snout is unknown.
Yeah, is it ornamentation or are they living different lives to the females?
Yeah who knows? I like to think that the males get these long noses, like with antlers and deer, they're just for showcasing how great they are with their longer snouts. But yeah, who knows?
It all looks different in the dark!
Yeah makes sense in the deep sea, where there's no light.
Trust me, I've got a huge snout.
So we've talked about the interesting upper jaw, but they've also got these fused teeth, these almost parrotfish style, sort of toothy plates. Some are for crushing, some are for cracking shells and then some seem almost like pincers.
Yeah they're more like pincers that you see in the rhino-chimaeras.
Loads of different dietary separations?
Yeah most likely. You really see like the pincer-like ones in the rhino-chimaeras, and we don't know a whole lot about their diets. I did try looking into the gut contents…
Yeah well we'll get on to that because even the gut's weird.
The gut is weird yeah. Basically the stomachs were mostly empty. But the stomachs that did have food items were mostly fish. Fish and squid. Whereas other species of chimaeras that have those crushing tooth plates, they basically seem to eat anything that's crunchy and benthic. It's a giant pain in the butt to try and tease out what the hell they've been eating, because they just mash everything into a million pieces. I have a master’s student at the moment, who's characterizing the diet of an elephant fish and I think I've made her cry many times now beacuse she's just trying to add in all these little bits. Yeah everything just gets mashed to bits.
And when we're talking about gut contents… like they don't really have stomachs, do they? They go directly to a sort of one large intestine?
Yeah it's all just one tube, that's the easiest way to put it.
Yeah which again… another another weird little throwback from them. A few people have been watching them on the divestreams and we're getting such nice visuals now… they look soft and smooth. It's not really the usual sharky-skin, they do feel glassy almost.
They're very smooth. So they don't have the dermal denticles like sharks do. And, you know, for most species, their skin is actually incredibly sensitive, they call it deciduous where it just… unfortunately when you bring them up to the surface, especially in a trawl net, it just gets damaged very easily. These species, they might be black or brown at the bottom the ocean. By the time you bring them up, they're nearly white because they've just lost all their skin. It's such a shame because they look absolutely stunning on the footage and you bring them up and it's just like ‘oh it's just this mangled little creature’ that used to have this beautiful shine to it.
It's really hard to capture in an image, they've got this beautiful blue reflective base and then this sort of deciduous skin that rubs off, on the top of the pigment. I'm thinking of the hydrolagus, that lovely velvety sort of look to it. It feels like you see through into the colour. It's really rich and it's such a shame when you see them trawlled up and it's all just scuffed off.
Image courtesy of NOAA
Yeah it's stunning. Like I said, the pictures just don't capture how beautiful these animals are. When you actually see them in person, the colours that come out.
The deeper ones tend to be a big solid colour, you’ve got crimson, there's some blues and purples in there as well. Some of the shallower ones, they're quite pretty. I'm more familiar with the Atlantic ones, the Chimaera monstrosa which is a beautiful spotty stripy shiny one with these big amber spots on this like reflective background. Are there any trends to what colour markings you find? I'm guessing the shallower ones. Maybe on a coral-ey habitat, lots of different texture?
I mean yeah, they come in all different colours. And like you mentioned, a lot of them have different spot patterns. Even within species, they are finding different colours. So that's now an issue too, where you can't just use colour to determine species. Because there were some species a few years back described from the southwest Atlantic Ocean, and one species in particular had different color morphs. So I don't have an answer to that, we just we don't have the information.
Does their smooth skin make them any more vulnerable… we know they’re more vulnerable to damage with this decidious skin, but are they more vulnerable to parasites?
Good question. I don't think the skin is in particular. But we do see some of the bigger hydrolagus species they get eye parasites.
Every single one. Every single eye.
We don't generally see the big black ones here, I know they're a lot more common in the Atlantic. But yeah, they get that copepod parasite in the eye like Greenland sharks.
Yeah it tends to be better behaved than on the greenlands. On the greenlands, I've seen it like right in the middle of the eye, whereas these are always in the corner. It looks like a tear. But yeah, they quite often have one in each eye, and then some other places are unfortunately on the claspers, and then sometimes on the base of the dorsal spine, but yeah always on the eyes. If it's an older individual, they seem to find them.
Any idea if they've gone blind?
Chimaera with parasites
I don't know. They don't seem to have gone milky like the old greenlands do. And I think this particular copepod is using it as an anchor-point, whereas the ones on the greenlands, they do actually eat the cornea, I think. Which is delightful.
Yeah it's wonderful. But yeah, the chimaeras do have their own unique cestode parasites (tapeworms) that are usually found in the guts. I can't tell you a whole lot about that, I do have a parasite friend who is absolutely obsessed with them.
We might have the same parasite friend.
Yeah so I've seen those cestode ones that get very long, and she compares it to spaghetti.
Maybe it's easier to get in when you don't have a stomach? When there isn't an acid digestion stage?
Yeah possibly.
I think again with them being one of nature's prototypes, in the deep sea there's so much less of a chance of getting exposed to parasites, that you kind of get away with things that maybe wouldn't work in shallower waters?
Yeah you have the freedom to be lazy down there.
Yeah pretty much. Because the chance of a parasite bumping into you and ever making a living hopping from you to something else…
Then you get the rattails with the dreadlocks as well, those huge copepods that they get…
Have you ever cut ratails open to find where that goes? I hate rattails. I'm telling you, they're just horrible creatures.
Just misunderstood!
No! They’re full of parasites. Dirty little fish. They can stay over in their own little corner of the ocean.
So we usually offer a little bit at the end to either set a record straight, if there's a bit that's floating around in the media that is wrong about chimaera. Or if there's something that you think people need to know beacuse they're always horribly overlooked?
Alright. So the wrong thing is going back to the tenacular, the little appendage on the top of the head. You see it often referred to… I mean they don't come up in the media often, but when they do, they're always talking about these penises on their heads. That's not true, they're not penises on their heads, they are appendages that are used for mating purposes.
And what’s something that people need to know?
So, we have no idea how old chimaeras get. We have no idea how to age them. We know nothing about that aspect of growth in chimaeras. People have tried to age them using their spines, but those have shown to be useless, essentially. There's been some exploratory work looking at their eye lenses, which falls along the lines of what was done for Greenland sharks. But this was done a long time ago, so was a lot more course and didn't involve the actual the whole stable isotope work.
“We have no idea how old chimaeras get. We have no idea how to age them. We know nothing about that aspect of growth in chimaeras.”
It’s because we can't rely on seasonality in the deep sea. As soon as you going into the deep sea, it might be seasonal pulses, but it might just have been boom and busts.
Exactly! I mean, deep sea species are generally very hard to age and chimaeras are on this whole other different level. To age things you require this hard structure that chimaeras just don't have. They've tried tooth plates as well, because they've got these little tritor ridges on their tooth plates, but correlating that with age and accounting for wear over time because these tooth plates… like I said, they eat all the little crunchy bits so wear down. So accounting for that, we just we don't know. We have no idea if they live for 10 years or if they live for 100 years. I would love to try and figure out just how old chimaeras actually get.
Some images came up recently of very hungry seals resorting to…
Yeah there are cases of that where… there was one paper that did describe seal mortality off of California from chimaera spines. And we see it here too with leopard seals. We published a paper a couple years ago, and every so often you see a leopard seal and it'll have this big spine poking out of it. Yeah they're dangerous. Do not underestimate chimaeras. You might eat them, but they'll have the final say.
Try to grabby, you get the stabby.
Yeah!
Yeah there's some gruesome pictures of seals and you can almost visualize it…. they grab the tail and that body just swings around and like a hammer.
Yeah and every so often, people get impaled by them as well. Yeah fishers underestimate them. And elephant fish are incredibly strong and yeah if you grab them by the tail, or if you just don't handle them correctly, they get you. People have been impaled the chest, they've been impaled in the hands. I mean, I've picked up boxes of chimaeras and the spines have just shot right through. So, yeah I've been stabbed by the spines as well. They're not pleasant.
They are serrated. They are they go in easy, they come out hard.
They will not be coming out! They're sharp! So yes, do not underestimate the strength of a chimaera.
Thanks for popping in and having a chat!
Thanks for having me.