Taxonomic Troubles: When is a sunfish not a sunfish?

When is a sunfish a sunfish or not? The riddle of speciation and how we define which animals belong to which taxonomic group is a long and tangled tale (and is by no means solved in modern biology!)

Sunfish having an existential crises: what am I?

To consider ‘what is an ocean sunfish’, really we need to be thinking about what makes a species? How do we define types of creature? Typically at school we are taught that a species is a group of living organisms which are capable of breeding or exchanging genes and producing viable, fertile offspring. However, as is often the case in life, things are rarely as simple as they first seem… so bring on the fun!

Speciation occurs when new environmental opportunities pop up and creatures start to take advantage! Of course some individuals may have traits that make them better suited to the new way of living than others and if they can become more successful at feeding or finding breeding sites etc. then they can produce more successful offspring with those traits and the group slowly evolves to perfectly make the most of the niche presented. This can occur through several pathways:

1) Physical division of a population i.e. by formation of a mountain range or river (known as allopatric speciation)

2) When small groups break away from a larger population and become isolated (peripatric speciation) enabling traits within the smaller group to become more distinguished

3) If a population becomes increasingly spread out over a large area they may form regional groups (parapatric speciation) where although mixing between groups is possible, it becomes less likely and each group adapts to local conditions

4) Or when new niches occur and some groups find new advantages such as different food sources to take advantage of, and despite the lack of physical barriers or distance, begin to diverge from the original species (sympatric speciation)

To make matters more complex, hybridisation between certain closely related groups is sometimes possible. An interesting example of this is occurring currently in Alaska and parts of Canada where polar bears and grizzly bears (two differing species) are suddenly coming into close contact due to shrinking sea ice forcing polar bears south, and rising land temperatures driving grizzly bears north. The two groups have been divided by habitat preferences over evolutionary time periods and each is a defined species in its own right.

However, reports of hybrids (known as pizzly or grolar bears) are becoming increasingly frequent and recent research shows that these hybrids are actually fertile. Evolutionarily speaking, it makes sense for differing species to avoid interbreeding as this would reduce specialisation to local environments i.e. a growler bear is less adapted to icy environments than a polar bear and also less adapted to temperate forests than a grizzly bear so its chances of

survival are reduced. But technically are they different species? Well if we use the traditional definition then no, but ecologically speaking yes. Confused yet? (I sure am!)

Other issues with defining a species based on the traditional “breeding and producing fertile offspring” arise from species that don’t have sex (bacteria, some lizards/sharks/plants) and it is useless for fossil species. So in practise, biologists use a whole range of concepts to tease apart what makes a species.

So come on, how do we recognise a species? Traditionally, this involved classifying animals based on comparisons of body shape (morphology), but now this also includes behaviour, evolutionary history and genetics, and yes there are still frequent arguments among the scientific community as to what can be classed as what.

In terms of the sunfishes, there are currently four recognised, defined species

1) Mola mola (my favourite naturally!) also known as the ‘Ocean Sunfish’

2) Mola ramsayi, a closely related group also called the ‘Southern Ocean Sunfish’

3) Masturus lanceolatus, the ‘Sharp-tailed Mola’

4) Ranzania laevis, ‘Slender Mola’

I will go into a more detailed overview of each of the above species in the follow blog posts (and *spoiler alert* this is by no means an exhaustive list!) Recent research suggests there might be up to 3 new species of Mola mola alone, indistinguishable to the eye, but genetically distinct… however these species have not yet been formally reviewed or named so watch this space!

Many thanks to Wikimedia Commons for providing the photographs used in this blog and as always, if you would like to get in touch or if you spot a sunfish (esp. a stranded specimen) please use the channels below:

Comments section on this blog

Twitter: @SunfishResearch

Email: nphillips01@qub.ac.uk

Trash to treasure! Strandings on the tideline

I think it’s fair to say that finding a large dead fish washed up on a lovely walk across the beach is not everyone’s idea of a great day out… however whether fresh and slightly sad or degraded and frankly disgusting, a dead sunfish slowly rotting away has the unbelievable ability to enhance my day. As a conservation biologist, I have never killed a sunfish for research purposes; however there is a treasure trove of information that can be collected from examining a dead fish, from deep tissue samples for isotopic analysis of diet, to extracting vertebrae for age analysis, there is so much still to learn about these fascinating fish! Alongside cutting edge analyses of tissues, examining a carcass also provides an unparalleled opportunity to learn about fish morphology from old fashioned dissection and exploration.

Throughout my PhD I have been seeking to collect as many stranded sunfish as possible but these are relatively few and far between. I was provided with one large individual from Lough Foyle, Northern Ireland that was kindly collected by the Lough’s Agency in 2015 (so-called ‘Murray the mola’) and last year we spotted photos on Twitter of a small specimen that had washed up in Kimmeridge Bay in Dorset, England. Luckily ‘Kim’ was found by marine biologist Julie Hatcher who kindly held on to it until I could arrange a lift to transport the fish to my parents’ house, where it lived in their home freezer for a few days until I brought it back to Belfast boxed up as my hold luggage (bit of a weird one to explain at Customs!) Following these collections I needed to organise a formal dissection, an event which transformed into one of the highlights of my PhD to date. Although I had tried my hand at dissections at school and during my undergrad degree, I had never been particularly confident in identifying one squishy blood-stained tissue from another squishy stained tissue and I struggled to get past the ick-factor, which as a wanna-be biologist left me feeling disheartened (not to mention a bit queasy!) Luckily, with a few tips and tricks on dealing with appalling smells (vapour rub under the nose works a treat) and an ever-increasing enthusiasm to learn more, I’ve been waiting for a chance to try again.

Photos: Top left, Murray the Mola; Top right Murray wrapped up in the car to Belfast; Middle left Julie Hatcher and Kim sunfish; Central row Kim’s journal from freezer to boxing to Belfast!

In Italy last year I posted a short blog about a small dead sunfish caught accidentally as bycatch in the local fishery which I carried home on the train in a shopping bag and dissected over the bidet in my rented apartment. Thanks to its strange dinner-plate shape, the ocean sunfish’s internal organs are beautifully laid out and navigation of differing organs is made simple by vivid colours which I had never noticed in undergrad classes when working on greyish farmed trout. Beneath the thick skin and muscle layers, the sunfish gall bladder is bright green, the liver a faded mustardy yellow and the heart of course a deep dark red.

After this brief exploration of sunfish anatomy, I was really looking forward to learning more about the intricacies of dissections with our larger specimen in Belfast. This experience was further augmented by the opportunity to work alongside Prof John Davenport (something of a legend in the anatomy world).  The last full dissection of an ocean sunfish was published in the 1920’s so it was fascinating to pull together all the notes we could find on their internal structure (which turned out to provide a rather limited reference library) and get stuck in!

We spent 4 days slowly working over Murray Mola from nose tip to tail exploring every tiny detail that struck us as interesting (for more info watch this space)! The whole dissection process was fascinating and incredibly valuable, from learning about internal structuring to collecting further samples for my PhD research and we all were struck with how much could be gained from a single specimen.

Photos: Above left, Whistling on the train *no sunfish dripping here…; Above right, sunfish dissection in 33 degree heat in the apartment bathroom.

It is always a sad sight when a stranding occurs, but thanks to the wonderful people who patrol the beaches and report their sightings, we can make the most of every opportunity to learn more about these incredible fish. If you spot a stranded sunfish we would love to hear about it! Please contact me using the comments section below or email me at: nphillips01@qub.ac.uk or tweet @sunfishresearch

Holy Mola; that’s a whole lot of eggs for Easter!

The Easter holidays are nearly upon us again, shops stacked floor to ceiling with an incredible array of colourful chocolate eggs… which got me thinking, why so many eggs?

The ocean sunfish (which all my thoughts eventually turn to) is well known for being the most fecund vertebrate on earth with a single female estimated to contain 300 million eggs!

But why so many? Eggs are energetically expensive to produce and tiny offspring are vulnerable to predators, so from the outskirts this seems like a strange and risky reproductive strategy.

The number and size of offspring an animal produces is often classed into two categories:

1) K Stratagists     2) r Stratagists

The animals grouped as K stratagists chose quality over quantity. They have very few young, but these tend to be larger in size, more developed at birth and enjoy a higher degree of parental care so that although fewer offspring are born, they are more likely to survive to adulthood.

At the other end of the scale are the ‘r stratagists’; animals in this category play the numbers game! They can produce millions of tiny offspring, often with no parental care at all so although the chances of survival are low for the individual, the sheer number of young produced means that one or two surive against all odds.

Of course we cannot really divide the entire animal kingdom into two arbitary classes, but this provides a useful scale to consider different stratagies for species. The ocean sunfish of course, subscribes to the r strategy with millions of eggs released into the water. We often think of this fish as an oceanic giant with few predators, but of course sunfish start as eggs drifting in the plankton only 1mm in size which puts them right at the bottom of the food chain! The eggs will float around, and if they remain in the right conditions, hatch into tiny fish fry. These fry will need to avoid predators and find enough food to survive, their best defense is to grow larger with increased muscle mass to outswim predators and become too big for predators to pick on. Of course this will only be achievable for tiny proportion of each cohort, but strange as it may seem, this is a successful stratagy that has maintained the population of ocean sunfish for millions of years.

So on Easter weekend, when you are stuffed to bursting with eggs of all shapes and sizes (as I intend to be!), spare a thought for the poor sunfish, for them this is simply business as usual.

So long and thanks for all the fish!

It’s that time of year again, spring is in the air (mostly!) and thoughts turn to summer holidays relaxing on the beach, swimming in the sea, snorkelling over colourful corals and silvery fishes. But what is the future for these seemingly idyllic ecosystems? Current research suggests that coral reef ecosystems globally are under mounting pressure, from warming seas, acidification, over fishing, tourist damage etc., however until this week I was unaware of the potentially wide ranging impacts of the tropical fish trade. As someone who has kept fish as pets and occasionally visits aquariums, I wanted to know more about how fish are sourced for aquaria displays.

A recent article from National Geographic states that up to 98% of marine ornamental fish cannot be bred in captivity on a commercial scale; therefore they must be collected from the wild, namely from Southeast Asia. According to a report from NOAA in 2008, up to 90% of the 11 million marine aquarium fish imported to the USA are caught illegally using cyanide. Although fishing using cyanide has been banned across the Philippines, Sri Lanka and Indonesia, there is little enforcement and with huge sums at stake, more and more fishermen are turning from fishing for food to supplying the aquarium trade (worth up to $200 million p.a. according to the WWF).

When cyanide tablets are ground down, they can be mixed with water and using squeezy bottles, used to flush out stunned fish from hiding places in the reef. Cyanide impairs movement and breathing in fish and with such an imprecise method of delivery, many simply die. It has been estimated that for each fish collected, a square yard of coral is killed or bleached (which of course has further knock on impacts across the reef ecosystem). It appears that both the fishermen and middle men involved in this trade are very quick to pass on their catch, as there is a high risk of fish death, even some time after collection and then of course the risk is passed onto the unsuspecting aquarium owners who will need to replace their collection if a fish dies. But what can be done to break this cycle and ensure that fish are ethically supplied from sustainable sources?

New laws are currently being drafted globally, with new legislation being debated and huge petitions aiming to make cyanide testing and certification of imported fish mandatory. However, this does not reduce pressures on tropical fishes still being collected from the wild in huge numbers, and many are now calling for only captive bred fish to be sold and traded. It is perhaps ironic that after the release of Disney’s film Finding Nemo (in which a wild fish is taken off the reef for a private aquarium and the tank fish fight for freedom in the open ocean), demand for clownfish and tangs shot up by 40% almost overnight.

Although many clownfish species can be bred in captivity, royal tangs are now being over collected and are endangered in the wild. A new app called Tank Watch (developed by the Humane Society of the United States) aims to help people trace reef-friendly species and public awareness campaigns are aiming to educate people (like me) by highlighting the potential back story of each aquarium fish.

Of course on the flip side, the aquarium trade has benefitted some rare species, such as the red-tailed black shark which is critically endangered and possibly extinct in the wild, but thanks to the the interest generated by aquarists,  dedicated breeding programs have been set up and a steady captive population now can help preserve this species.

It’s a contentious issue, with opinions running strongly on both sides, including the “Hands off my hobby” campaign of the Ornamental Aquatic Association who aim to protect the “pleasure [gained from fish keeping] as well as [the] social, economic and
health benefits” of the fish trade to the UK. On the opposing side, marine campaign groups such as Sea Shepherd have launched their “Operation Reef Defence” to end the wild caught marine fish trade.

Public support is now building for a European wide investigation into the exotic pet trade, and perhaps the end goal should be to ensure ethical standards and protection of reef ecosystems are upheld so that at the end of the day, everyone can sit back and enjoy the fish.

If you fancy more fishy facts (or if you have found a sunfish washed up) please contact me using the comments section below or follow me on Twitter or Instagram @SunfishResearch  🙂

Myth buster’s blog part 2: Farewell fake news!

Hello and welcome to Part 2 of the special edition Myth Buster’s Blog!! Following the fishy facts touted by sunfish-loathing Scout Burns that went viral last week, I have been exploring the incredible ecology of the ocean sunfish and answering a lot of fake news claims! So buckle up and get ready for a whistle-stop tour of fascinating (and scientifically verified!) fish facts.

My favourite issue that Scout has with sunfish is that despite being “so huge” they are not even “decent predators” …unless you are a prey item of course! The key biological definition of a predator is ‘an animal that naturally preys on others’ and so sunfish are actually classed as oceanic predators!

With jaws not-so-dangerous to people, the sunfish (or Mola) is a voracious predator of gelatinous prey!

 If we consider a “decent predator” as one which is harmful to humans, then as Scout mentioned, sunfish can be dangerous due to their incredible size and are alleged to have caused a death already by breaching and hitting a person. But as a biologist, this doesn’t seem like the best method for classifying predators…(although it should qualify as entry to the Darwin Awards!)

Back to sunfish prey items, (an area quite a few researchers have been working on over the last 5-10 years,) Scout states “They mostly only eat jellyfish because [it has] a possibility of drifting into their mouths I guess. Everything they do eat has almost zero nutritional value and because it’s so stupidly fucking big, it has to eat a ton of the almost no nutritional value stuff to stay alive. Dumb.” Again, this statement needs a bit of work to reach the underlying truth… Yes sunfish mostly eat jellies, but for smaller sunfish (<1 m), up to 40% of their diet is actually made up of seafloor creatures including crustaceans, molluscs and even some fish species. I even wrote a blog post about this 3 years back…

So many choices….

To find jelly prey in the open ocean, not just jellyfish medusae but also other gelatinous creatures such as siphonophores, ctenophores and pyrosomes (see photos!), is a tough job. Sunfish constantly patrol the world’s oceans searching for prey, travelling long distances both horizontally and vertically to find their food. When they locate prey items, such as a jellyfish, they know to only eat the most energetically nutritious parts, the gonads and oral arms (yum!) before leaving the rest as not worth bothering digesting. It’s an incredible strategy that not many creatures are physically able to exploit and something that we are still trying to understand and explain.

Sunfish prey items clockwise from top left: Ctenophore – (Bolinopsis infundibulum), Siphonophore (Marrus orthocanna) and Pyrosome (unknown species)

Photo credit www.photolib.noaa.gov, en.wikipedia.org/wiki, carnivoraforum.com

Scout then moves on from thinking of sunfish prey, to thinking of sunfish as prey: “They do sometimes get eaten though. But hardly. No animal truly uses them as a food source.” Again, this is a little misguided. Although larger sunfish are less predated on (but have still been found inside large sharks, sealions, orca etc.) the sunfish start out life in the plankton as tiny eggs less than 1 mm across. This puts them on the menu for almost every creature in the sea! As they grow, the number of predators able to cope with such a large item decreases, but they are still removed from the world’s oceans in their hundreds of thousands by… you’ve guessed it: us! There are huge markets for ocean sunfish meat across the Far East (Taiwan and Japan in particular) and they are also captured as unwanted bycatch by fisheries across the world. It is these enormous catch figures that have led to the ocean sunfish being classified as Vulnerable to extinction by the IUCN Red List.

Fisheries capture of ocean sunfish and a dish made of sunfish

(Photo credit; Lukas Kubicek and commons.wikimedia.org)

Scout reckons their survival strategy is dependent on the sunfishes extreme fecundity, “it would be statistically improbable, dare I say impossible that there wouldn’t be at least one… left surviving at the end of the day”. The sunfishes incredible fecundity has been estimated from one study that suggested a single female could contain up to 300 million eggs, (although it is highly unlikely that a sunfish would release all their eggs at once!) This number is brandished a lot in ocean sunfish ecology, but we need to remember this figure was estimated from one fish; it does not represent the average number of eggs per sunfish and has not been examined further since the original study in 1921…

The statistically probability of larvae survival is harder to predict… in cases of extreme fecundity (known as being an r-strategist) an animal must produce lots and lots of offspring because the overall odds of survival are minuscule. We don’t currently know how many sunfish there are in the seas, but it appears that not many of these offspring survive otherwise evolutionary speaking, it would be an unnecessary waste of resources and not selected for.

A simple outline of species reproductive strategies:

1. “K strategists” which have fewer offspring with higher energy input and high parental care which are more likely to survive (e.g. polar bear)
2. “r strategists” which have high abundance of offspring, with low energy input and little to no parental care which have a poor chance of survival (e.g. ocean sunfish)

Of course this rant does not, in my opinion constitute as “proof that God has abandoned us.” But unfortunately Scout feels so strongly to “hate the f*** out of this complete failure of evolution… if I ever see one, I will throw rocks at it.” As much I as love to introduce people to the incredible species I work on, considering that we currently believe these fish are Vulnerable to extinction and seem to have an important role in ecosystem functioning, (and animal cruelty is frowned upon), perhaps it’s best that these two never meet.

If however, anyone ever has any questions on ocean sunfish or wants to know more details about their fascinating ecology please head to my twitter page @SunfishResearch or visit my blog sunfishresearch@wordpress.com

 

Something Sounds Fishy! Myth Buster’s Blog (1 of 2)

Incredibly it seems the ocean sunfish has gone viral yet again! I know, I was surprised too! Firstly Boston Man broke the internet with his ideas of catching a ‘baby whale’ (*spoiler, it’s a sunfish!) and now an incredible rant about the “biggest joke played on earth”, again with sunfish as the butt (or should that be swimming head) of the joke! I love a good rant (esp. David Mitchell when he goes off on one), but in the dark days of fake news, there are a few little problems with Scout Burns’ epic tale of “wasted space” that I feel we should explore.

Fishy News Stories…. Time for #FridayFacts!!

Scout has made some pretty big claims about sunfish, the scientists who study them and even the process of evolution itself so I feel it’s time someone stood up for the funny-looking fish and for science itself, so in response today we have a special #FridayFacts edition: The Myth Buster’s Blog!

At the beginning of this viral rant, we are told that sunfish are just “big, dumb idiot[s]” of “the biggest joke played on earth” made when “God must have accidentally dropped [one] while washing dishes one day and shrugged his shoulders” because they have “no purpose… every foot… wasted space”. Of course we cannot agree with this, the ocean sunfish is the brand new kid on the block when we come to looking at species evolutionary speaking! Whereas the fishes as a group first emerged around 500 million years ago, the ocean sunfishes represent cutting edge evolutionary design, having evolved only around 50 million years ago!

Dishes?! More like cutting-edge design

The ocean sunfish showcases a fantastic body honed by selective processes over millions of years, perfectly adapted to a life travelling the world’s oceans. As to their purpose on this planet, this is a bigger question to answer… the meaning of life has been hotly debated for centuries from ancient philosophers to Monty Python (of course the real answer is 42!). But roughly speaking, their “purpose” is the same as the rest of all lifeforms on earth… simply to exist and pass on genes: to feed, grow, breathe, reproduce and die.

The meaning of life and the sunfish life cycle (adult produces offspring as eggs, through larval stages, growing from juvenile to mature adult and the whole cycle starts afresh!)

Of course, having an interest in biology, we want to know a few more details than that! Which is why scientists (myself included) are trying to unravel the complex ecology of the sunfish a little further… but when it comes to scientific understanding, Scout suggests “scientists even debate how [sunfish] move. They have little control… some say they must just push water out of their mouths for direction…They could use their back fin, except… it doesn’t f****** grow. It just continually folds in on itself.”

Now as funny as the idea is of a giant sunfish blowing water to presumably jet backwards (!?!), I am sorry to report that this simply isn’t true. We know how they move and in quite a lot of detail. They use their dorsal and anal fins like a pair of wings to soar through the oceans, undertaking long distance journeys of up to 48km a day! Their funny little caudal fin (known as the clavus) grows of course, and has a vital function (otherwise evolutionarily it would have most likely have been lost!), and is used like a ship’s rudder to steer the fish as it swims.

Similar structures; ships rudder and sunfish clavus

Scout correctly mentioned that sunfish don’t have swim bladders; however it is not true that “that every fish has [one] to make sure it doesn’t just sink to bottom of the ocean… [and sunfish] can barely move to begin with”. Lots of fish do not have swim bladders, for example sharks, as there are other evolutionary designs that can provide lift without the issues of containing air internally (such as problems with rapid descent and ascent). Most fish without swim bladders, including sunfish, have large deposits of fatty lipids in their livers that provide buoyancy = no swim bladder, no problem!

Some of the sunfish’s fellow fishes without swim bladders (left to right: manta ray, great white shark, basking shark, white marlin)

Aside from preventing sinking, Scout also mentions that sunfish seem to “get stuck on top of the water… because without the whole swim bladder thing… the ocean pushes over the [fish]”. This idea again presents a great image, but unfortunately is untrue. The sunfish does not need a swim bladder to remain upright (it’s not a life jacket); they are perfectly capable of swimming upright both at the surface and at depth. Sunfish are often noted “basking” at the surface where they lie on their sides which enables them to increase the rapidity of their heat exchange, to communicate with birds for parasite removal and perhaps simply just to rest, before diving back into the depths (up to 844m deep!)

Seeking the sun in deep, dark places! Ocean sunfish photos at depth

So that’s all we have time for in this Myth Buster’s Blog edition but I will be posting part 2 next Friday to question the remaining “fishy” facts in the “sunfish are useless animals” rant and of course to provide some illuminating answers! *Spoiler alert, sunfish are awesome super-predators!

If you just can’t wait another week for more sunfish news, please check out my twitter @SunfishResearch or please feel free to ask a question using the comments below 🙂

 

Getting crafty for Science! From paddling pools to pleather harnesses, all in a day’s work!

I am often asked where I find equipment for my research, (obviously sunfish harnesses can be tricky to buy off the peg)… and so this blog is all about sourcing strange bits of kit! Please dive in and feel free to laugh a lot at the awkward places I end up, all in the name of science!

A common strategy for many scientists is to make your own/adapt/invent things to fit your fieldwork and although this may seem a bit Blue Peter “here’s a floating, lightweight holding net I made earlier”, it saves a lot of money and time in the long run!

A “how to” make a floating net (including demo ‘fish’ capture in last photo…)

So to start the blog for 2017, here is the official Weird Kit List! The top 3 things I have bought or made in the name of field work (so far…)

   At number 3: The beef jerky maker/high tech stable isotope dryer!

The state-of-the-art isotope lab in action (in my b&b room *phew!)

At number 2: The suspicious hand pump/chlorophyll extraction device!

The hand pump in action on the beach filtering liters of seawater in double quick time!

And at No. 1: The pleather lovers’ dream/sunfish-harness-making material!

Customised sunfish belts for all!

So as you can see, it’s well worth being a bit inventive (and having a sense of humor) when working in the biological sciences!!

Here’s to another year of invention & adventure and wishing you all a wonderful 2017!

As always if you see a dead sunfish which we could take samples from or just fancy a chat about fish/PhD life/getting crafty for science please get in touch! 🙂

Email: nphillips01@qub.ac.uk

Twitter: @SunfishResearch

Instagram: @SunfishResearch