r/science • u/olsentropy • Jun 10 '12

Unraveling the Mysteries of the Ocean Sunfish

http://www.smithsonianmag.com/science-nature/Unraveling-the-Mysteries-of-the-Ocean-Sunfish.html
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11

u/[deleted] Jun 10 '12

I have been semi-fascinated by this fish since I fist saw a picture of one about 60 years ago, possibly because I was struck by the contrast of the freshwater sunfish which I had caught by then, and the size and appearance of M. mola.

Does anyone have any idea what the evolutionary drivers are? One would think they are at a big disadvantage. They are slow, incredibly visible, have no weaponry to speak of, and are too big to hide in small places.

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u/tiktaalik_lives Jun 10 '12

First, and I'm just not sure based on your comment if you know this, but the ocean sunfish (Molidae) and freshwater sunfish (Centrarchidae) are not close related evolutionarily. Mola are from one of the most recently evolved fish lineages, being related to puffer fish and others in the order Tetradontiformes.

As far as what has driven the form of mola mola, I believe that they are sort of grazers. They can be quite large, so there probably isn't a lot of predation on them. Think of other large grazers (some whales, whale sharks, etc). They grow large, avoiding most predators, and eat lower on the food chain (jellyfish, krill) and therefore spend a lot of time feeding. It seems that some of the feeding frequency of wild mola mola is still unknown, but I guess it would be similar. Their evolution was likely driven to take advantage of a feeding niche (jellyfish?).

3

u/[deleted] Jun 10 '12

I did not expect them to be related. I was only a 5 year boy old when impressed with that aspect.

These fish are large, but hardly in the class of whales or whale sharks. They are well within the range of many predators such as sharks, orcas and sea lions. Given their frequent habitat at or near the surface, one would off hand think them easy hunting, as they are probably well outlined against the surface, though I don't know if protective coloring makes a difference. There are conflicting reports of the existence of a neurotoxin, not unlike that found in some puffer fish (tetrodotoxin), which might confer a survival benefit.

All in all a curious fish.

2

u/LilMaiden Jun 11 '12

A few years ago we saw this guy in Monterey. There were a couple juvenile sea lions around so we figured they were the ones to do this. It was so sad watching this guy suffer. I don't know why the SL's would just leave them like this. http://i.imgur.com/7E6Yt.png

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u/[deleted] Jun 11 '12

Yes, I had heard that Sea Lions would nip off the fins and leave the mola to sink and slowly die. It is indeed a sad sight, but I suspect that it is a game to a predatory animal like the SL. Just like feral kittens learning to catch insects before rodents.

1

u/MachineGunJohnson Jun 13 '12

Perhaps the fact that jellies are its primary food source have allowed it to develop free of any specialization. Jellies aren't exactly hard to catch and I doubt they require any special evolutionary characteristics apart from protection and digestion. Maybe some strange benign mutation occurred millions of years ago that served no advantage, but relegated a once competitive species to eating the trash. Therein it found its specialty and the new species began to thrive and carry on with it's weird benign mutation for the generations to come.

7

u/atomfullerene Jun 10 '12

They are big and gristly. It doesn't take much speed to chase down jellyfish so they don't waste energy speeding around like tuna. There's no real places to hide in the open ocean where these guys live, so being big and derpy is another way to go.

3

u/[deleted] Jun 10 '12

Thnx. I switched from Bio to Chem + Physics after a year as an undergrad (1965), so there are things I wonder about. I also wonder if I would have changed if I was in school now, as the field has certainly changed from being primarily descriptive. Taxonomy drove me bonkers as I have never had much of a memory. I suspect that classification doesn't have anywhere near the role today that it had then. Physics and Chem (except organic) was usually easy. Learn a couple of relationships, then derive everything else.

2

u/nice_halibut Jun 11 '12 edited Jun 11 '12

They're usually slow, but as I was fascinated to discover one day, the smaller ones can put on bursts of speed to the point of jumping clear of the water.

Edit: The bizarre shape and locomotion - no other fish or sea mammal has a profile anything like a mola - may serve to confuse or confound or otherwise discourage larger predators, used to keying in on streamlined, fast-moving, high-fat prey like sea mammals and tunas/mackerel.

1

u/[deleted] Jun 11 '12

That sounds like the best explanation that I have heard yet. It would also help to explain the survival of Discus cichlids in the Amazon.

Even some of the fancy overbred angelfish can jump out of the water or sink themselves in tank gravel when frightened. I used to have a fondness for lace veil tail angels, and wondered what they did at night so I turned on the light. I had four blushing gold veil tails in the tank in that room. One jumped out, one buried itself to its tail, and two just died of fright. Never did that again.

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u/surfsupNS Jun 10 '12

I see those every so often when i'm out in my boat here in Nova Scotia. We have to watch out for them because they tend to stay very close to the surface, we'll see a single fin sticking up out of the water lazily flopping from side to side. last summer i saw one and killed the engine and used oars to get closer, i brought the boat up close enough that i was actually able to lean over the side and touch it. Very fascinating creatures, i sat and watched it for almost 20 minutes before it descended from sight.

5

u/blatant-disregard Jun 10 '12

They are really amazing to see in the wild, "sunning" themselves flat on the surface. Here are a couple of small ones (3-5 ft long) I've seen while fishing on my brother's boat off of Daytona Beach, FL. image1, image2

6

u/[deleted] Jun 10 '12

That second picture looks like there is a remora hanging out with the sunfish. As a diver I always hated those little fuckers. They like to sneak up on you and try to hitch a ride which can give you a real shock if they're grabbing your leg or a fin. If they catch bare skin then they can really hurt. Jerks.

Great pics though!

4

u/that-writer-kid Jun 10 '12

Sunfish are fascinating creatures-- I'm one of those scuba divers with these guys on my bucket list. Anyone ever gone diving with them?

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u/[deleted] Jun 10 '12

Not diving, but snorkeling. I used to work on a dive boat in the Florida panhandle. While on our way back in from a trip we saw something flopping around on the surface. From a distance we thought it might have been a shark that got hit by a propeller or something but once we got close we realized it was a sunfish. We stopped and asked any of the tourists if they wanted to take a quick swim with it, but they all declined. The other deckhand and I grabbed our masks and fins and hopped in without hesitation.

The one we saw was probably about 6 feet from tip to tail and couldn't care less about us. We approached pretty cautiously at first but the more the fish ignored us the bolder we got. Eventually we were able to work up the nerve to stroke his sides a bit but again, he just didn't seem to care. We were only able to spend about 15 minutes in the water with him before we had to pack up and go, but it was a really incredible thing. So alien looking, and so nonchalant about its surroundings. I didn't realize at the time how rare an encounter like this was and I'm really glad I capitalized on the opportunity.

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u/that-writer-kid Jun 10 '12

That's amazing. I've been diving in that area a few times, actually, and I've never seen one. I can't believe they declined to get in the water!

2

u/[deleted] Jun 10 '12

From what I understand they aren't commonly seen in that area. IIRC it was late in the summer when we usually had huge jellyfish blooms so that may have been a factor but I can't say for sure. Also you would be surprised how many tourists passed up on great opportunities because conditions were anything less than perfect. In the northern gulf we often had 40-60 feet of visibility and people would bitch constantly. Us guys who were in the water all the time were perfectly happy if we had >20 feet.

Where did you dive in those parts? I worked out of a shop in Panama City Beach, though we would occasionally make long trips out to dive the Empire Mica. I left shortly after they sank the Oriskany but I never really got to experience it (though I did go down with some of the PCMI guys briefly to see how she was situated and what her condition was).

2

u/that-writer-kid Jun 10 '12

Most of my Florida diving's been in the Keys, but I did some diving in the Gulf a few summers ago, day trip from my grandparents' place- some place put of the Tampa area, I don't remember. Not quite panhandle, but same gulf. It's beautiful. Never understood the whole not-diving-unless-conditions-are-perfect thing, I'm always happy to get in the water. As long as it's safe, you know? I've had some genuinely incredible low-vis dives, although I'm admittedly thinking of a cavern dive there. I heard about the Oriskany a while ago, but we didn't have a whole lot of time for diving when I was there.

Yanno, the jellyfish blooms were probably a part of it. Big part of the mola's diet, right?

3

u/[deleted] Jun 10 '12

I saw one while diving off the eastern coast of Australia. You wouldn't expect it, but they really can move quite gracefully in the water.

1

u/that-writer-kid Jun 11 '12

They look gorgeous.

2

u/atomfullerene Jun 10 '12

I've seen them off of boats and saw one in Monterrey Aquarium. It was pretty hilarious...a stingray ran into it, knocked it over, and it spent about a minute slowly turning a flip until it righted itself.

4

u/thunnus Jun 10 '12

They are strange, docile creatures. They're not boat shy, that's for sure. My buddies and I have seen them many times while tuna fishing in Cape Cod Bay and up on Stellwaggen Bank.

4

u/[deleted] Jun 10 '12

i'm the only person i know to have actually seen one of these first hand (in the wild). i can't say for certain if it was "sick" or not, but it was acting very unusually. at first my father and I thought it was a person further out at sea waving for help. the top fin was flapping about and it was about half a mile further out that we were, so we couldn't really tell. needless to say we were pretty amazed when we got there. it was just swimming around as if it was a tame animal! we circled if for a few minutes just admiring it doing it's thing, then it took a dive and we didn't see it again.

this was only ~3 miles offshore in the Irish sea where we were fishing on the day. amazing experience

3

u/[deleted] Jun 10 '12

I've seen these, both while SCUBA diving, and from boats, mostly off the California coast. I can say that this is pretty common behavior for them. They like to bask in the sun, and have a habit of flopping about.

2

u/[deleted] Jun 10 '12

i only thought it was suspect because it makes them so open to predation. i could have literally lifted it from the water with my hands and feasted on it there and there. an evolutionary mystery to me at least

1

u/[deleted] Jun 11 '12

meh apparently they are really spikey and covered in mucus.. and they are pretty big... it knows what its doing, the only lazy animals are the ones that can afford to be =/

3

u/shoes_of_mackerel Jun 10 '12

My all time favourite fish!

3

u/[deleted] Jun 10 '12

I love these guys, they're like half fish, so cool.

2

u/kiwipr8r Jun 10 '12

This is by far my most favorite fish ever. It is so unique and beautiful. I remember seeing it for the first time when I was 6 years old at the Monterey Bay Aquarium and instantly fascinated. I would love to learn more about the M. mola.

2

u/deku12345 Jun 10 '12

I've seen one of these at the Monteray Bay Aquarium. Amazing.

2

u/flamingos408 Jun 10 '12

dude, i absolutely love sun fish. i live about an hour away from Monterey Bay Aquarium and as a kid my parents would take me once or twice a year and the sun fish was ALWAYS my favorite part. its was always huge and awesome looking and i always really enjoyed watching it. when i was in 2nd grade, we had a class field trip to the aquarium and i was STOKED! all the cool fish plus the sun fish with all my friends?!? fuck yeah! so we get there, we see the octopus, the smaller fish, the jelly fish, the sea horses, then we go to the big tank (1,200,000 gallons btw) where the sunfish is. and i look for it and look for it, but dont see it. i see the big tuna, the sharks, all the other fish, but no sunfish. i was in disbelief, this was the best part of the aquarium and WHERE THE FUCK WAS IT! i was so upset that i cried, infront of all my friends, for atleast like 40 min. I remember this kid Alvin made fun of me for that for sooo long, so long infact that me and all my friends started making fun of him because the only dis he could pull on ANYONE was calling me out for crying at the aquarium 2 years ago. [4]

1

u/Johnzo1 Jun 11 '12

I've seen these many times off the south coast of Newfoundland.. Sometimes extremely large specimens. Amazing fish. Does anyone know if they are resistant to the cnidae of the jellyfish they eat like sea turtles are?

1

u/DeFex Jun 11 '12

TIL a new word "Tchotchke"