why do they do that ?

[farsidefan1]

Sorry, venting about something I just had a bellyfull of with someone else. I should not have let it spill over. My apologies.

 

[Peter_C]

Because frisbee is a fun game? Seems this one was doing a pretty good job of tearing the Mola apart.

A few years ago I was wakeboarding at the Delta and saw a log I was going to ollie. As I cut out the log not only moved, but threw a salmon at me! Yup it was a sea lion and narrowly missed me with the salmon. Much like a cat, they do enjoy playing with their food, except maybe they just enjoy playing with Mola's as they are an easy target.

 

[chillyinCanada]

Ya, as long as you don't come home and find a dead mola left on your porch as an offering to the parental unit.

 

[GregSaiz]

Had the pleasure of seeing two live Molas in Monterey Saturday and the bottom was littered with scores of finless dead or dying ones. Of the living, one was followed by a school of wrasses, presumably cleaning. The other was being chased by a sea lion. I'll say one thing, mola moved surprisingly fast while evading fate as frisbee.

Here's an entertaining TED talk on the amazing Mola: Tierney Thys swims with the giant sunfish | Video on TED.com

 

[KRL1973]

I have also heard that it is feeding, not playing or malice. The sea lions eat what they can and then continue feeding later after the bottom dwellers have a go. I wasn't aware of poisoness skin, but that explains alot about why they don't eat them entirely right from the start.

 

[divad]

Um, maybe let's take it down a notch?

OK. What about those killer bunnies?

 

[farsidefan1]

Don't mess with the bunnies, I saw the movie!

 

[g1138]

I recently heard a theory to explain this behavior which makes sense to me, but I want to talk with some more marine biologists before accepting it.

First, I was told that the skin of Mola's is poisonous to most predators--especially Sea Lions. So, according to this theory, Sea Lions as a species have developed a survival mechanism of ripping the fins off the Mola's and then letting the body sink to the bottom where the sea stars can come feed on them and dissolve the poisonous skin. After the skin has been stripped, the Sea Lions then go down to feed on the stripped carcass.

You'll have to admit that it is a bit of a stretch to attribute simple malice to the Sea Lions as an explanation for this behavior. Pure malice is rarely found in nature--except in humans. (But then how do we explain Orca's batting Sea Lion pups around?)


Bruce

I'm curious as to exactly who/where you hear that?

I think that's a big stretch of a theory. If it was purely for food then why waste the energy flinging the mola across the surface. Why not just bring it down to the bottom after ripping it's fins off.

There's also the issue of finding out that sea stars digest the poisoness skin to allow easier consumption. How exactly did a sea lion figure that out, and how did that translate to the sea lions as a species learning that behavior?

Even if that were the true case, the energy expenditure and time spent waiting just for a mola meal isn't a good tradeoff in my mind. Speaking of time, ever try to bake cookies without a timer? How many times do you open the oven? How many times would a sea lion have to dive down and knock sea stars off just to see if their mola meal was ready? Ever try to knock pepperonis off a pizza with your nose?

To further put a nail in this theory, the general consensus about neurotoxins being present in molas is that there isn't a general consensus. It's disputed. But what support for toxins being present states that it's in the organs, not the skin. The skin is also very tough, being composed of a lot of collagen. Again talking about energy; the energy it takes to eat and digest VS the energy gained is not advantageous to consider the mola as a primary source of food.

From personal experience, of the dead molas I've seen, I've only to date seen one where the body was apparently consumed. (ie. teeth marks impressions around the torn body w/ a huge chunk missing; very similar to the picture posted above)
But it could have also been continuous chunks torn and left floating.

As for pure malice, cats usually act aggresively when introduced to a new kitten or puppy. There's a Chromis who bully's another Chromis in MB Aquarium's Bycatch exhibit to the point that the bullied one is always hiding.
A perch is constantly pecking at a skate in the Deep Reef exhibit as well (you could see the sores after a day before we pulled it).

For sea lions, I think it's more entertainment than malice though. Similar to cats kill-playing mice but not eating them.

 

[fisheater]

I watched a sealion eat the whole Mola mola at the surface a couple of week ago in Monterey. So, it does happen.

I also found four dead, finless ones on the bottom. So, figure.

 

[GregSaiz]

Could it be as simple as the sea lions just think the fins taste good? I don't see any fins lying around so I assume they get consumed, not discarded?