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Aggregating Anemone Catching A Red Crab

Mike Spinak

pro member
Last week, my Sleeping Sea Lions photo provoked some discussion of planned photography versus spontaneous photography. This provoked me to now show one of my pictures which is closer to the spontaneous end of the spectrum than the planned.

In this case, I was out at the local tidepools, photographing many things, but mostly nudibranchs and anemones. I was finishing up for the day. I was way out at the further edges of the low intertidal zone. The last rays of the sun were fading. More importantly, the incoming tide was nipping at my heels. I had delayed leaving for so long that the incoming tide would soon overtake me, if I didn't leave immediately. I didn't even have time to pack my equipment; I was just carrying it unpacked in my hands... something I try to avoid doing, in a hard, jagged, uneven, wet, slippery, puddle spotted landscape, to avoid hurting myself and to avoid damaging my equipment.

So, I started to head back to the cliffs, with my hands full with my camera gear. I only got about 10 or 15 feet, when my shooting partner and I saw this aggregating anemone catching a red crab.

I see it fairly often, but it remains an amazing thing to see. To say that anemones intuitively seem slow and ungainly is an understatement. People often don't realize that they move at all. Indeed, people often don't realize that they are more animal than plant. Yet, anemones are capable hunters, and crabs are a staple of their diet. As in this case, they often catch prey considerably larger than themselves.

Additionally, the fascinating foreignness and unfamiliarity of these creatures adds to the interest. Not only is it a life and death struggle, but it's a life and death struggle between a crustacean and cniderian... one creature seemingly very different from ourselves, and the other creature seemingly incomprehensibly unlike ourselves.

I figured that I had until the next wave came in, probably within the next fifteen seconds, before the opportunity for the shot would be lost. I worked remarkably fast for me, considering that the camera was tripod mounted, the lens manually adjusted focus, and everything manually exposed, with off-camera flash. (The tide did, indeed, come in within about 15 seconds, and the opportunity was lost.) So, the results are rather sloppy, to say the least. I'm not very happy with the picture neither technically (especially the flash) nor compositionally, but... for me... the spectacle supersedes the photo's deficiencies, in this case.

I hope you enjoy it.

280315681_ec3806943d_o.jpg
 
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Angelica Oung

New member
Wow. I had no idea anemones could attack a crab that size! Did it get away? Great shot.

I can't help but want to see if you took any more of the aftermath. It would make a fascinating (if grisly series).
 

Asher Kelman

OPF Owner/Editor-in-Chief
So Mike,

Which would you say is the most primitive and the most advancecd?

and who eat the anemone?

This is out of this world beautiful and frightening.

Asher
 
SUPER SHOT Mike.... Love it! Are you sure the anemone has a munch and is not taking a ride? I never heard about them eating anything bigger than shrimp.

Asher, the anemone (flower of the sea) is a most interesting live form. There are more tha 1000 types of sea anemone. It is a diverse species and found throughout the oceans. They literally harpoon (stinging cells) their prey to paralyse them and can reach a size of 1 inch to 6 feet across. I think most anemones are scavangers. But there are predator anemones as well. Then there is a third which are symbiotic anemones, trading photosynthesis for fertilizer. Some hermit crabs put sea anemones on their shells where the hermit crabs live for camouflage. Some ocean life such as clownfish do not trigger discharge of sea anemones' coiled tubes and can form associations with sea anemones. Usually they stay local, but if they move they have a speed of 3-4 inches per hour, or, they take a ride on a crab.

The crab is protected by it's shell Mike, the anemone stingers can not even penetrate human skin.

Some fish do eat anemones, and of course the seaslug has a munch on them.

Courtesy of Australian Museum Onlinem, Brian Plankis:

http://www.seaslugforum.net/showall.cfm?base=spurneap

m14649a.jpg


Anemone anatomy ( say it ten times fast grins)

anatomy_anemone.jpg
 

Mike Spinak

pro member
Nill,

Thank you.
________________________________

Angela,

Thank you.

They even attack bigger crabs than that.

As I explained above, it wasn't possible to get any more shots of this. In my opinion, it is unlikely that the crab got away. You can see, here that the anemone has a firm grip on the crab, and that the crab is in a position where it can't defend itself, grab on to anything, or make an escape.
_________________________________

Asher,

Thank you.

It's hard to say which is more primitive and which is more advanced. It depends upon your criterion, and how you look at it. Such questions and answers can be surprising, such as recent discoveries that humans are genetically rather simple in comparison to many organisms of the world.

Anyway, by our usual ways of looking at things... central nervous systems, sensory organs, etc... the crab is the more advanced.

In my area, nudibranchs (sea slugs) prey on small anemones.
__________________________________

George,

Thank you.

Yes, I'm certain that this aggregating anemone is preying upon this red crab, not hitching a ride. Look it up. Crabs... red crabs, chocolate porcelain crabs, shield backed crabs, etc... are a large part of the diet of aggregating anemones. There can be no mistaking it: I also find them further along in the stages of digestion, and find them regurgitating pieces of shells.

You will notice that this anemone is not trying to employ a stinging technique to catch the crab. It has clamped onto the crab with its mouth muscles. It will let the crab struggle to exhaustion, then turn its stomach inside out, outside of its body, surrounding the crab. It will partially bring it into its body, softening the shell with digestion, and crushing it with its stomach muscles. It will "suck" the digestion-putrified flesh out of the shell, and spit out the shell remnants.
 
Yes, I'm certain that this aggregating anemone is preying upon this red crab, not hitching a ride. Look it up. Crabs... red crabs, chocolate porcelain crabs, shield backed crabs, etc... are a large part of the diet of aggregating anemones. There can be no mistaking it: I also find them further along in the stages of digestion, and find them regurgitating pieces of shells.

You will notice that this anemone is not trying to employ a stinging technique to catch the crab. It has clamped onto the crab with its mouth muscles. It will let the crab struggle to exhaustion, then turn its stomach inside out, outside of its body, surrounding the crab. It will partially bring it into its body, softening the shell with digestion, and crushing it with its stomach muscles. It will "suck" the digestion-putrified flesh out of the shell, and spit out the shell remnants.

Fascinating!
 

Paul Bestwick

pro member
[/QUOTE] It will "suck" the digestion-putrified flesh out of the shell, and spit out the shell remnants.[/QUOTE]

I have seen a similair technique employed by teenagers as I have walked past Mc Donalds.

amazing photo & I thought they were more plant than animal (not the teenagers)

Cheers,

Paul
 

Josh Liechty

New member
The picture is quite fascinating, though I find the explanation behind the events even more interesting. Even after you explained the technical faults, I could hardly see any of them - the event in the photo is very striking.
 
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