Dive Dry with Dr. Bill

#231: Crab Cocktail... Without the Sauce!

Last week I promised to keep my focus on the Munching "M" word for a few weeks, and I am a man of my word. No finger crossing behind this diver's back! There will be no talk of "romance" or that other "M" word from my lips... er, my pen... this week. However, no promises about the future. Heh, heh, heh. So on with this week's tale of our undersea world. Ecology focuses on the relationships between different species in the environment, and one of the critical relationships involves munching. After all, this IS the mutual eating society.

A few months ago moderate NE winds had SCUBA Luv's King Neptune heading for the windward side of the island. Of course since the winds were hitting the Channel side of the island, one could consider the backside to be in the lee of the wind that way. It was a good choice, and we ended up diving Salta Verde Point and China Point. I entered the recovering kelp forests at China Point to poke around in the rocky reef there on the second dive of the day. Conditions were great for this coast, and the marine life on "the other side" is just different enough to make it an interesting change of pace.

On this dive I had a second buddy, not just my usual pony bottle. A young harbor seal was quite curious about me and kept swimming past to get a better view of this strange creature with the underwater camera. Unfortunately, it kept enough distance from me so I was unable to get good images and make it the subject of this week's column. While harbor seals on the mainland often approach divers closely, here they seem to be a little more standoffish.

I was working my way around a rock the size of your usual Avalon apartment when I noted an octopus begin to move off towards shelter. It was moving somewhat awkwardly, which suggested something different was happening and that piqued my curiosity. I'm always on the lookout for unusual behavior to film, whether it be "M" or "M" (or "M" & "M" as happens in some species!). As I inched closer with my camera rolling, the octopus was hunched over something with the webbing between its eight arms hiding whatever was trapped beneath. Slowly the arms moved and the situation started to become clearer. Out from under the webbing popped the bright red claw of a fairly large crab, and the claw was no longer attached to the rest of the crab!

Yes, this octopus had successfully captured a nice crab to munch on. The rest of the crab's body remained hidden under the cephalopod's mantle. As I watched and filmed, it was obvious from the movement of the body that the octopus was manipulating what was left of the crab so it could tear it apart with its beak, and get at the tasty innards. Reminded me of someone eating an East Coast lobster claw with a lobster cracker. The octopus showed no reverence towards its prey like that we are told Native Americans and good hunters show towards the game they hunt for food. It just kept tearing away at the deceased crab, its only thought to stuff as much of the tender meat into its belly as it could. Sounds like me at an all-you-can eat buffet.

Of course this vicious onslaught tore the crab apart, allowing various savory juices to escape from under the mantle and draw other predators interested in a free lunch. These included sheephead, garibaldi and kelp bass. Individuals of all three species began to circle the feeding octopus. It must have realized it might be forced to share its feast, or become dinner itself. Being a bit selfish thinking and only of its own survival, it began to drag the crab's carcass across the boulders to its shelter hole. I can relate to this since I occasionally hunch over a nice blueberry pie or barbecued flank steak, selfishly protecting it from other potential diners. After all, I'm a growing boy (with a "shrinking" wetsuit)!

The octopus had a little trouble dragging its meal through a crevice between two boulders. Although the cephalopod's soft mantle allowed it to easily squeeze through , the hard exoskeleton of the crab didn't pass quite so easily. The octopus finally dragged it through the crevice and ambled across the next boulder with several of the fish following it, nipping on its tentacles and exposed parts of the crab. Our eight-armed wonder made it to its shelter hole on the other side, and so did I with my camera rolling. Unfortunately for it, the octopus had once again miscalculated. It could not pull the large crab into the hole, and it remained stuck in the opening as the eight tentacles tried to manipulate it to get it through the opening. These efforts were not successful, and the sheephead finally had a clear shot at what was left of the crab while the octopus kept itself safe within its shelter.

I can't believe that some of my readers prefer the violence of munching to a little tender love-making by the critters of the deep. How can one possibly be offended by the mating orgies of our local sea hares, or the graceful courtship dances of our surfperch, or the casual but synchronized casting of sperm and eggs into the surrounding waters by sea urchins? I can see why one might be a bit squeamish about shark mating, since the males are often pretty rough with their lovely ladies, biting them to immobilize them and sometimes killing their potential mate. That really cools off their ardor. Can you guess what the subject of next week's column might be? Well, I'm not telling!

© 2007 Dr. Bill Bushing. Watch the "Dive Dry with Dr. Bill" underwater videos on Catalina Cable TV channel 49, 10:00 AM and 5:00 PM weekdays. Please help me climb out of self-imposed poverty... buy my "Munching and Mating in the Macrocystis," "Great White Sharks of Guadalupe," "Calimari Concupiscence: Mating Squid, " "Playful Pinnipeds: California Sea Lions," "Belize It or Not: Western Caribbean Invertebrates, Fish and Turtles," "Gentle Giants: Giant Sea Bass" or "Common Fish and Invertebrates of the Sea of Cortez" DVD's. Yes, take Dr. Bill home with you... we'll both be glad you did!

Octopus mantle covering meal, octopus with claws; octopus trying to pull crab into hole,
crab carcass at opening of octopus' hiding place.

This document maintained by Dr. Bill Bushing.
Material and images © 2006 Star Thrower Educational Multimedia