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Dive Dry with Dr. Bill

#647: The Mutual Eating Society

I am a carnivore... well, actually an omnivore. I eat meat... but I also eat vegetables (with the exception of asparagus and peas). I have friends who are vegetarian and vegan, and I wouldn't criticize their food preferences any more than I'd want them to criticize mine. As a biologist, I believe a mix of different foods is best. However, I have cut down on meat over the years and try to eat vegetarian twice a week. There are good ecological arguments for vegetarianism. Anyone familiar with the trophic pyramids from high school biology class should realize that you can feed more people with plants than you can with herbivores or carnivores in a given system.

However, I don't accept the "moral" or ethical arguments for vegetarianism with one exception, the horrible manner in which we treat many animals destined for our dinner plate. As a marine biologist of nearly 50 years, with a focus on munching and mating in ecosystems, I have observed critters crunching down on seaweeds and other critters as well. Back when I taught ecology, I referred to this as "the mutual eating society." Ecosystems involve photosynthetic organisms like giant kelp to capture energy from the sun and provide food for the plant eaters (aka herbivores) such as abalone and many other snails. These are eaten by predators such as sheephead who in turn are munched on by higher order predators such as sharks and sea lions.

A marine or terrestrial ecosystem based simply on primary producers who photosynthesize and herbivores which graze on them would be very simple and ecologically unstable. Grazing animals in a greatly simplified artificial habitat with no competitors or predators does not a healthy environment make. Ecosystem stability is often a function of the biodiversity and complexity of the food webs involved in them. I am constantly reminded of these principles when I dive in our waters to observe and film "the wild life." Afraid the other "wild life" on Friday and Saturday nights is well past this old geezer!

On a few recent dives, both day and night, I was offered many more examples to substantiate this. During sunlight I watched as diving birds known as cormorants swam through the water chasing after blacksmith and baitfish. Barracuda and kelp bass joined in the feast. Not a single one stopped at the salad bar. It was all about the concentrated protein in fish flesh. Even the common opaleye proves this example. In warmer waters further south in their range they are almost 100% plant eaters. However, here in our waters they ingest animal protein as well in the form of small encrusting invertebrates since their energy needs are higher in our cooler waters.

But it is on my night dives that the predatory nature of King Neptune's realm is often best displayed One of my favorite talks that I give to dive clubs through southern California is "Munching & Mating: The Night Shift." This video-based presentation derives from hundreds of night dives, the vast majority at Casino Point, during which I film lots of munching thanks to the nocturnal predators that come out of hiding during the dark.

Over the years, my night dives have allowed me to film kelp bass and morays taking blacksmith and kelp surfperch. In several cases morays unfamiliar with California Fish & Game rules tried to take garibaldi. That would be a costly meal, but the eels seemed to have second thoughts and missed. Footage of kelp bass grabbing smaller fish and swimming off with them in their mouths may seem cruel... but it is the natural way of things. Of course few humans think of the origin of their food flesh when it is purchased at Vons. For that reason, I have no qualms with those who fish or hunt for their food. They are part of the ecosystem (albeit at huge technological advantage over their prey). Hunting or fishing for "sport" is a completely different issue though.

One recent dive with friends resulted in an unusual example of predation I had not previously captured on film. Years ago I watched as a moray hammered into a hole in the reef. I found a small crevice I could look through and saw that there was an octopus inside holding a kelp crab in front of it for defense against the hungry eel. The moray eventually gave up and backed out of the hole. On my recent dive I turned a corner on the reef and just to my left was a moray reaching out and snagging an octopus out in the open. I pressed the record button on my camcorder but due to the time lag, it started recording after the moray had captured the octo and turned away from me to drag it into its lair.

Don't feel sorry for the octo though. I've watched those predators disassemble prey as well. On the back side I once filmed an octo dragging a southern kelp crab up and over the reef to its hole. It whipped out its arms at hungry sheephead and kelp bass who followed it, hoping to make predator or prey a meal for them. Once it dragged the crustacean into its home, it tore it limb from limb. On one dive an octo jumped on top of another kelp crab, but the crab wisely pinched it and the octo fled without a meal. I have seen crustaceans get revenge when a lobster dragged off a dying octopus for its dinner.

So don't feel sorry for these critters. With the exception of photosynthetic plants and seaweeds, all organisms eat others whether it be a snail tearing off chunks of seaweed or a sheephead crushing the snail's hard shell in its mouth. Heck even plants like the Venus' fly trap and pitcher plant are known to consume the flesh of insects. As I said, it is "the mutual eating society." One may choose to be an herbivore, a carnivore or an omnivore. We all need to munch on something to sustain us. However, I will not attempt to attribute any moral high ground to any of those choices. I do understand those who criticize the way in which some of our animal food is provided, but even vegetarianism involves the transformation of often complex natural ecosystems into simplified agricultural fields. Put that in your stomach and digest it!

© 2015 Dr. Bill Bushing. Watch the "Dive Dry with Dr. Bill" underwater videos on Catalina Cable TV channel 29, 10:00 AM weekdays and on Charter Communications Cable channel 33 at 7:30 PM on Tuesdays in the Riverside/Norco area. You can also watch these episodes in iPod format on YouTube through my channel there (drbillbushing). Please help me climb out of self-imposed poverty... buy my DVD's (see this link). Yes, take Dr. Bill home with you... we'll both be glad you did!

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Moray dragging blacksmith into hole and kelp bass with blacksmith in its mouth;
octopus attempting to capture kelp crab and octopus dragging blacksmith off for dinner.

This document maintained by Dr. Bill Bushing.
Material and images © 2015 Star Thrower Educational Multimedia