Wednesday, September 22, 2010

Anatomy of an electric ray

I love my job. Sometimes I just get to participate in (or watch) cool stuff. As was the case a week ago, when I learned that we were going to be dissecting an electric ray.

This electric ray had been brought in by a fisherman, who didn't want to eat it or let it go to waste. So we decided to hold a public dissection, so that we could learn more about it. We also preserved some of the pieces for our collection, to be used for later research or teaching.

Electric rays are slow-moving rays that live off of the pacific cost, in cool waters. They don't have a stinger, but do have a specialized organ that produces electricity, which they use to capture food and defend themselves.

In this picture you can see the two-chambered heart, center, at the right most edge of the cut. Below that (center) is the stomach. To either side of the stomach are two very large livers. Like all sharks and rays, the electric ray lacks a swim bladder and depends on the oil reserves in the liver to help maintain buoyancy. The large green ball near the upper liver lobe is the gall bladder.

This is a nice close-up of the electric producing organ. Basically, it is little more than coin shaped muscle stacks. Since muscles produce electricity, the arrangement of muscle tissue in this configuration helps optimize the amount of electricity produced in the area. By having an organ on either side of the body, the electric ray can stun prey trapped between the two sides of their fins.