Monday, April 25, 2005

Mammals suck

...their mother's milk.

This thing was born April 24 at about 8:30 am here at the station.

It's a newborn Harbor Seal Phoca vitulina, about 6 hours old, suckling its mother. There is a 6" section of umbilical cord hanging off the pup's stomach. The pup is roughly 2 to 2.5 feet long here.

Thursday, April 14, 2005

Intertidal critters might be overdesigned

In the rocky intertidal we find a plethora of animals and plants which appear to be severely over-designed to withstand the pounding forces of breaking waves. Barnacles might be one of the best examples of this over-engineering. They build little calcium carbonate fortresses around their body, and these are anchored to the rock. The shell of the barnacle is strong, sometimes stronger than the rock tow which it's attached.

For example, this is a shell of Balanus aquila which I found lying on the beach here in Monterey.

It's a big barnacle, usually found in the low intertidal and subtidal zones. This individual was long dead. What's unique here is that I found the entire shell, intact, and free of the rock. It was removed by something, perhaps a small boulder rolling around, and rather than being crushed, it simply broke free from the rock. We're not dealing with wimpy sandstone or mudstone rock either, this barnacle shell was ripped right out of the granite found around Monterey.

The underside of the barnacle shell is just granite. It's hard to imagine just how this shell and bit of rock broke free of the rock without the shell being crushed, but it happened. This is clearly a case where the organism (its shell in this case) was extraordinarily over-designed for the situation in which it was living.

Wednesday, April 13, 2005

Retiring old parts

My SnailCam camera housing has been deployed in the intertidal zone here at Hopkins for over two years. For the last year and a half, I've had an infrared lighting systems for recording pictures at night. Since I've now decided to undertake a new project with the SnailCam setup, I pulled the camera and housing out of the field after more than a year of non-stop deployment with no failures.

Pictured above is the infrared light source. It used a set of Agilent Technologies HSDL-4220 30 degree infrared LED's (875nm wavelength). The LED's were set up in 5 banks of 4 LED's arrayed in series with a 10-ohm resistor, with each bank wired in parallel with the others. The whole setup used about 2 amps at 7.5 volts DC to give each LED 100 milliamps. These supplied enough light at night for the low-light sensitive CCD camera to supply a bright clear picture under the darkest of conditions. (see more info here: SnailCam project )

The LED's were mounted in a machined Aluminum ring, and the wiring in the backside of the ring was waterproofed using normal 2-ton epoxy. As I said, this arrangement was in the field for 1.5 years before I finally started to have problems.

This picture is of the same ring of lights, when I pulled them out of the field. I believe that the brass bolt I used as a strain relief set off an electrolytic reaction which ate away at the aluminum ring.

At some point, water also began seeping in along the wires, and led to electrolysis at another point on the aluminum ring and somehow created the expansion seen in this second picture.

As bad as this looks, I was amazed to find that two of the five banks of LED's still worked when I hauled it back to the lab. After getting 1.5 years of service out of this setup, I won't hesistate to use this general method again, though a non-conductive plastic ring mount for the LED's might be a nice modification.

Monday, April 04, 2005

You can never have enough temperature measurements

Slightly pricey stuff, but if you need 10's or 100's of thermocouple channels, this place has the goods.