Us: 1, Barnacles: 0!

Hello All.

Tonight marks the hurtle over a gigantic milestone in gooseneck barnacle research. From the basement of Mabel Smith Douglass Library, Brian and I finally conquered the barnacle JPEGS, capturing their size in a pixel-to-pixel ratio using the the ruler tool in the Photoshop program. We measured the theoretical, tangential diameter of the glider at the point closest to the sample barnacle, and then measured either the height or the width of the sample barnacle itself. Pretty simple.

The tricky part for us was figuring out how to successfully convert pixel measurements into millimeters. Luckily, there are conversion tools floating around the web, waiting to be found by a pair of eager researchers like Brian and myself. We fished for a bit, and decided to go with a .org site (...based on the mythical legitimacy of the .org genre of websites). The website we chose can be found here. Just put in your pixel measurements, and voila: mm, cm, km, whatever.

By using a proportions formula, that we hope we've set up correctly (...remember, we're biologists, not mathematicians!), we scaled 2 barnacles and a large cluster situated near the front segment of the glider, on the "R" side of the vehicle.

Here is an example of the formula we used (all measurements in millimeters):

Theoretical Glider Diameter/Actual Glider Diameter = Actual Barnacle Height/Theoretical Barnacle Height

"Theoretical" values represent the pixel measurements taken from the JPEG converted to millimeters. The value in bold was the one we were searching for.

We were surprised by the accuracy of the conversion. Our first test subject, Barnacle 1, measured a height - from first visible point of peduncle (stalk) to tip of cirri (featherlike feeding apparatus) - of 43.14 mm after conversion.

lepas anatifera

Lepas anatifera

Our barnacle books have told us that a full grown Lepas anatifera can clock in at around 40 mm! So, Barnacle 1 can be assumed to be a full grown parasite, secreting disulfide fluids with adult-sized vigilance and malice.

The cluster, comprised of 15 visible barnacles, measured 90.58 mm from top to bottom, slightly off-kilter, but helpful. The cluster takes up approximately a little less than half of the glider's diameter (212. 725 mm).

Our third specimen, Barnacle 2, was the sample from which we measured the average height and width of the capitula (flowerhead, or plated body) of the barnacles. The height of B2 was just shy of 30 mm (28.22 mm), and the width was 24.11 mm. The measurements for B2 are interesting because this barnacle rests on (or rather sinisterly cements itself to) the frontmost ring of the vehicle, the width of which is only 15 mm across in actual measurement. So, the capitula of Barnacle 2 is actually both wider and taller than the ring it rests on. The height of B2's capitula (28.22 mm) compared with the total height Barnacle 1, is about half of B1's entire length from tip of stalk to tip of cirri. Just interesting.

The specific measurements themselves, of course, are of vital importance. But, the main point we're trying to make here is: most of barnacles on the glider are full-grown, which means that they were probably residing on the glider itself for around 2 weeks before the photos were taken in the Azores. They also fit within size range suggested for a full-grown barnacle of the Lepas species.

Thanks, Sage, for showing us how to use the Photoshop ruler tool!

Goodevening everyone,

Amanda and Brian

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3 Responses to “Us: 1, Barnacles: 0!”

  1. Antonio RAMOS Says:

    Just a msg to say

    YOU: 1000000 - BARNACLES: 0

    I ve been relooking the biblio using lepas anatifera and looks the paper and abstract found (the last paragraph of the abstract:
    4 cm total size (peduncule + capitulus) in 17-23 weeks !!!!


    Goldberg, H & Zahradnik, JW (1984)
    The feasibility of the gooseneck barnacle Lepas anatifera as a candidate for mariculture
    Journal of Shellfish Research. Vol. 4, no. 1, pp. 110-111.


    The acquisition of seed and the subsequent suspension culture of the gooseneck barnacle Lepas anatifera was investigated. Lepas anatifera successfully colonized the cultch (oyster shells, wooden dowelling, and rubber) that was developed at two locations off the western coast of Vancouver Island. The experiment indicated that growth rate may be site-specific and that areas of a high phytoplankton: zooplankton ratio may be a detriment to growth and timing of sexual maturation. At the densities studied, survival appeared to be proportional to density. Capitulum growth and weight gain were significantly greater for barnacles that were protected from predation within lantern nets than for those grown exposed on lines of oyster shells and wood dowelling. The mean total growth (capitulum plus peduncle) exceeded 4 cm in length within 17 to 23 weeks.

  2. Dan Says:

    Painting a chequered pattern of known size (like in automotive crash tests) on the glider before deployment would have helped the measurements?

  3. Phil Slattery Says:

    We have lots of flotsam and jetsam that washes ashore on our beaches here in the Gulf of Mexico. A lot of it is covered in goose barnacles usually about an inch to half-inch or less in length (including the stalk). Is there anyway to judge how long an object has been in the water by the size of the goose barnacles on it? Is there a normal or average growth rate? I see by the studies at Vancouver Island, goose barnacles' growth may vary according to their diet. If you don't have this information, can you refer to someone who might? You can see the type of environment we have by visiting the park website, which I have listed.

    Phil Slattery

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