Tuesday, August 5, 2008

Day 2. Observations: Perwinkles & Land Snails (Kris Pandeli)

Monday: August 4th, 2008.

Weather: sunny

Location: Lovells Island


Observed the periwinkles at the tidal pool at Lovells Island, took picture, took measurements, recorded colors, shapes, stripes, texture and other examinations of the samples we collected. Then we moved to the inland snails of the island to collect yet another diverse sample of snails and take the same approach as stated above. Many approaches were taken by students to group these snails and snail shells by their visible traits; mostly their color stripes and shape. Below there will be a better description by steps and procedures along with photos to make the descriptions more clear.


This time I was better prepared as I brought with me a variety of tools to examine the species. The tools include: pen, pencil, paper, ruler, digital camera, magnifying glass, binoculars, and the guide book.

Observations and Data:


First I will describe the periwinkles sampled form the tidal pool behind Lovells Island. About 30 to 40 ft. into the tidal pool me and fellow students pooled out a few different sizes of periwinkles ranging from .5 cm to 3cm wide in diameter. The first one I examined was 1.5 cm in diameter. On the tip or the cone it was a light brown color (area of 3-4 mm), with the major part of the shell being a dark brown/black color taking up (area 1 cm). The opening or the mouth of the periwinkle is a very bright brown about 1-2 mm all around.( See the sketch/See photo).

The second periwinkle was about 2.5 cm in diameter. Light brown all around only with 2 mm of white tip-top. The shell appears damaged and repaired/healed as you can see small cracked stripes. The texture of the surface is harder not as smooth as the younger/ smaller periwinkles. The coloration and the texture of the shell can be due to the fact that this could be somewhat older and more beat up against rocks and salt.

Another third sample was a few old periwinkle shells by the shoreline. They were 3.5 cm in diameter 1. lighter color probably due to deterioration and bleaching 2. Cracked shells and stripes 3. Light brown/yellow color close to the opening of the shell or the mouth.

LAND SNAILS/Comparison to Periwinkles

My first find happened to be of the two most common land snails found at the island. The Yellow snail with a black ribbon and the dark brown snail with the yellow/light brown ribbon. The brown snail also has the brown lip and you can also see the yellow snail with the white lip, and they both are eating at the green leave (Refer to the pic). They were mostly found stuck below the leaves of small trees. They were stuck underneath of the leaves because that’s the way they consume the leaves or maybe because they are less visible to predators, like the predatory birds. Fist of all the main difference that stuck out at me was that the land snails were rounder and not with at pointy tip like the periwinkles. Their shells were also smoother and they were more diverse in colorations. The color combinations included, yellow, brown, light brown, white, and pinkish. To my conclusion, I decided that these were still the same species (1 species). The second difference from the periwinkles was that the land snails when they moved you could see the whole lip, ears and head sticking out. The land snails moved faster than periwinkles as they also seemed to produce more of the slimy/slippery saliva. The periwinkles moved a lot slower and one almost could never see the lip.

Habitat: When we pulled the periwinkles out of the water they seemed to get dry and not moving slower than anything I have ever seen. They seemed like they did not like the heat of the sun. They felt more comfortable in the water. But the land snails even though they too were found in some wet/ humid areas they seemed more relaxed than the periwinkles out in the sun, and they moved a lot faster as they where slipping away from our hands. With our class discussions and listening to professor Berman the theory was that these two species could have evolved from one another.

The end of our collections we collected many shells of dead land snails. These shells differed in colorations and texture. Many students were chosen to try and group them by color and texture and many selections led the four main groups as seen in the photos below.

Today the weather was great and the trip was amazing. A little too long of a field trip but we all made it through. We all went home with more data and samples to write about. Today’s observations were a lot clearer and fascinating.

Enjoy the short video clips below.

~Kris Pandeli

No comments: