Lovell Island is similar to Peddocks Island in terms of
living organisms and also habitat. But this time, the beach was less rocky and
somewhat sandy. Also the boundary of terrestrial region and water was not
accurate in Lovell Island beach unlike the Peddocks Island. The reason why
there are less cobble in Lovell Island can be the conversion is still in
progress there. I guess as time goes by, the Lovell Island will become a cobbled
beach. Even similar organisms exist in this Island such as periwinkles, crabs,
rockweeds, snails, barnacles, tunicates and sea lettuce, this time, the amount
of those organisms was surprisingly enormous compared to other habitats.
However, although there are huge amount of periwinkles, comparatively there
were not different kinds of it. Almost all of them were gray-brown periwinkles,
but there were rarely yellow and white periwinkles. I guess they were all the members
of the same species.
On the other hand, we saw some snail shells that have
different colors on the rocks away from the sea. When we walked into the woods,
we saw same kind of snail on the trees. Since we didn’t see those shells in the
low tide region but many of them in the terrestrial region, they should be a
different kind of snails. I guess it was “Grove snail (Cepaea nemoralis)”. Most
prominent predators of these snails were birds and mice according to the study
of Rosin, Olborska and Surmacki in 2011. They explained the preferences of
birds and mice and the results showed that mice choose small individuals
because they use their teeth to break and large shells require more time and
energy in order to extract the soft tissues. However, birds break Grove Snails open
by repeatedly knocking them on large stones, so small
snails are not profitable for birds and they tend to choose large species
because of their higher food value (Rosin, Olborska and Surmacki, 2011). This explains
how they came to the beach from the top of trees.
Related article:
Rosin, Olborska and Surmacki. (2011). Differences in
predatory pressure on terrestrial snails by birds and mammals. Journal of Biosciences. September 2011,
691–699.
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