On
February 19, 2015 I visited Pinnacle Gulch tide pools at near Bodega Bay, CA.
While at Pinnacle Gulch our Marine Ecology class, Biology 335, investigated the
intertidal zone by placing four transect lines and then examining the organisms
and substrates along them using different sized quadrants and methods. During
the first hour we spent our time observing the high intertidal zone while the
tide receded. I found no starfish even when starting to venture into the deeper
water so when my professor, Dr. Shannon Lee, told one group to look specifically for
starfish around the transect line I figured this would be a pointless task.
However to my great surprise when we reached low tide, there a large of
starfish that revealed themselves in the low intertidal zones. This was
surprising because I didn’t expect it, but what really stunned me was the
starfish on on large rock that were clear-blue and only a few centimeters at most.
Once I got back to my house after
class and showed my fiancé these adorable creatures I decided to do some
research on them to find out if they were baby starfish or just a smaller
starfish species. I have determined this starfish in the beginning stages of
its adult stage where it has transformed from larvae and settled in the
intertidal zone. The two types of starfish that I observed while at the tide
pools were Pisaster ochraceus (ochre star) and Patiria miniata (bat star) but even after extensive
research I am not completely sure what type this young starfish is.
My best educated guess, after doing
a great deal of research, is that this small starfish is a small bat. I could
be completely wrong but I will explain my reasoning. The biggest reason I
believe this is a bat star is because of the two starfishes reproduction
cycles. The ochre sea star tends to reproduce in the springtime but the bat is known
for reproducing all year. This yearlong reproduction is why Patiria miniata is a very useful
organism for marine study, but they have two main reproducing times: summer and winter (wallawalla.edu). These two starfish both reproduce through sexual production in which the female and male both secret there gametes into the water and create a fertilized egg. This fertilized egg quickly becomes a microorganism that floats in the water and does not return to the tide-pools to attach to the rocks for a few months (30-60 days). Therefore is the Patiria miniata were to reproduce in the winter, a young starfish may be found in February or March which is the time period I discovered the young starfish in question. The young starfish that I examined
also had light colored markings on the arms that are very similar to that of an adult bat star. This linear pattern is much closer that of the bat star than the sporadic lines of the ochre star. Both the sea stars that were at Pinnacle Gulch have very similar life cycles and live in the same
low-intertidal zone, so without studying the starfish for longer periods and
being able to visibly watch the life cycles of both, I am left to using online
resources to try and determine a species at such a young age.
Another thing that I noticed was that the starfish were much lower where the majority of the mussel beds were. This is due to the keystone predator concept, in which the starfish prey on the mussels and therefore control their growth. The concept, specifically with starfish and mussels, was discovered by the zoologist Robert Paine (britannica.com). The mussels that grow the lowest will be eaten by the starfish so this is why, by visual observation, it appears the two exist solely in different areas of the tide pool. If our class was to remove the starfish from Pinnacle Gulch, the mussels would then take over more of the area as long as they were able to withstand the conditions of the lower intertidal.
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