The Opabinia
By herp250, 14th Jul 2010 | Follow this author
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Posted in WikinutWritingEssays
This was my report on Opabinia regalis.
The Essay
The Opabinia was a small aquatic creature from the middle Cambrian era. Its full name is Opabinia regalis, and it is currently of no affinity to any major group due to its odd features that do not fit well into our classification. “Wielding a long flexible proboscis tipped with grasping spines, its reconstructed image was greeted with laughter as a pretty good joke when first presented at a scientific meeting in 1972”(Smithsonian National Museum of Natural History,
(< http://paleobiology.si.edu/burgess/opabinia.html>). It is one of the oddities found present in the Burgess Shale Formation of British Columbia, Canada. Specifically, it was found in a section known as the Phyllopod Bed, which was the most famous fossil bearing member of the Burgess Shale Formation. The animal was segmented and had an unmineralized exoskeleton (<http://bestuff.com/stuff/opabinia>). 
Its name was derived from the Opabin Pass, which is a small section between Mount Hungabee and Mount Biddle. The Opabinias’ size- as I said before was quite small, and ranged from about 4 to 7 centimeters with its main body being only approximately 5 millimeters long with 15 segments. The mouth of the Opabinia was positioned on the bottom, which is why it needed a long proboscis to be able to grab its food. This is similar in a way, to how the chilipeds and maxillae of crustaceans and the prehensile tails of monkeys are used.
“Opabinia was not an arthropod — it lacked the namesake trait of arthropods: jointed legs. However, at various times, scientists have hypothesized that it was a crustacean or a trilobite — both arthropods” (Understanding Evolution, <http://evolution.berkeley.edu/evolibrary/article/_0_2/cambrian_08>). Now, because the Opabinia has been so challenging to classify, it has found its way into groups of normal and proposed taxons. It is most best classified under the Domain: Eukarya, (unranked): Opisthokonta, Kingdom: Animalia, Subkingdom: Eumetazoa, (unranked): Bilateria & Protostomia, Super phylum: Ecdysozoa, (unranked): Panarthropoda, Phylum: Lobopodia(debating),Class: †Dinocaridida, Order: Radiodonta, Family: Opabinidae, Genus: Opabinia, Species: O. regalis.
Charles Doolittle Walcott, who was also the discoverer of the Burgess Shale Formation in 1909, discovered the Opabinia in 1912. He was born on March 31, 1850 into a poor family in Utica, New York, and died on February 9, 1927 in Washington DC. He married three times, and had two sons. Walcott was both the Secretary of the Smithsonian Institute, and an advisor to Theodore Roosevelt during his presidency. Also, Walcott joined the US Geological Survey in 1879 (after losing his previous job), and became its director in 1894.
Near 40 years ago, there was an ongoing argument about the formation of multicellular animals. The two main theories were: The Cambrian Explosion- in which multicellular organisms appeared suddenly- and then there was the theory of a gradual evolution-where species change gradually over time and leave many fossils to show each change- (these fossils were critical, in providing the evidence needed to show the stages of animals through gradual evolution. Although, our current fossil records do not support this theory.) The Opabinia was originally thought to be a strong step towards proving the Cambrian Explosion. Later, it was found that other Lobopods and the idea of stem groups (the idea of organisms existing outside of a particular crown group) suggested that evolution at the time was fast, but didn’t support any unique evolutionary process.
Walcott, the man who discovered the Opabinia, had relative misconceptions of the classification of the Opabinia. Walcott originally thought that the Opabinia was of the “Crustacea class, the Brachipoda subclass, and the Anostraca order” (Wonderful Life, Gould). To explain his misconceptions, it did have a hard shell which explained the class, (even though several missing features removed the possibility) and this rules-out the subclass and order as well.
Works Cited
<http://bestuff.com/stuff/opabinia>
Gould, Stephen Jay. Wonderful Life, W.W. Norton and Company,
1989
<http://evolution.berkeley.edu/evolibrary/article/_0_2/cambrian_08>
< http://paleobiology.si.edu/burgess/opabinia.html>
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