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From Wikipedia, the free encyclopedia

Pteriomorphia
A live individual of Argopecten irradians, family Pectinidae
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Mollusca
Class: Bivalvia
Subclass: Pteriomorphia
Beurlen, 1944

The Pteriomorphia comprise a subclass of saltwater clams, marine bivalve molluscs.[1] It contains several major orders, including the Arcida, Ostreida, Pectinida, Limida, Mytilida, and Pteriida. It also contains some extinct and probably basal families, such as the Evyanidae, Colpomyidae, Bakevelliidae, Cassianellidae, and Lithiotidae.

This subclass of molluscs has lamellibranch gills, and is epibenthic. Some attach to the substrate using a byssus. The foot is reduced. The mantle margins are not fused. Gills are usually large and assist in feeding. This group includes the well known mussels, scallops, pen shells, and oysters.[2] It also includes the only members of the class bivalvia to have rudimentary eyes.

YouTube Encyclopedic

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  • 1893 World's Columbian Exposition

Transcription

Come one, come all, to the 1893 World's Columbian Exposition: the Fair that defined the future of Chicago! Industrialization! Electricity! The World's first ferris wheel! A liberty bell made out of citrus fruits! Chicago was the second largest city in the United States in 1892 and beat out some major competitors for hosting the Fair that year. The Great Chicago Fire had destroyed a large portion of the city 22 years earlier, and the American Civil War had destroyed a large portion of the entire United States 6 years prior to that, so the World's Columbian Exposition was a proverbial 'rising from the ashes', much to the pride of many Chicagoans. More than 27 million tickets were sold during the six months that the Fair was up and running on the southeast side of Chicago. That accounts for about a third of the entire US population that year, not to mention participants from 46 other countries. Admission was a steep $.50, which is about 12 bucks in today's American dollar. Some were so desperate to visit that they mortgaged their homes to travel hundreds of miles to see this spectacle of 200 temporary buildings housing 65,000 exhibits. Prizes were awarded to exceptional displays and exhibits, and one such item to win acclaim was Pabst Blue Ribbon. People continue to celebrate this victory today with ceremonies around pingpong tables in college basements around the world. Speaking of prizes, one outstanding participant from the fair was Carl Akeley, who you may certainly remember from some of our earlier episodes. In 1892 he was contracted to work on some specimens for this very exhibition. Around that time he was jonesing to move on to some bigger and better things, and it was in 1895 - two years after the fair officially closed - that he was finally hired to become The Field Museum's first chief taxidermist. In addition to fostering goodwill and happy feelings for America's industrial age and new, novel concepts of sanitation, like fair organizers designing a system to remove the 3.2 million gallons of human waste from the 3,100 toilets every day. Seriously, these are the under-appreciated accomplishments of mankind. The 1893 World's Fair is also responsible for establishing the first collections of The Field Museum. Part of the reason we didn't inherit every item from the Columbian Exposition, however, is that it was a trade show, and nearly every item was for sale. Many of the early specimens that we have from this collection still have their original price tags, including this $5 plant fossil. It's about $125 in today's money. It's a steal! Don't actually steal it. Countries from all across the globe brought trade items as bragging symbols to show off their unique natural resources. Displays devoted to economic botany boasted enticing oils, beautiful woods from native trees, gigantic bags of cannabis seeds, all for the purpose of advertising the diversity of their geographical regions, and how their natural resources contributed to the newly developing global trade network of goods. I should probably emphasize here that the Fair was probably the most significant cultural and educational event in some people's entire lives at that point; books were expensive, public schooling wasn't incredibly structured, and the world was a gigantic place without Reddit or YouTube. It was the first time many people had seen items from another country, not to mention artifacts from different continents. It's baffling to think today that something as intricate as this necklace from the Zulu of Southern Africa was, at the time, seen as 'primitive art'. The World's Fair was organized during a time in America's history when eurocentrism prevailed in the upper class, and thus was projected into most displays and exhibits. Judging by how incredibly detailed this artifact is and realizing the intense care and expertise required in creating it, I think it's safe to say that westerners in the 1890s were woefully wrong about many things. Other cringe-worthy events include organizers capitalizing on the 'novelty' of various cultural groups. They brought in Native peoples to reconstructed villages to specifically have them act out "traditional" life to fairgoers, as if their lives were spectacles to be oggled at. At that time a lot of the reason for collecting artifacts by early anthropologists was to prove by comparison the progress of the western world. Anthropology today is thankfully more about telling the human story, and not about amassing individual objects from cultures without context. Today we heavily focus on working with various cultural groups in order to co-curate collections. The fair occurred during a time when these items weren't necessarily seen as objects of study, but more as utilitarian and exotic items. Many were seen as symbols of wealth, beauty, western colonialism: everything from large trophy mounts of animals and their fashionable byproducts, to 'prizes' from colonized nations. In these objects we see reflections of schools of thought from the latter part of the 19th century. Things like meteorites weren't fully understood; one of these specimens, the Elbogen Meteorite, was originally thought to be a bad omen from the gods when it was discovered in Medieval Europe. People in the 1890s obviously didn't have the technology we have now that helps us to better understand our world, but it does makes you wonder what people 100 years from now will think of our way of seeing the world. Today we are frequently asked how we price different artifacts from the museum, what the most 'expensive' specimen is, and what criteria are used to determine insurance values. Even though specimens may come up at auction, researchers tend to value them in terms of their historical, scientific, or cultural value, rather than assigning arbitrary market values. Plus, by selling items they became prizes for individuals, and their scientific value may never be fully realized if they remain in the hands of private individuals. These new thoughts about collections and ownership were beginning to take shape at the Columbian Exposition. Other new ideas that were coming to light include notions about the conservation of our natural world. Attendees saw display after display of fancy ladies' hats that utilized feathers from exotic birds, and vast collections of precious items. Once all of these items were brought together underneath one roof, it was plain to see that limits and boundaries needed to be placed on the collection and exploration of our natural world before things went totally out of control. Even though we've had these items for 120 years, we don't know what we're going to learn about them in the future. There is no way to predict their scientific value in the years to come. Today these specimens remain on display, but only until September 7th, 2014, so make sure you come see them before then, and then they will all eventually be returned to their permanent homes within the research collections of The Field Museum to be studied for centuries to come.

Photoreceptors

Pteriomorphian bivalves possess five types of photoreceptors, each evolving independently and each associated with different clades within Pteriomorphia.[3] There are cap eyespots, pigmented cups, compound eyes, concave mirror eyes, and invaginated eyes, each having evolved independently.[3] The primary purpose of pteriomorphian eyes is to detect and respond to predators.[4] As such, pteriomorphia respond to the presence of a shadow by retracting their siphon, adduction, digging, or some combination of the three. Beyond this shadow response, however, pteriomorphia typically do not respond to other visual stimuli.[5]

Pteriomorphia have much higher rates of eye loss than eye gain and studying eye loss and gain can yield insights into the mechanisms behind convergent evolution and the evolution and regression of complex traits.[3] Eyes evolved exclusively in epifaunal lineages, and have been lost in some lineages that adopted infaunal and semi-infaunal lifestyles, suggesting a correlation between eye loss and adoption of infaunal or semi-infaunal lifestyles.[3] Additionally, eyes in Pectinidae exhibit a reduction in functionality as habitat depth increases, ending in the complete absence of eyes in deep sea species.[6]

Taxonomy

Phylogeny

The cladogram is based on molecular phylogeny using mitochondrial (12S, 16S) and nuclear (18S, 28S, and H3) gene markers by Yaron Malkowsky and Annette Klussmann-Kolb in 2012.[7]

Pteriomorphia
(c. 247 mya) Pectinidae

Palliolinae (in part)

Palliolinae (in part) and Camptonectinae

Chlamydinae

(70 mya) Pecten

Limidae (file shells)

other Pteriomorphia (oysters, mussels)

2010 Taxonomy

In 2010 a new proposed classification system for the Bivalvia was published by Bieler, Carter & Coan revising the classification of the Bivalvia, including the subclass Pteriomorphia.[8] However, the following taxonomy represents the current accepted arrangement of this subclass according to the World Register of Marine Species[9]

Subclass: Pteriomorphia

Order: Arcida[10]

(Ark shells and bittersweet shells)

Order: Ostreida[11]

(True oysters and their allies)

Order: Pectinida[12]

(Scallops and their allies)

Order: Limida[13]

(File shells and their allies)

Order: Mytilida[14]

(Saltwater mussels)

Order: Pteriida[15]

(Winged oysters and their allies)

Fossil orders

References

  1. ^ Pteriomorphia Beurlen, 1944. Retrieved through: World Register of Marine Species on 26 March 2009.
  2. ^ Barnes, Robert D. (1982). Invertebrate Zoology. Philadelphia, PA: Holt-Saunders International. p. 430. ISBN 978-0-03-056747-6.
  3. ^ a b c d Audino, Jorge Alves; Serb, Jean Marie; Rodriguez Marian, José Eduardo Amoroso (27 July 2020). "Hard to get, easy to lose: Evolution of mantle photoreceptor organs in bivalves (Bivalvia, Pteriomorphia)". Evolution. 74 (9): 2106–2120. doi:10.1111/evo.14050. PMID 32716056. S2CID 220796915.
  4. ^ Serb, Jeanne M.; Eernisse, Douglas J. (2008-10-01). "Charting Evolution's Trajectory: Using Molluscan Eye Diversity to Understand Parallel and Convergent Evolution". Evolution: Education and Outreach. 1 (4): 439–447. doi:10.1007/s12052-008-0084-1. ISSN 1936-6434. S2CID 2881223.
  5. ^ Morton, Brian (January 2001). "The Evolution of Eyes in Bivalvia". Oceanography and Marine Biology: An Annual Review: 165–205 – via ResearchGate.
  6. ^ Malkowsky, Yaron; Götze, Marie-Carolin (10 December 2013). "Impact of habitat and life trait on character evolution of pallial eyes in Pectinidae (Mollusca: Bivalvia)". Organisms Diversity and Evolution. 14 – via ResearchGate.
  7. ^ Malkowsky, Yaron; Klussmann-Kolb, Annette (May 2012). "Phylogeny and spatio-temporal distribution of European Pectinidae (Mollusca: Bivalvia)". Systematics and Biodiversity. 10 (2): 233–242. doi:10.1080/14772000.2012.676572. S2CID 84085349.
  8. ^ Bieler, R., Carter, J.G. & Coan, E.V. (2010) Classification of Bivalve families. Pp. 113-133, in: Bouchet, P. & Rocroi, J.P. (2010), Nomenclator of Bivalve Families. Malacologia 52(2): 1-184
  9. ^ Gofas, S. (2014). "Pteriomorphia". World Register of Marine Species. Retrieved 2014-08-19.
  10. ^ Arcoida Stoliczka, 1871. Retrieved through: World Register of Marine Species on 3 February 2009.
  11. ^ Ostreoida Ferussac, 1822. Retrieved through: World Register of Marine Species on 9 July 2010.
  12. ^ Pectinoida Gray, 1854. Retrieved through: World Register of Marine Species on 9 July 2010.
  13. ^ Limoida Moore, 1952. Retrieved through: World Register of Marine Species on 7 July 2010.
  14. ^ Mytiloida Ferussac, 1822. Retrieved through: World Register of Marine Species on 9 July 2010.
  15. ^ Pterioida Newell, 1965. Retrieved through: World Register of Marine Species on 9 July 2010.
This page was last edited on 26 January 2024, at 13:54
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