Questions and Answers
How are brachiopods traditionally classified?
The traditional classification of Brachiopods is still used today.
False
List the levels in the Linnean classification system.
Kingdom, Phylum, Class, Order, Family, Genus, Species
What are phylogenetic differences?
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What are the two classes in the traditional classification system of Brachiopods?
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When did the Class Articulata and Class Inarticulata exist?
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What makes a good guide fossil?
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What are bilaterians?
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What are radiata?
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How are Brachiopods currently classified?
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When did the Orthida exist?
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When did the Pentamerida exist?
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When did the Order Productida exist?
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When did the Order Rhynchonellida exist?
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When did the Order Spiriferida exist?
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When did the Order Strophomenida exist?
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When did the Order Terebratulida exist?
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What shell geometry do brachiopods exhibit?
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How do you tell the difference between bivalves and brachiopods?
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What are the main components of a brachiopod's shell?
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What are brachiopod shells made of? Why is this significant?
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What does the commissure represent on a brachiopod's shell?
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Which is the dorsal surface on a brachiopod?
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Which is the ventral surface on a brachiopod?
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What is the unique purpose of muscles in a brachiopod?
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What is the purpose of sulcus?
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What is the purpose of the pedicle?
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What is the purpose of the ribs on a brachiopod's shell?
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What are two reasons why a brachiopod might have a thick shell?
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Study Notes
Classification of Brachiopods
- Brachiopods belong to the Phylum Brachiopoda, traditionally divided into two classes:
- Class Inarticulata (including Order Lingulida)
- Class Articulata (including various orders such as Orthida, Pentamerida, Productida, Rhynchonellida, Spiriferida, Strophomenida, and Terebratulida).
- Traditional classifications are now considered outdated due to lack of phylogenetic distinctions between Articulata and Inarticulata.
Linnean Classification System
- The hierarchy consists of levels: Kingdom, Phylum, Class, Order, Family, Genus, and Species.
Guide Fossils
- Effective guide fossils are free-moving, widespread, rapidly evolving, abundant, readily preserved, cross-environmental, and easily recognizable.
- The most critical features are rapid evolution and preservation.
Types of Animals
- Bilaterians exhibit bilateral symmetry, while Radiata includes radially symmetrical animals like jellyfish.
Current Classification of Brachiopods
- Presently, brachiopods are classified into three sub-phylums:
- Linguliforms
- Craniforms
- Rhynconelliforms
Historical Context of Orders
- Orthida existed from Cambrian to Permian.
- Pentamerida existed from Cambrian to Devonian.
- Order Productida spanned Ordovician to Permian.
- Order Rhynchonellida has existed from Ordovician to Recent.
- Order Spiriferida was present from Ordovician to Triassic.
- Order Strophomenida extended from Ordovician to Carboniferous.
- Order Terebratulida persisted from Devonian to Recent.
Shell Characteristics
- Brachiopods have inequivalve but equilateral shells, demonstrating bilateral symmetry, where each valve differs.
- Distinct from bivalves, brachiopods have valves that are symmetrical individually but not when compared to each other.
Shell Composition
- Brachiopod shells primarily consist of low magnesian calcite, making them strong and resistant to erosion, which aids in preservation.
- The shell includes components like dorsal and ventral surfaces, a hole for pedicle, ribs, beak, and commissure (representing growth lines).
Functional Anatomy
- The dorsal surface is defined as the side lacking the pedicle attachment.
- The ventral surface features the pedicle attachment.
- Two sets of muscles are present: one for opening the shell and one for closing it.
- The sulcus assists in filter feeding by channeling water during the feeding process.
- The pedicle secures the brachiopod to the substrate, preventing displacement by current.
- Ribs enhance shell strength, while thicker shells provide stability, help prevent flipping, and serve as defense against predators.
Brachiopod Shell Structure
- Three types of brachiopod shell structures exist, although details are needed for completion.
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Description
Test your knowledge on the classification of brachiopods with this flashcard quiz. Discover their historical classifications and the reasons why traditional methods are being reconsidered. Perfect for biology enthusiasts and students!