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Questions and Answers
What does the term 'blastus' refer to in Subphylum Blastozoa?
What does the term 'blastus' refer to in Subphylum Blastozoa?
- Marine animals
- Stemmed organisms
- Buds (correct)
- Flower buds (correct)
How many classes does Subphylum Blastozoa embrace?
How many classes does Subphylum Blastozoa embrace?
6
Subphylum Blastozoa is characterized by exclusively freshwater animals.
Subphylum Blastozoa is characterized by exclusively freshwater animals.
False (B)
What type of symmetry do the animals of class Blastoidea exhibit?
What type of symmetry do the animals of class Blastoidea exhibit?
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Class Rhombifera is characterized by placed tubes or grooves that traverse thecae ______.
Class Rhombifera is characterized by placed tubes or grooves that traverse thecae ______.
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What is the significant pattern of pores in class Rhombifera?
What is the significant pattern of pores in class Rhombifera?
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Name one of the representative genera of class Rhombifera.
Name one of the representative genera of class Rhombifera.
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Study Notes
Subphylum Blastozoa Overview
- Derived from "blastus," meaning bud; resembles floral structures.
- Comprises six classes: Blastoidea, Rhombifera, Diploporita, Ecocrinoidea, Parablastoidea, and Paracrinoidea.
- Primarily characterized by the presence of a stem.
Class Blastoidea (Paleozoic Era)
- Features compact structures known as thecae and exhibits pentameral symmetry.
- Contains five ambulacra that are symmetrically arranged around the sides of the theca.
- Mouth and anus are located at the summit of the theca.
- Mostly thin-walled and only a few species are stemless.
- Lacks arms; exists solely in marine environments with regular salinity.
Class Rhombifera (Early Ordovician to Late Devonian)
- Identified by tubes or grooves that traverse through the thecae plates.
- Pores are arranged in a distinctive rhombic pattern called "pore rhombs."
- Typically possess four to five circlets.
- Two to five ambulacra are found in this class.
- Representative genera include Caryocrinites and Echinosphaerites.
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