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Related Concept Videos

The Fossil Record02:56

The Fossil Record

The fossil record documents only a small fraction of all organisms that have ever inhabited Earth. Fossilization is a rare process, and most organisms never become fossils. Moreover, the fossil record only exhibits fossils that have been discovered. Nevertheless, sedimentary rock fossils of long-lived, abundant, hard-bodied organisms dominate the fossil record. These fossils offer valuable information, such as an organism's physical form, behavior, and age. Studying the fossil record helps...
Diversity of Protists III01:27

Diversity of Protists III

Rhizaria are a diverse group of unicellular protists characterized by their threadlike cytoplasmic extensions known as pseudopodia. These structures aid in both locomotion and feeding, giving Rhizaria an amoeboid appearance. Their amoeboid morphology once led to taxonomic confusion, but molecular phylogenetics has clarified their evolutionary placement and emphasized their shared use of pseudopodia despite divergent lineages.This clade comprises diverse lineages such as Chlorarachniophyta,...
The Evidence for Evolution02:55

The Evidence for Evolution

Genetic variations accumulating within populations over generations give rise to biological evolution. Evolutionary changes can result in the formation of novel varieties and entire new species. These changes are responsible for the diverse forms of life inhabiting the planet. The evidence for evolution suggests that all living organisms descended from common ancestors.The collection of fossils within sedimentary rocks give a record of common ancestry and often depicts the history of evolution.
Surface Appendages of Archaea01:23

Surface Appendages of Archaea

Archaeal surface appendages are highly specialized structures essential for environmental adaptation, encompassing roles in adhesion, biofilm formation, and motility. Among these appendages, pili and archaella stand out for their distinct morphologies and functionalities, enabling archaea to thrive in diverse and often extreme environments.Pili: Adhesion and Biofilm FormationPili are filamentous structures assembled from pilin protein subunits, primarily contributing to adhesion and biofilm...
Diversity of Protists II01:27

Diversity of Protists II

Alveolates are a group of organisms recognized by the presence of alveoli, which are cytoplasmic sacs located beneath the cell membrane. While their function remains uncertain, alveoli may help regulate water balance by controlling how much water enters and leaves the cell. In dinoflagellates, these structures may serve as armor plates. There are three major types of alveolates: ciliates, which move using cilia; dinoflagellates, which use flagella for movement; and apicomplexans, which are...
Diversity of Protists IV01:27

Diversity of Protists IV

Amoebozoa represent a diverse group of terrestrial and aquatic protists that utilize lobe-shaped pseudopodia for locomotion and feeding. This characteristic differentiates them from the Rhizaria, which possess threadlike pseudopodia. The primary classifications within Amoebozoa include gymnamoebas, entamoebas, and the plasmodial and cellular slime molds. Phylogenetic evidence indicates that Amoebozoa diverged from a lineage that ultimately gave rise to fungi and animals.Gymnamoebas and...

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Related Experiment Video

Updated: Jul 12, 2026

Microfocus X-ray CT (microCT) Imaging of Actinia equina (Cnidaria), Harmothoe sp. (Annelida), and Xenoturbella japonica (Xenacoelomorpha)
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Microfocus X-ray CT (microCT) Imaging of Actinia equina (Cnidaria), Harmothoe sp. (Annelida), and Xenoturbella japonica (Xenacoelomorpha)

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Tentaculites: evidence for a brachiopod affinity?

K M Towe

    Science (New York, N.Y.)
    |August 18, 1978
    PubMed
    Summary

    Tentaculites shells possess a unique calcite structure, featuring ridge and groove patterns and a cross-bladed fabric. This microstructure suggests a potential evolutionary link between Tentaculites, brachiopods, and phoronids.

    Area of Science:

    • Paleontology
    • Microscopy
    • Biomineralization

    Background:

    • Tentaculites are an enigmatic group of extinct marine invertebrates.
    • Their shell microstructure and evolutionary relationships remain poorly understood.

    Purpose of the Study:

    • To investigate the shell microstructure of Tentaculites using advanced microscopy.
    • To determine potential affinities of Tentaculites with other fossil groups based on shell structure.

    Main Methods:

    • Transmission electron microscopy (TEM) was employed to examine fractured shell surfaces.
    • Detailed analysis of the calcite fabric and structural elements was performed.

    Main Results:

    • Tentaculites shells are composed of calcite.

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    Ablation of a Single Cell From Eight-cell Embryos of the Amphipod Crustacean Parhyale hawaiensis
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    Published on: March 16, 2014

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    Last Updated: Jul 12, 2026

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    08:09

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    08:02

    Dissection and Flat-mounting of the Threespine Stickleback Branchial Skeleton

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    Ablation of a Single Cell From Eight-cell Embryos of the Amphipod Crustacean Parhyale hawaiensis
    10:55

    Ablation of a Single Cell From Eight-cell Embryos of the Amphipod Crustacean Parhyale hawaiensis

    Published on: March 16, 2014

  • A distinctive ridge and groove structure was identified.
  • A cross-bladed fabric, previously observed only in articulate brachiopods, was revealed.

    • Conclusions:

    • The unique shell microstructure of Tentaculites, particularly the cross-bladed fabric, suggests a possible evolutionary relationship with articulate brachiopods.
    • Alternatively, a relationship with phoronids is also considered based on the findings.
    • Further research is needed to fully elucidate the phylogenetic position of Tentaculites.