Jove
Visualize
Contact Us
JoVE
x logofacebook logolinkedin logoyoutube logo
ABOUT JoVE
OverviewLeadershipBlogJoVE Help Center
AUTHORS
Publishing ProcessEditorial BoardScope & PoliciesPeer ReviewFAQSubmit
LIBRARIANS
TestimonialsSubscriptionsAccessResourcesLibrary Advisory BoardFAQ
RESEARCH
JoVE JournalMethods CollectionsJoVE Encyclopedia of ExperimentsArchive
EDUCATION
JoVE CoreJoVE BusinessJoVE Science EducationJoVE Lab ManualFaculty Resource CenterFaculty Site
Terms & Conditions of Use
Privacy Policy
Policies

Related Concept Videos

Diversity of Protists II01:27

Diversity of Protists II

2.2K
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...
2.2K
Diversity of Protists IV01:27

Diversity of Protists IV

2.1K
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...
2.1K
Muscles of the Pelvic Floor and Perineum01:26

Muscles of the Pelvic Floor and Perineum

6.4K
The muscles of the pelvic floor and perineum are crucial for supporting the pelvic organs, controlling continence, and aiding in sexual function, childbirth, and core stability. They are typically divided into the superficial perineal layer and the deep pelvic floor layer.
Perineal Layer
The perineum is a diamond-shaped area below the pelvic diaphragm, divided into an anterior urogenital triangle that contains the external genitals and a posterior anal triangle housing the anus. The urogenital...
6.4K
Phylogeny01:23

Phylogeny

64.8K
Phylogeny is concerned with the evolutionary diversification of organisms or groups of organisms. A group of organisms with a name is called a taxon (singular). Taxa (plural) can span different levels of the evolutionary hierarchy. For instance, the group containing all birds is a taxon (comprising the class Aves), and the group of all species of daisies (the genus Bellis) is a taxon. Phylogenies can likewise include just one genus (i.e., depict species relationships) or span an entire kingdom.
64.8K
Diversity of Protists III01:27

Diversity of Protists III

2.1K
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,...
2.1K
Surface Appendages of Archaea01:23

Surface Appendages of Archaea

857
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...
857

You might also read

Related Articles

Articles linked to this work by shared authors, journal, and citation graph.

Sort by
Same author

EpiCure (Epithelial Curation): a versatile and handy tool for curation of epithelial segmentation.

bioRxiv : the preprint server for biology·2026
Same author

Multifaceted conserved functions of Notch during post-embryonic neurogenesis in the annelid Platynereis.

EMBO reports·2026
Same author

Jagged-mediated lateral induction patterns Notch3 signaling within adult neural stem cell populations.

Nature communications·2026
Same author

Transcriptomic analysis of three annelid species: looking for markers of positional information.

BMC genomics·2026
Same author

FishFeats: streamlined quantification of multimodal labeling at the single-cell level in 3D tissues.

Bioinformatics (Oxford, England)·2026
Same author

A genome resource for the marine annelid Platynereis spp.

BMC genomics·2025

Related Experiment Video

Updated: Apr 14, 2026

Inducing Complete Polyp Regeneration from the Aboral Physa of the Starlet Sea Anemone Nematostella vectensis
08:17

Inducing Complete Polyp Regeneration from the Aboral Physa of the Starlet Sea Anemone Nematostella vectensis

Published on: January 14, 2017

9.2K

A metameric origin for the annelid pygidium?

Viktor V Starunov1,2, Nicolas Dray3, Elena V Belikova4

  • 1Department of Invertebrate Zoology, Saint-Petersburg State University/ Universitetskaya nab. 7/9, 199034, Saint-Petersburg, Russia. starunov@gmail.com.

BMC Evolutionary Biology
|April 17, 2015
PubMed
Summary

The annelid pygidium, or tail piece, is more complex than previously thought, featuring intricate nervous and muscular systems. This complexity challenges the notion of it being non-segmental and suggests potential homology with trunk segments.

More Related Videos

Microfocus X-ray CT microCT Imaging of Actinia equina Cnidaria, Harmothoe sp. Annelida, and Xenoturbella japonica Xenacoelomorpha
08:09

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

Published on: August 6, 2019

9.7K
Genotyping of Sea Anemone during Early Development
07:04

Genotyping of Sea Anemone during Early Development

Published on: May 13, 2019

6.2K

Related Experiment Videos

Last Updated: Apr 14, 2026

Inducing Complete Polyp Regeneration from the Aboral Physa of the Starlet Sea Anemone Nematostella vectensis
08:17

Inducing Complete Polyp Regeneration from the Aboral Physa of the Starlet Sea Anemone Nematostella vectensis

Published on: January 14, 2017

9.2K
Microfocus X-ray CT microCT Imaging of Actinia equina Cnidaria, Harmothoe sp. Annelida, and Xenoturbella japonica Xenacoelomorpha
08:09

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

Published on: August 6, 2019

9.7K
Genotyping of Sea Anemone during Early Development
07:04

Genotyping of Sea Anemone during Early Development

Published on: May 13, 2019

6.2K

Area of Science:

  • Developmental Biology
  • Evolutionary Biology
  • Zoology

Background:

  • Segmented body plans are common in animals, but the evolutionary origin of segmentation, particularly in the last common bilaterian ancestor, is debated.
  • Annelids, or segmented worms, exhibit diverse forms, with many species showing high degrees of metameric (segmented) organization.
  • The annelid pygidium (tail end) and prostomium (head end) are traditionally considered non-segmental, with the pygidium's structure and development being particularly understudied.

Purpose of the Study:

  • To investigate the detailed structure and development of the annelid pygidium.
  • To determine if the pygidium shares characteristics with the segmented trunk of annelids.
  • To explore the implications of pygidial complexity for theories on the origin of segmentation.

Main Methods:

  • Utilized advanced microscopy techniques, including various methods of microscopy.
  • Employed immunolabelling and a suite of molecular markers to analyze pygidial tissues.
  • Examined both early developmental stages and the structure of mature pygidia, including post-epitokous transformation.

Main Results:

  • The pygidium of Platynereis dumerilii possesses a complex nervous system, including a nerve ring and sensory ganglia.
  • Detailed descriptions of the pygidium's intrinsic musculature, a terminal circular blood sinus, and a unique torus-shaped coelomic cavity were provided.
  • Early developmental steps and the pygidial structure after epitokous transformation were also elucidated.

Conclusions:

  • The annelid pygidium exhibits a significantly more complex organization than previously recognized.
  • Observed pygidial characteristics bear striking resemblances to those of trunk segments, raising questions about their shared evolutionary origin.
  • The findings support re-evaluation of classical theories on segmentation, such as the cyclomeric/archicoelomate concept and the colonial theory, regarding the homology between pygidium and trunk segments.