Balanoglossus

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Balanoglossus
Balanoglosse - 2.jpg
Unidentified specimen from Réunion
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Hemichordata
Class: Enteropneusta
Order: Enteropneusta
Family: Ptychoderidae
Genus: Balanoglossus
Delle Chiaje, 1829
Species

See text.

Balanoglossus is a genus of ocean-dwelling acorn worms. It has zoological importance because, being hemichordates, they are an "evolutionary link" between invertebrates and vertebrates. Balanoglossus specimens are deuterostomes, and resemble the chordates in that they possess branchial openings. [1]

Contents

Their heads are between 2.5 mm (1/10 in) and 5 mm (1/5 in) wide.

Discovery

Johann Friedrich von Eschscholtz discovered Balanoglossus in 1825 on Mashail Island, and described it as a worm-like holothurian. The discovery of gill slits in these animals by Alexander Kovalevsky (1865) led to the creation of the class Enteropneusta by Carl Gegenbaur (1870).

Classification

William Bateson (1885) originally included them in phylum Chordata. [2] Hyman (1959), however, placed them near Echinodermata and gave Hemichordata a status of an independent phylum.

Habitat

Acorn worms. Specimens 10 and 11 are Balanoglossus. Enteropneusta.png
Acorn worms. Specimens 10 and 11 are Balanoglossus.

Balanoglossus are burrowing, exclusively marine animals. They are found in shallow waters between tide marks along the coast of warm and temperate oceans.

Species

The World Register of Marine Species lists the following species: [3]

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References

  1. Morgan, Thomas (January 1894). The development of balanoglossus. T. H. Morgan.
  2. Bateson, William (January 1, 1885). "II. Note on the later stages in the development of Balanoglossus Kowalevskii (Agassiz), and on the affinities of the enteropneusta". Proceedings of the Royal Society of London. 38 (235–238): 23–30. doi:10.1098/rspl.1884.0058.
  3. Balanoglossus - delle Chiaje, 1829 World Register of Marine Species. Retrieved 2022-12-14.