Arenactinia

Arenactinia
	Parnaíba Basin
Scientific classification
Kingdom:	Animalia
Phylum:	Cnidaria
Class:	Hexacorallia
Order:	Actiniaria
Genus:	Arenactinia
Species:	A. ipuensis
Binomial name
	Arenactinia ipuensis;

Last updated July 16, 2025

Arenactinia is a genus of sea anemone that lived in Brazil during the early Silurian period. Its early apperence suggest that this genus may be related to the adaptive radiation of marine ecosystems following the Late Ordovician Extinction. This genus contains one species, Arenactinia ipuensis.^[1]

It was discovered in South America in the Ipu formation in the Parnaiba Basin of Brazil.^[1]

Description

The body shapes of Arenactina can be discoidal, conical, cylindrical, flattened or bipartite. The body is divided into a cylindrical column and a exspanded base. This species processes an oral disk with discrete tentacles. This gives Arenactina a simular body shape to modern sea anemone that burrow into soft substrates.^[1]

Reference

1 2 3 Barroso, Francisco Rony Gomes; Viana, Maria Somália Sales; Agostinho, Sonia; Daly, Marymegan; Fairchild, Thomas Rich; Marques, Antonio Carlos; Pacheco, Mírian Liza Alves Forancelli (2025-03-01). "Insights into the lifestyle and preservation of Arenactinia ipuensis n. gen. et n. sp. (Anthozoa, Actiniaria) from the Early Silurian (Ipu Formation, Parnaíba Basin, Brazil)". Earth History and Biodiversity. 3: 100017. doi:10.1016/j.hisbio.2025.100017. ISSN 2950-4759.

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[Barroso-1] 1 2 3 Barroso, Francisco Rony Gomes; Viana, Maria Somália Sales; Agostinho, Sonia; Daly, Marymegan; Fairchild, Thomas Rich; Marques, Antonio Carlos; Pacheco, Mírian Liza Alves Forancelli (2025-03-01). "Insights into the lifestyle and preservation of Arenactinia ipuensis n. gen. et n. sp. (Anthozoa, Actiniaria) from the Early Silurian (Ipu Formation, Parnaíba Basin, Brazil)". Earth History and Biodiversity. 3: 100017. doi:10.1016/j.hisbio.2025.100017. ISSN 2950-4759.

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