Regeneration in stellate echinoderms: Crinoidea, Asteroidea, and Ophiuroidea Ben Khadra Yousra1*, Sugni Michela2,3*, Ferrario Cinzia2,3, Bonasoro Francesco2, Oliveri Paola4, Martinez Pedro5,6, Candia Carnevali Maria Daniela2 *Corresponding authors: Yousra Ben Khadra (e-mail:
[email protected]) Michela Sugni (e-mail:
[email protected]) 1: Laboratoire de Recherche, Génétique, Biodiversité et Valorisation des Bioressources, Institut Supérieur de Biotechnologie de Monastir, Université de Monastir, Monastir, Tunisia 2: Dipartimento di Scienze e Politiche Ambientali, Università degli Studi di Milano, via Celoria, 2, 20133 Milano, Italy 3: Center for Complexity & Biosystems, Dipartimento di Fisica, Università degli Studi di Milano, via Celoria, 16, 20133 Milano, Italy 4: Department of Genetics, Evolution and Environment, University College London, Darwin Building, Gower Street, WC1E 6BT London, United Kingdom 5: Departament de Genètica, Microbiologia I Estadística, Universitat de Barcelona, Av. Diagonal, 645, E-08028 Barcelona, Spain 6: ICREA (Institut Català de Recerca i Estudis Avancats), Barcelona, Spain E-mail addresses:
[email protected] (Y. Ben Khadra),
[email protected] (M. Sugni),
[email protected] (C. Ferrario),
[email protected] (P. Martinez),
[email protected] (F. Bonasoro),
[email protected] (P. Oliveri),
[email protected] (M.D. Candia Carnevali). 1 1. A phylogenetic perspective of echinoderms The phylum Echinodermata is divided in five extant classes: Crinoidea (sea lilies), Asteroidea (starfishes), Ophiuroidea (brittle stars), Holothuroidea (sea cucumbers) and Echinoidea (sea urchins). All classes are characterized by a rich fossil record (dating from the Cambrian period), which, in principle, should help to identify the relationships between the classes/species. However, this has not been the case and historically the classification of all classes has generated a heated debate.