Development and population growth of Hydra viridissima Pallas, 1766 (Cnidaria, Hydrozoa) in the laboratory

Abstract

Hydras, the most representative freshwater Cnidaria, are of common occurrence in bodies of water in every continent except Antarctica. This study was planned with the aim of maintaining a population of Hydra viridissima in laboratory culture to enable the determination of the individual and population growth-rates of this species, as well as its population doubling time and generation time, with a view to employing these common animals as test-organisms in ecotoxicological assays. The organisms were maintained in reconstituted water at 20 ± 2 °C, illuminated at 800 lux with a photoperiod of 12 hours light: 12 hours dark, and were fed on neonates of the cladoceran Ceriodaphnia silvestrii (3 or 4 neonates per hydra, 3 times a week). The individual growth-rate (k) of the species was 0.43, the maximum length of the column 2.53 mm and the generation time 6.6 ± 1.5 days on average. The hydra population showed an intrinsic growth-rate (r) of 0.0468, according to the fitted curve, and a doubling time of 14.8 ± 2.63 days. Hydra viridissima is easy to grow in the laboratory and performs well in the conditions used in this study. It is thus a promising candidate test-organism for ecotoxicological studies.Keywords: freshwater Cnidaria, individual growth, population growth, culture of hydras, Hydra viridissima. Desenvolvimento e crescimento populacional de Hydra viridissimaPallas, 1766 (Cnidaria, Hydrozoa) em laboratório ResumoAs hidras, os mais representativos Cnidaria de água doce, são organismos comuns em corpos de água doce de todos os continentes, exceto na Antártida. O objetivo do presente estudo foi manter o cultivo em laboratório da espécie Hydra viridissima, determinando-se o crescimento individual e populacional desta espécie, assim como seu tempo de duplicação da população e de geração, visando sua utilização como organismo-teste em ensaios ecotoxicológicos. Os organismos foram mantidos em água reconstituída, a uma temperatura de 20 ± 2 °C, com luminosidade de 800 lux e fotoperíodo de 12 horas luz/ 12 horas escuro, e foram alimentados com neonatas do Cladocera Ceriodaphnia silvestrii (3 a 4 neonatas por indivíduo). A taxa de crescimento individual (k) obtida foi de 0,43, o comprimento máximo da coluna das hidras foi de 2,53 mm e o tempo de geração foi, em média, de 6,6 ± 1,5 dias. A espécie apresentou uma taxa intrínseca de crescimento populacional (r) igual a 0,0468 para a curva ajustada e um tempo de duplicação da população de 14,8 ± 2,63 dias. A espécie Hydra viridissima é de fácil cultivo em laboratório e apresentou um bom desempenho nas condições testadas, sendo, portanto, um potencial organismo-teste para estudos ecotoxicológicos.Palavras-chave: Cnidaria de água doce, crescimento individual, crescimento populacional, cultivo de hidras, Hydra viridissima.

Interference of asexual and sexual reproduction in the green hydra

“…Then, mature H. viridissima and subsamples of asexual individuals were photographed and measured with MultiScanBase v. 13.01 software. Because polyps can shrink and individuals differ in length, the size of each animal was not measured by column length, the metric used previously (Forrest 1959;Massaro and Rocha 2008), but by surface area (A H ). H. viridissima surface area was calculated from the equation of the lateral cylinder surface area:…”

Fast Cycling Culture of the Marine AnnelidPlatynereis dumerilii

“…Reproductive characteristics of animal laboratory models used for transgenesis/genome editing experiments. References: (a) (Butt et al, 1992), (b) (Akazawa et al, 2021), (c) (Dominguez & Edwards, 2010), (d) (Shankland et al, 1992), (e) (Iyer et al, 2019), (f) (Williams & Jékely, 2016), (g) (A. H. L. Fischer et al, 2010), (h) (Seaver, 2016), (i) (Ebert, 2005), (j) (Yamaguchi & Yoshida, 2018), (k) (Schröder et al, 2008), (l) (Howe, 1962), (m) (Lawrence et al, 2012), (n) (Wittbrodt et al, 2002), (o) (Jeffery, 2020), (p) (Blackburn & Miller, 2019), (q) (Beck & Slack, 2001), (r) (Wolf & Hedrick, 1971), (s) (Tilley et al, 2022), (t) (Phifer-Rixey & Nachman, 2015), (u) (Weber & Olsson, 2008), (v) (Darling et al, 2005), (w) (Kaliszewicz, 2011), (x) (Massaro & Rocha, 2008), (y) (Frank et al, 2001), (z) (Lechable et al, 2020), (aa) (Iglesias et al, 2004), (bb) (Meneely et al, 2019) Table 2 provides an overview of current metazoan models that have been acclimated in laboratory settings for experiments involving genetics and reverse genetics. This list includes a mix of models that have been developed for a long time, some for more than a century, with well-established protocols and numerous publications utilizing these techniques (such as the house mouse, fruit fly, and Caenorhabditis elegans), as well as several other models where efforts to develop genetic approaches are still in their early stages.…”

Observaciones ecológicas, corológicas y taxonómicas de hídridos dulceacuícolas (Cnidaria, Hydrozoa: Hydridae) en la Cuenca del Duero

“…Distintos taxones del género Hydra Linnaeus, 1758 (Cnidaria; Hydrozoa) han sido ampliamente utilizados tanto para bioensayos de toxicidad, como en estudios de genética, histología y fisiología animal para comprender los procesos de regeneración de tejidos e incluso partes enteras de su cuerpo con simetría radial (Bode, 2003;Khalturin et al, 2008), hasta la total senescencia (Martínez & Bridge, 2012). Sus rápidos ciclos de reproducción en cautividad (asexuales por gemación), su elevada y rápida tasa de regeneración, su plasticidad fenotípica y su facilidad de mantenimiento en laboratorio (Massaro & Rocha 2008) han favorecido su popularización en este tipo de trabajos científicos.…”