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Hippopodius hippopus (Forsk��l, 1776) Distribution in South America: Pacific Ocean, Colombia, from 7��N to 1��N (Alvari��o 1976; Cely & Chiquillo 1993), Peru, from 8o S to 16o S (IMARPE database), Chile, at 23��S off Antofagasta (Pag��s et al. 2001; Apablaza & Palma 2006); Atlantic Ocean, off French Guiana (Leloup 1934; Leloup & Hentschel 1935), Brazil to Argentina, from 0�� to 48��S (Moser 1925; Seguin 1965; Alvari��o 1968, 1971; Nogueira & Oliveira 1991; Dias 1994; Pugh 1999; Migotto et al. 2002; Araujo 2006, 2012; Araujo et al. 2010; Silveira & Morandini 2011; Bonecker et al. 2014). Habitat: neritic and oceanic species, epipelagic, widely distributed in tropical, subtropical and temperate waters (Alvari��o 1971; Pugh 1974; Pag��s & Gili 1992; Pugh & Gasca 2009; Araujo 2012; Bonecker et al. 2014)., Published as part of M. P. Oliveira 1,16, S P. Miranda 2, *,, Es W. Mianzan 10,, Ro E. Migotto 11,, Ne B. Nascimento 2,11, Eli Nogueira J��nior 12,, Er Qui��ones 13,, Izio Scarabino 14,, T��n Schiariti 10,, Io N. Stampar 15,, Tronolone 2, , Qu��ria B. & Onio C. Marques 2,11, 2016, Census of Cnidaria (Medusozoa) and Ctenophora from South American marine waters, pp. 1-256 in Zootaxa 4194 (1) on page 189, DOI: 10.11646/zootaxa.4194.1.1 more...

Some planktonic coelenterates respond to potentially harmful stimulation by protective involution, others by escape behaviour. Examples of protective involution are seen in the ‘crumpling’ behaviour of various hydrome‐dusae (Sarsia, Euphysa) and of siphonophores such as Hippopodius. Involution may be accompanied by striking visual displays e.g. light emission in Euphysa, light emission and blanching in Hippopodius. These displays probably serve to startle or blind interlopers. In Hippopodius, light emission in the dark would have the same effect as blanching in the light, an example of behavioural self‐mimicry. Animals employing escape locomotion include the ctenophore Euplokamis, the siphonophore Nanomia and the rhopalonematid medusa Aglantha. All of these forms have evolved giant axons that facilitate escape by reducing response time. The central nervous circuitry underlying locomotion in Aglantha is reviewed. In a few cases (e.g. Aglantha and possibly Nanomia), the responses described can be seen as de... more...

The jellyfish Euphysa emits light when touched, stimulated electrically or shaken in the water. Light is emitted over the whole subumbrellar surface. The source of light is the subumbrellar endodermal epithelium. The response accompanies muscular involution (‘crumpling’) and is spread by all-or-none action potentials propagated in the epithelium itself. Light emission is calcium dependent, but propagation of the triggering events is not. Octanol blocks propagation but light is still emitted in the immediate vicinity of the stimulating electrode. Light emission consists of discrete flashes which sum and facilitate with repeated stimulation. Although the triggering impulses propagate over the entire epithelium, the threshold for light emission varies regionally. The response more closely resembles that described for thesiphonophore Hippopodius than those of leptomedusae such as Aequorea. Light emission is best viewed as a startle response. more...

1. Four responses are spread by through-conducting excitable epithelia in the nectophores: luminescence, blanching, muscular involution, and secretion. Swimming, which is independently controlled by the nervous system, is inhibited by epithelial impulses.2. Luminescent flashes are correlated one for one with epithelial impulses. At least three impulses must be propagated before the first flash is recorded. Flashes sum and facilitate. Pacemaker-like after-discharges may continue after stimulation has ceased. Not all regions of the epithelium luminesce equally, and the active area can shift during a single luminescent episode, although the excitatory impulses pass across all regions equally. No steady luminescent glow has been observed. Comparisons are drawn with other luminescent systems.3. Luminescence is generated intracellularly within the exumbrellar epithelium, but blanching (opacity) is associated with formation of granules in the adjacent mesogloea. The response builds up to saturation level within ... more...