Opposite Patterns of Diurnal Activity in the Box Jellyfish Tripedalia cystophora and Copula sivickisi

Abstract

Cubozoan medusae have a stereotypic set of 24 eyes, some of which are structurally similar to vertebrate and cephalopod eyes. Across the approximately 25 described species, this set of eyes varies surprisingly little, suggesting that they are involved in an equally stereotypic set of visual tasks. During the day Tripedalia cystophora is found at the edge of mangrove lagoons where it accumulates close to the surface in sun-lit patches between the prop roots. Copula sivickisi (formerly named Carybdea sivickisi) is associated with coral reefs and has been observed to be active at night. At least superficially, the eyes of the two species are close to identical. We studied the diurnal activity pattern of these two species both in the wild and under controlled conditions in laboratory experiments. Despite the very similar visual systems, we found that they display opposite patterns of diurnal activity. T. cystophora is active exclusively during the day, whereas C. sivickisi is actively swimming at night, when it forages and mates. At night T. cystophora is found on the muddy bottom of the mangrove lagoon. C. sivickisi spends the day attached to structures such as the underside of stones and coral skeletons. This species difference seems to have evolved to optimize foraging, since the patterns of activity follow those of the available prey items in their respective habitats.

The Jellyfish Cassiopea Exhibits a Sleep-like State

“…Although future studies are required to test whether other cnidarians sleep, field studies showing behavioral quiescence, diel vertical migration, and swimming speeds that vary with diel period [21,22,23,37] suggest that a sleep-like state may not be specific to Cassiopea . A cnidarian sleep-like state could result from either divergent or convergent evolution.…”

“…In Cnidaria, neurons are organized into a non-centralized radially symmetric nerve net [11,13,15–17] that nevertheless shares fundamental properties with the vertebrate nervous system: action potentials, synaptic transmission, neuropeptides, and neurotransmitters [15–20]. It was reported that cnidarian soft corals [21] and box jellyfish [22,23] exhibit periods of quiescence, a pre-requisite for sleep-like states, prompting us to ask if sleep is present in Cnidaria. Within Cnidaria, the upside-down jellyfish Cassiopea spp.…”

Cnidaria

“…The other, larger lens eye is oriented downwards. The eyes allow the medusae to navigate effi ciently through their mangrove habitat, to avoid predators and actively pursue prey (Garm et al 2007a(Garm et al , b , 2008(Garm et al , 2012Petie et al 2011 ).…”

Rediscovery and description of the cubomedusa <i>Alatina grandis</i> (Agassiz & Mayer, 1902) (Cnidaria: Cubozoa: Alatinidae) from Pakistani waters

“…de). But besides this, the group also presents other interesting aspects, like courtship (Lewis & Long 2005, Lewis et al 2008, Garm et al 2012, Chiaverano et al 2013, Canepa et al 2014, Carrette et al 2014, vision (Coates 2003, Nordström et al 2003, Nilsson et al 2005, Garm et al 2006, 2007a+b, 2008, Garm & Bielecki 2008 and taxonomic classification (Bigelow 1938, Werner 1973, Gershwin 2005b, 2006, Straehler-Pohl 2014, Toshino et al 2013. Also the validity of some species, especially the ones of the alatinid family, has been discussed since the beginning of the last century (Mayer 1910, Bigelow 1938, Kramp 1961, Gershwin 2005a, b, Bentlage 2010, Lewis et al 2013.…”