Diel Variation in Prey Capture Behavior by the Corallimorpharian Discosoma sanctithomae: Mechanical and Chemical Activation of Feeding

Abstract

The feeding biology of corallimorpharians is poorly understood. This paper describes an envelopment method of prey capture by a Caribbean species, Discosoma (= Rhodactis) sanctithomae, and further examines the stimuli that elicit envelopment and subsequent ingestion of prey. The corallimorpharians exhibited a diel pattern of expansion and contraction of the oral disc margin and tentacles. This was correlated with the density of zooxanthellae in these tissues. The tentacles expanded during the day to expose abundant zooxanthellae. The oral disc margin contained relatively few zooxanthellae and was contracted and turned down in a convex posture during the day. At night the margin was expanded and turned up to give the oral disc a bowl-shaped posture. This allowed effective execution of the envelopment response that was successful in the capture of crustaceans, polychaetes, and small fishes that were most abundant in the plankton at night. The stimuli that elicited this predatory behavior were both mechanical and chemical. Mechanical stimulation elicited envelopment at night but was not as effective during the day. Envelopment was also activated by the imino acid proline and the tripeptide reduced glutathione at low concentrations, and four other amino acids at high concentrations. Continued contraction and ingestion responses required chemical activation. Consistent ingestion responses were caused only by reduced glutathione.

Auto- and heterotrophic responses of the coralPorites luteato large amplitude internal waves

“…At partial LAIW-temperature and full LAIW conditions, food presence did not elicit polyp expansion, apart from a few exceptions, notably among the W colonies (supplementary material Figs S4, S5). These results confirm the hypothesis that the mechanical and chemical cues triggering polyp expansion in the presence of food particles (McFarlane, 1978;Elliott and Cook, 1989) are superseded by the behavioral reaction in response to full LAIW conditions. Table 1 for seawater quality data).…”

“…The presence of food exerted a strong effect over the expansion/contraction behavior of the polyps of P. lutea, but this effect was not always positive, as opposed to previous studies (Elliott and Cook, 1989;Levy et al, 2001). In some cases, food availability caused polyps to retract rather than expand their tentacles.…”

Auto- and heterotrophic responses of the coralPorites luteato large amplitude internal waves

“…At partial LAIW-temperature and full LAIW conditions, food presence did not elicit polyp expansion, apart from a few exceptions, notably among the W colonies (supplementary material Figs S4, S5). These results confirm the hypothesis that the mechanical and chemical cues triggering polyp expansion in the presence of food particles (McFarlane, 1978;Elliott and Cook, 1989) are superseded by the behavioral reaction in response to full LAIW conditions. Table 1 for seawater quality data).…”

“…The presence of food exerted a strong effect over the expansion/contraction behavior of the polyps of P. lutea, but this effect was not always positive, as opposed to previous studies (Elliott and Cook, 1989;Levy et al, 2001). In some cases, food availability caused polyps to retract rather than expand their tentacles.…”

Algal Symbiosis in Bunodeopsis: Sea Anemones with "Auxiliary" Structures

“…Based on areal densities, Sebens and deReimer (1977) found the symbiont density in the scapus region of B. antilliensis to be 12 times higher than that in the tentacles. Similar relationships between symbiont densities and auxiliary structures were found in the tropical corallimorphs Lebrunia coralligens and L. danae, with symbiont densities three or four times higher in the pseudotentacles than in the feeding tentacles (Sebens and deReimer, 1977), and in Discosoma sanctithomae, with symbiont densities four times higher in the diskal tentacles than in the oral disk margin (Elliott and Cook, 1989).…”

Characterization of Circadian Behavior in the Starlet Sea Anemone, Nematostella vectensis

“…Although similar diel responses have been reported in other cnidarian species [5], [6], [7], [8], [9], [10], [11], [12], [13], most of these studies have not tested whether the behaviors persisted under constant conditions and thus, fail to demonstrate that the behaviors were controlled by an endogenous circadian rhythm. Recent studies report that several genes controlling circadian activities in vertebrates and Drosophila are also conserved in the cnidarian species Nematostella vectensis and Acropora millepora [25], [26], [28].…”

Auto- and heterotrophic responses of the coralPorites luteato large amplitude internal waves

“…At partial LAIW-temperature and full LAIW conditions, food presence did not elicit polyp expansion, apart from a few exceptions, notably among the W colonies (supplementary material Figs S4, S5). These results confirm the hypothesis that the mechanical and chemical cues triggering polyp expansion in the presence of food particles (McFarlane, 1978;Elliott and Cook, 1989) are superseded by the behavioral reaction in response to full LAIW conditions. Table 1 for seawater quality data).…”

“…The presence of food exerted a strong effect over the expansion/contraction behavior of the polyps of P. lutea, but this effect was not always positive, as opposed to previous studies (Elliott and Cook, 1989;Levy et al, 2001). In some cases, food availability caused polyps to retract rather than expand their tentacles.…”

Algal Symbiosis in Bunodeopsis: Sea Anemones with "Auxiliary" Structures

“…Based on areal densities, Sebens and deReimer (1977) found the symbiont density in the scapus region of B. antilliensis to be 12 times higher than that in the tentacles. Similar relationships between symbiont densities and auxiliary structures were found in the tropical corallimorphs Lebrunia coralligens and L. danae, with symbiont densities three or four times higher in the pseudotentacles than in the feeding tentacles (Sebens and deReimer, 1977), and in Discosoma sanctithomae, with symbiont densities four times higher in the diskal tentacles than in the oral disk margin (Elliott and Cook, 1989).…”

Characterization of Circadian Behavior in the Starlet Sea Anemone, Nematostella vectensis

“…Although similar diel responses have been reported in other cnidarian species [5], [6], [7], [8], [9], [10], [11], [12], [13], most of these studies have not tested whether the behaviors persisted under constant conditions and thus, fail to demonstrate that the behaviors were controlled by an endogenous circadian rhythm. Recent studies report that several genes controlling circadian activities in vertebrates and Drosophila are also conserved in the cnidarian species Nematostella vectensis and Acropora millepora [25], [26], [28].…”

Auto- and heterotrophic responses of the coralPorites luteato large amplitude internal waves

“…At partial LAIW-temperature and full LAIW conditions, food presence did not elicit polyp expansion, apart from a few exceptions, notably among the W colonies (supplementary material Figs S4, S5). These results confirm the hypothesis that the mechanical and chemical cues triggering polyp expansion in the presence of food particles (McFarlane, 1978;Elliott and Cook, 1989) are superseded by the behavioral reaction in response to full LAIW conditions. Table 1 for seawater quality data).…”

“…The presence of food exerted a strong effect over the expansion/contraction behavior of the polyps of P. lutea, but this effect was not always positive, as opposed to previous studies (Elliott and Cook, 1989;Levy et al, 2001). In some cases, food availability caused polyps to retract rather than expand their tentacles.…”

Algal Symbiosis in Bunodeopsis: Sea Anemones with "Auxiliary" Structures

“…Based on areal densities, Sebens and deReimer (1977) found the symbiont density in the scapus region of B. antilliensis to be 12 times higher than that in the tentacles. Similar relationships between symbiont densities and auxiliary structures were found in the tropical corallimorphs Lebrunia coralligens and L. danae, with symbiont densities three or four times higher in the pseudotentacles than in the feeding tentacles (Sebens and deReimer, 1977), and in Discosoma sanctithomae, with symbiont densities four times higher in the diskal tentacles than in the oral disk margin (Elliott and Cook, 1989).…”

Characterization of Circadian Behavior in the Starlet Sea Anemone, Nematostella vectensis

“…Although similar diel responses have been reported in other cnidarian species [5], [6], [7], [8], [9], [10], [11], [12], [13], most of these studies have not tested whether the behaviors persisted under constant conditions and thus, fail to demonstrate that the behaviors were controlled by an endogenous circadian rhythm. Recent studies report that several genes controlling circadian activities in vertebrates and Drosophila are also conserved in the cnidarian species Nematostella vectensis and Acropora millepora [25], [26], [28].…”