HUNGER OVERCOMES FEAR IN NASSARIUS FESTIVUS, A SCAVENGING GASTROPOD ON HONG KONG SHORES

Field observations of the alarm response to crushed conspecifics in the freshwater snail Pomacea canaliculata: effects of habitat, vegetation, and body size

“…Since snails frequently fed on weeds and algae in the study sites, this suggests that the intensity of the alarm response is related to the hunger level of snails. A similar trade-off between hunger and alarm responses (''hunger overcomes fear''; Morton et al 1995) has been reported in marine snails such as Nassarius siquijorensis, N. festivus, and Acanthina monodon (Morton et al 1995;Morton and Chan 1999;Soto et al 2005).…”

“…Aquatic snails also show alarm responses, including burying themselves in the soil (Snyder and Snyder 1971;Atema and Stenzler 1977), crawling out of the water (Alexander and Covich 1991a, b;Covich et al 1994;Lewis 2001), increased use of sheltered places (Turner 1996), and moving to the surface of the water (Dewitt et al 1999). Although there have been several field studies on alarm responses in marine snails (Morton et al 1995;Morton and Chan 1999;Soto et al 2005), information on the responses of freshwater snails in the field is scarce and confined to the order Pulmonata (Alexander and Covich 1991a;Turner 1996). Very little is known on the alarm responses of freshwater snails of the superorder Caenogastropoda in the field.…”

Functional and ecological aspects of the mucus trails of the intertidal prosobranch gastropod Littorina littorea

“…Unless there is intense competition for benthic food resources, it is unlikely that L. littorea would experience starvation for greater than ~10 d and so is unlikely to change foraging behaviour when isolated from conspecifics. Morton et al (1995) described how when the snail Nassarius festivus was starved (for a period >14 d), the organism changed strategy, overcoming 'fear' of predation. After a 5 wk period of starvation, pedal mucus production in the Antarctic limpet Nacella concinna dropped to 61% of the original (satiated) levels (Peck et al 1993).…”

“…The food of L. littorea comprises macroalgae and microalgae, and the strong seasonal cycles in food abundance (Castenholz 1961, Hill & Hawkins 1991 makes starvation a distinct possibility for L. littorea. Starvation has been shown to prompt a change in foraging strategy in other marine gastropods (Morton et al 1995, Morton & Chan 1999. In L. littorea, preliminary experiments by Newell (1958) showed that starved snails, once they had encountered and eaten food, made longer feeding excursions below water.…”

Trophic transfer of trace metals: subcellular compartmentalization in bivalve prey, assimilation by a gastropod predator and in vitro digestion simulations

“…The neogastropods Nassarius festivus were collected by hand from the intertidal sandflat at Hoi Sing Wan in Tolo Harbour, Hong Kong. During low tide, freshly broken open specimens of the clams Ruditapes philippinarum were placed in shallow (<1 cm) pools; N. festivus were attracted chemically to the clams after they had been stimulated to emerge from being burrowed in the sand (Morton 1990, Morton et al 1995.…”