Life History & Behaviour

C. parthenopeum are gonochoristic animals in the sense that each individual are of a single sex. They have a short breeding period that occurs only at certain times of the year. In the study done by Laxton, 1969, it was observed that pairing of C. parthenopeum individuals began in October but copulation only occurred just before egg-laying in January of the following year, carrying on into March with some extending until May. Copulation was also found to be brief, hardly lasting more than a day. Eggs laid are cared for by the female for a month until they hatch. The C. parthenopeum veliger larvae that emerges from the eggs has a remarkable feature shared by all ranellids in which they are long-lived and teleplanic, with larval life recorded to be up to a year in these animals including C. pileare and C. nicobarium (Scheltema, 1971). It have been observed that the larvae undergo growth stasis by shifting to an equilibrial condition of no growth in the absence of environmental cues and inhibit metamorphosis even after it has become competent (Pechenik, 1984). Poorly calcified larval shells (protoconch) enables it to achieve long distance travel and the shell is later strengthened by tanning their shell proteins (Pechenik, 1984). Reproduction of the closely related C. pileare occurs through aggregations of 2 or more males to a female. The females lay their heavily yolked eggs in masses within an egg capsule at intermittent intervals (Laxton, 1969). Experiments done by Muthiah & Sampath, 2000, estimated that C. pileare produced an average of 200 egg capsules with 2985 eggs each.

Feeding

Ranellidae are grouped together with other predatory gastropods as a predatory grazer and feeds on mostly bivalves and ascidians, with other types being predators and scavengers (Laxton, 1971). They hunt with the use of their well developed eyes, chemoreception through the use of their osphradium and also by their cephalic tentacles. This was shown by Laxton, 1971, where grazing cymatiids only responded to prey items placed in their vicinity when there was a current flowing. Even when there was no prey placed with them, the animals only moved when there was water movement and most of this movements were upstream to allow water to flow into their osphradium (Laxton, 1971).

Prey intrusion of ascidians are achieved by grasping the prey with its foot and plunging its proboscis into the prey through a temporary groove in the foot. Once the proboscis have made contact with the test, the radula is thrusted out by the odontophore with the teeth erected into a rasping position. The jaws then bite down at the fullest extent of the radula to either cut flesh or hold the prey as the radula is retracted (Laxton, 1971). The predation on bivalves by C. parthenopeum are not well known, but the closely related C. pileare uses an anaesthetising fluid on unwary bivalves so as to prevent them from closing its shell (Houbrick & Fretter, 1969). These salivary fluids have been found in other gastropods families such as ranellidae, cassidae and tonnidea (Houbrick & Fretter, 1969).