title: The hatching behavior of Echinostoma trivolvis miracidia and their responses to gravity, light and chemicals.
abstract: Echinostoma trivolvis eggs developed to mature miracidia in both dark and light culture conditions as early as 7 days. Hatching initially occurred in eggs exposed to incandescent light on day 11. Those exposed to fluorescent light first hatched on day 13. Maximum hatching (50+ miracidia/day) lasted only over a 3-day span with the entire hatching period being at the most 5 days. Eggs stored in complete darkness for 21 days developed to mature miracidia in 9 days, and, when exposed to light, gave a 50+ hatch the next day. Those eggs stored for 28 and 35 days developed normally but never hatched upon exposure to light. Miracidia hatched at all times of the day without a circadian pattern. Miracidia that hatched from these trials exhibited a definite negative geotaxis in a four-tube vertical system. This response was either negated in open tubes or dominated by a positive phototaxis in the open-bottomed tubes. In horizontal chambers without the depth component, a strong positive phototaxis was also demonstrated. Miracidia showed a positive klinokinetic response, as determined in phi-chambers, to acidic compounds such as aspartic, glutamic, hydrochloric, sulfuric, and acetic acids. Snail-conditioned water prepared from Helisoma trivolvis snails also elicited a positive response. The neutral amino acid, leucine, and possible snail excretion products, Mg2+ and ammonia, did not stimulate these echinostroma miracidia.
authors.affiliation: Department of Biological Sciences, Western Illinois University, Macomb 61455.
authors.forename: P M
authors.initials: PM
authors.lastname: Nollen
mesh_terms: D000818:Animals; D002633:Chemotaxis; D006224:Cricetinae; D004449:Echinostoma / Q000502:physiology*; D006112:Gravitation; D008027:Light; D010063:Ovum / Q000502:physiology; D012908:Snails