ArticlesPostingestive Chemosensation and Feeding by Leeches
Section snippets
Materials and methods
Leeches 2–3 g (Hirudo medicinalis, Leeches USA (Westbury Long Island, NY) and Macrobdella decora, St. Croix Biological (Stillwater, MN) were kept in artificial pond water in an incubator maintained at 19°C and starved for 3–6 months. Experiments were conducted between August 1997–December 1998 at room temperature (22–25°C) on 100–120 leeches of each species. The experimenters handled all the supplies and animals used in this study with gloves to avoid contamination with chemical stimuli from
Exchange of Feeding Solutions Experiments
In the first series of experiments, we tested whether the leeches detected any change in the chemical composition of the fluid they were ingesting. To this end, we switched the feeding solution from the control 150 mM NaCl/1 mM arginine to distilled water and scored the duration of continued ingestion following the exchange. As shown in Fig. 2A, the animals dropped off the feeding apparatus within 30 s (28 ± 5 s, mean ± SEM, n = 5) after the water reached their mouth. Removing the arginine from
Discussion
The results of this study show that the bloodsucking leeches, Hirudo medicinalis and Macrobdella decora, respond to changes in the composition of a meal during ingestion indicating that continuous “tasting” occurs during the consummatory phase. However, although the animals can detect a change, they continue to ingest some of the modified solutions that they normally would reject during the appetitive phase. For instance, leeches will probe and attach to tubes filled with NaCl alone, but they
Acknowledgements
We are grateful to Mr. Baldwin Hurns and Mr. Oscar Rodriguez (Mount Vernon High School) for their participation in some of the early experiments, and to Liz Perruccio for helpful discussion of the results. We also thank Ms. Joanne Abrahams for help with the illustrations. This work was supported by NSF Grant # IBN 9723137 to A. L. K.
References (19)
- et al.
Chemical specificity of the feeding response in Hirudo medicinalis (L.) Comp
Biochem. Physiol.
(1966) - et al.
Behavioral hierarchy in the medicinal leech, Hirudo medicinalisFeeding as a dominant behavior
Behav. Brain Res.
(1998) - et al.
Canine taste nerve responses to monosodium glutamate and disodium guanylateDifferentiation between umami and salt components with amiloride
Brain Res.
(1991) - et al.
Taste synergism between monosodium glutamate and disodium 5′-guanylate
Physiol. Behav.
(1980) Chemosensory stimuli in feeding behavior of the leech Hirudo medicinalis
J. Comp. Physiol.
(1986)Morphology of chemosensory organs required for feeding in the medicinal leech
J. Morphol.
(1987)Is chemosensory input essential for the rapid rejection of toxic foods?
J. Exp. Biol.
(1996)- et al.
Electrophysiological evidence for two transduction pathways within a bitter-sensitive taste receptor
J. Neurophysiol.
(1997) - et al.
Identification of the taste cell G-protein, alpha-gustducin, in brush cells of the rat pancreatic duct system
Histochem. Cell. Biol.
(1998)