THE VARIED ROLES OF SNAILS - National Universities Commission

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and is formed from thin sheets of calzium carbonate alternating with organic matter. This nacreous layer is secreted by cells along the entire epithelial border of the mantle. Secretion of the nacreous causes the shell to grow in thickness. This thick shell helps in protecting the soft tissues of the gastropods. The snail shells have many shapes. The fundamental shape is globose while some are conical tubes; some are spirally coiled around a central axis – the columella. The separate coils of the spiral are called the whorls. Each whorl is partially covered by its successor. The line occurring where two whorls meet is called the suture. The last whorl is called the body whorl, and it is around the opening known as the aperture. 24
Fig. 6: Shells of different freshwater snail species (After Thomas Kristensen, 2005) (f) Torsion: The Principal diagnostic criterion for the members of the class gastropoda is torsion. The 25
Page 1 and 2: THE VARIED ROLES OF SNAILS (GASTROP
Page 3 and 4: 1820 and twice that in 1930 (Martin
Page 5 and 6: contributions of snails to human ex
Page 7 and 8: a.) Production from the wild (wild
Page 9 and 10: Gastropods I: Terrestrial or Garden
Page 11 and 12: contracts and expands and this crea
Page 13 and 14: live on the surface so that they ca
Page 15 and 16: Many members of the Carrier shell f
Page 17 and 18: Most bivalves reproduce by laying m
Page 19 and 20: the snails, what is true of one spe
Page 21 and 22: principle, is a rasping tongue with
Page 23: sculptural defenses against crushin
Page 27 and 28: ight larval retractor i.e. establis
Page 29 and 30: (iii) The hypertrophy of the right
Page 31 and 32: ys two present kidneys 5. Operculum
Page 33 and 34: organs of some species and found si
Page 35 and 36: imperative for the ecosystem dynami
Page 37 and 38: oth of a direct and an indirect nat
Page 39 and 40: females.. Self fertilization is a c
Page 41 and 42: emerges and goes on a binge of repl
Page 43 and 44: of spermatozoa in males or stimulat
Page 45 and 46: d. LIFE CYCLE & LIFE BUDGET SUDIES:
Page 47 and 48: competitively loosely packed. With
Page 49 and 50: digestible vegetable. Tough plants
Page 51 and 52: Birds Various ducks Storks Kites Ot
Page 53 and 54: when mineral ions form chelate comp
Page 55 and 56: produce stress. Thus snail distribu
Page 57 and 58: Protein (g): 16 Availablecarbohydra
Page 59 and 60: or cocoyam, and palm oil or pea nut
Page 61 and 62: 1925, 1931, at Angola and Namibia;
Page 63 and 64: meat with garlic. British species a
Page 65 and 66: 4. Helicinidae 5. Fissurellidae 6.
Page 67 and 68: Helix nucuea Helix aperta Arianta a
Page 69 and 70: Archachatina calachatina marinae Ar
Page 71 and 72: sites in North Africa but are also
Page 73 and 74: infect man or animals. The five pri
Page 75 and 76:
Okafor (1989, 1990, and 1992), Ozum
Page 77 and 78:
P. aurita P. byronensis Gyraulus G.
Page 79 and 80:
one miracidium the potential of pro
Page 81 and 82:
In the snail the miracidium metamor
Page 83 and 84:
While Potadoma and Semisulcospira s
Page 85 and 86:
Clonorchiasis is caused by Clonorch
Page 87 and 88:
Table 7: Showing a list of trematod
Page 89 and 90:
promising and show reduction of pai
Page 91 and 92:
memory loss have a devastating cons
Page 93 and 94:
acteria. This bacteriostatic activi
Page 95 and 96:
The thin, quickly leached soils of
Page 97 and 98:
Snails are also pests of crops wher
Page 99 and 100:
(f) The management of the snail far
Page 101 and 102:
flakes or maize chaffs and mostly g
Page 103 and 104:
important that they are separated i
Page 105 and 106:
The profit = 1, 800,000 - 30,000 =
Page 107 and 108:
designs that are very attractive an
Page 109 and 110:
cornuarietis or of flatworms as bio
Page 111 and 112:
In few location of the world, snail
Page 113 and 114:
damages to crops. So, they must be
Page 115 and 116:
115
Page 117 and 118:
The Nigerian Field, 44 (4), 130-144
Page 119 and 120:
19. Asibey, E. O. A. and child, G.
Page 121 and 122:
32. Dei, G. J. S. (1989). Hunting a
Page 123 and 124:
J. moll. Studies, 64 (2), 173-181.
Page 125 and 126:
56. Lux moore, R. (1985). Game farm
Page 127 and 128:
69. Okafor, F. C. (1989). Consumpti
Page 129 and 130:
Proc. Symposium organized by the Br
Page 131 and 132:
Chronicle Nautilus Batavia, 104,278
Page 133 and 134:
Achatina fulicaBowdich,1822 Shell s
Page 135 and 136:
Achatina immaculata Lamarck,1822 Sh
Page 137 and 138:
Achatina stuhlmanni von Martens,189
Page 139 and 140:
Columna leai(Tryon, 1866) : São To
Page 141 and 142:
Shells of Gyraulus costulatus 141
Page 143 and 144:
Shells of Biomphalaria pfeifferi 14
Page 145 and 146:
Shells of Lanistes varicus and oper
Page 147 and 148:
147
Page 149 and 150:
Courtesy of Yurii Yashin Courtesy o
Page 151 and 152:
Yurii Yashin Yurii Yashin Yurii Yas
Page 153:
153
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THE VARIED ROLES OF SNAILS - National Universities Commission

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