A field guide to Kenyan mangroves
Cerithidea decollata L.
This small mangrove snail can often be seen hanging on mangrove trees at low tide at very high densities (see photos at bottom of page).
Zone: Common in the A. marina landward zone (Machiwa and Hallberg, 1995), but also present in the C. tagal / R. mucronata zone (pers. obs.).
Habitat: At outgoing tide can be found on mangrove sediments, but will climb trees before the tide returns (Cockcroft and Forbes, 1981b).
Food: Organic matter, this species is a deposit feeder (Brown 1971; Marguillier et al. 1997)
Ecological notes: Higher density in areas of higher salinity (unpublished data).
Distinguishing characteristics: Broken end of shell (but not always evident, see photo below), not pointed like T. palustris. Thick elongate shells up to 3 cm, with five whirls and about 20 axial ribs (Richmond, 1997).
Geographical range: West Indian Ocean (Richmond, 1997).
Brown DS (1971) Ecology of Gastropoda in a South African mangrove swamp. Proc malac Soc Lond 39: 263-279
Cockcroft, V.G., Forbes, A.T., 1981a. Growth, mortality, and longevity of Cerithidea decollata (Linnaeus) (Gastropoda, Prosobranchia) from Bayhead mangroves, Durban Bay, South Africa. Veliger 23(4): 300-308.
Cockcroft, V.G., Forbes, A.T., 1981b. Tidal activity rhythms in the mangrove snail Cerithidea decollata (Linn) (Gastropoda, Prosobranchia, Cerithiidae). South African Journal of Zoology. 16(1): 5-9.
Machiwa, J.F. and R.O. Hallberg, 1995. Flora and crabs in a mangrove forest partly distorted by human activities, Zanzibar. Ambio 24(7-8): 492-496.
Marguillier S, van der Velde G, Dehairs F, Hemminger MA, Rajagopal S (1997) Trophic relationships in an interlinked mangrove seagrass ecosystem as traced by d13C and d15N. Mar Ecol Progr Ser 151: 115-121
Richmond, M.D., 1997. A guide to the Seashores of Eastern Africa and the Western Indian Ocean Islands. Sida / Department for Research Cooperation, SAREC. Zanzibar, Tanzania. 448 pp.
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