Overview

Distribution

Range Description

Globally, this species is found from East African coast and coasts of the west Indian Ocean.

Northeastern Africa: It is found on the coasts of Somalia

Eastern Africa: This species occurs in the eastern Africa coastal strip.
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Physical Description

Diagnostic Description

Description

Habitat: Mangrove Forests. Thick, strong, elongate shells up to 3 cm, with five whorls and about 20 axial ribs. Colour grey brown. Habitat: on the trunks of mangrove trees. Distribution: W Indian Ocean. Regional names: Kis. Nyambua. (Richmond, 1997).
  • Richmond, M. (Ed.) (1997). A guide to the seashores of Eastern Africa and the Western Indian Ocean islands. Sida/Department for Research Cooperation, SAREC: Stockholm, Sweden. ISBN 91-630-4594-X. 448 pp.
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Source: World Register of Marine Species

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Ecology

Habitat

Habitat and Ecology

Habitat and Ecology
According to Brown (1994) is this species is mainly found in mangrove forests where specimens aggregate on trees and at high tide.

Systems
  • Freshwater
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Molecular Biology and Genetics

Molecular Biology

Barcode data: Cerithidea decollata

The following is a representative barcode sequence, the centroid of all available sequences for this species.


There are 2 barcode sequences available from BOLD and GenBank.

Below is a sequence of the barcode region Cytochrome oxidase subunit 1 (COI or COX1) from a member of the species.

See the BOLD taxonomy browser for more complete information about this specimen and other sequences.

ACCTTATATATTTTGTTTGGTATGTGGTCCGGTTTAGTTGGAACTGCTCTT---AGTCTCTTAATTCGAGCTGAACTGGGCCAACCCGGAGCTTTGCTTGGTGAC---GATCAACTATATAATGTAATTGTTACAGCCCATGCATTTGTTATAATTTTCTTTTTAGTAATGCCTATAATGATTGGTGGATTTGGAAACTGACTTGTTCCGCTAATA---CTCGGAGCCCCAGACATAGCCTTTCCTCGTCTAAATAATATAAGTTTCTGGTTACTTCCCCCAGCACTTTTACTTCTTCTCTCTTCTGCAGCAGTTGAAAGGGGGGTAGGAACGGGGTGAACCGTGTACCCTCCTTTGGCCGGAAACTTAGCCCATGCAGGTGGCTCTGTAGATCTG---GCCATTTTTTCCTTGCACTTAGCCGGTGTTTCTTCGATTCTAGGTGCAGTAAACTTTATTACTACAATTATCAATATACGATGACGTGGAATACAATTTGAACGTCTTCCTCTTTTTGTTTGATCAGTAAAAATTACTGCAATTCTTCTTCTTTTATCGCTTCCTGTTCTAGCGGGG---GCTATTACTATGCTTTTAACGGATCGAAATTTTAATACGGCTTTCTTTGACCCCGCAGGAGGAGGAGACCCAATTCTGTATCAACACCTC
-- end --

Download FASTA File

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Source: Barcode of Life Data Systems (BOLD)

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Statistics of barcoding coverage: Cerithidea decollata

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 2
Specimens with Barcodes: 6
Species With Barcodes: 1
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Conservation

Conservation Status

IUCN Red List Assessment


Red List Category
LC
Least Concern

Red List Criteria

Version
3.1

Year Assessed
2010

Assessor/s
Lange, C.N. & Van Damme, D.

Reviewer/s
Seddon, M., Van Damme, D., Graf, D.L., Appleton, C. & Bennett, L.

Contributor/s

Justification
This is a widespread species, reliant on mangrove habitat. It is not thought to be declining at a rate which would meet the threshold for a threatened category, and is therefore assessed as Least Concern.
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Population

Population
Usually abundant where present.

Population Trend
Decreasing
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Threats

Major Threats
The destruction of mangroves threatens this species.
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Management

Conservation Actions

Conservation Actions
No data available.
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Wikipedia

Cerithidea decollata

Cerithidea decollata, common name the truncated mangrove snail, is a species of sea snail, a marine gastropod mollusk in the family Potamididae.[1]

Description[edit]

Adults have a thick, approximately 3 cm long shell, with 5 whorls and around 20 axial ribs on each whirl. A distinguishing characteristic of adults is the broken-off tip of the shell, although this feature can be difficult to discern in some individuals.[2]

Ecology[edit]

This species is common in coastal mangrove forests, particularly near Avicennia marina trees, in western part of the Indian Ocean - Kenya, Tanzania,[3] Mozambique,[4] South Africa[4] and Madagascar.[1]

Juveniles are seldom seen and therefore little is known about their ecology. The adults feed on small organic particles (detritus) and seagrasses that are brought in with the tide.[5] Their habitat is a gently sloping intertidal zone with two high and two low tides each day. There are large differences in the duration of flooding and sea level between the two high tides each day, between seasons and between places nearer to or further from the shoreline.

Tree-climbing behaviour[edit]

When the water recedes, the snails feed scattered on the ground. Then, one or two hours before the incoming tide, they start climbing on tree trunks and gather in groups of up to several dozen specimens, waiting above the water level until the sea recedes again.[6][7] This behaviour probably makes it possible for them to avoid the unfavorable physiological effects of submersion, or possibly makes it easier to escape from marine predators such as crabs. Similar or reverse tree-climbing strategy is employed by other related species.[8]

The strategy of this particular species is unusual, because the tides are very unpredictable in this environment. The higher and lower semidiurnal tides vary in amplitude, and during neap tide, one or both high tides each day are not high enough to reach the grounds where the snails feed. The snails start climbing when the shoreline is still dozens of meters away and an hour or two before the water floods their feeding grounds. They invariably stop at a point twenty to seventy centimeters above the future water level and wait there for the tide. If the incoming high tide is too low to reach their feeding grounds, they remain on the ground until an hour before the next high tide will be high enough (especially the animals that live further inland where the shore is a bit higher and therefore more seldom flooded).[9]

It has been found out that the individuals "measure" their height by detecting the amount of energy used for climbing: when artificially loaded, the snails climbed proportionally lower, whereas they climbed higher if the tree trunk was replaced with a smoother surface or if the researchers raised the starting platform.[9] However, it is still a puzzle how the animals are able to predict the water level so far in advance. The difference in body weight caused by the fluctuation of gravity that also causes the tide is probably too low for detection by an organism this small. Chemical cues, such as hydrogen sulfide released from the ground, and acoustic cues, such as infrasound caused by the waves, are probably unreliable indicators of the water level as well, because of the local weather's influence. Every high tide is similar in amplitude to the one before the last, but the snail migration is – statistically speaking – better adjusted to the following high tide than to the one before the last.[9] The underlying process is probably regulated by an internal clock, which can be "confused" by carrying an individual to a lower or a higher part of the coastline. In this case, the animal continues to climb as it would in its original surrounding for several more days or until it gets submerged, then the mechanism "resets" and it is again able to predict the oncoming high tide reliably.[10] Since the cue used by these animals to predict the level of the incoming high tide is still a complete mystery, researchers jest that these snails can foresee the future.[9]

References[edit]

  1. ^ a b c Cerithidea decollata (Linnaeus, 1758).  Retrieved through: World Register of Marine Species on 17 May 2010.
  2. ^ Richmond, M.D. (1997). A guide to the Seashores of Eastern Africa and the Western Indian Ocean Islands. Zanzibar, Tanzania: Sida / Department for Research Cooperation, SAREC. pp. 448 pp. 
  3. ^ Machiwa, John F. & Hallberg, Rolf O. (1995). "Flora and Crabs in a Mangrove Forest Partly Distorted by Human Activities, Zanzibar". Ambio 27 (7–8). 
  4. ^ a b Branch G. M. Griffiths C. L. Branch M. L. & Beckley L. E. (2000). Two Oceans: A guide to the marine life of southern Africa. 5th impression, David Philip, Cape Town, ISBN 0-86486-250-4
  5. ^ Marguillier, S. et al. (1997). "Trophic relationships in an interlinked mangrove seagrass ecosystem as traced by d13C and d15N.". Mar. Ecol. Progr. Ser. 151: 115–121. doi:10.3354/meps151115. 
  6. ^ Vannini, Marco, Rorandelli, Rocco, Lähteenoja, Outi, Mrabu, Elisha, Fratini, Sara (2006). "Tree-climbing behaviour of Cerithidea decollata, a western Indian Ocean mangrove gastropod (Mollusca: Potamididae)". J. Mar. Biol. Ass. U.K. 86 (6): 1429–1436. doi:10.1017/S0025315406014470. 
  7. ^ Vannini, Marco, Coffa, Cecilia, Lori, Elisabeta, Fratini, Sara (2008). "Vertical migrations of the mangrove snail Cerithidea decollata (L.) (Potamididae) through a synodic month". Estuarine, Coastal and Shelf Science 78 (4): 644–648. doi:10.1016/j.ecss.2008.02.010. 
  8. ^ Harumi, O., Eiko, M., Kiyonori, T. (2002). "Tree climbing behavior of the snail Cerithidea rhizophorarum (Gastropoda: Potamididae)". Venus 61: 215–232. 
  9. ^ a b c d Vannini, Marco, Lori, Elisabetta, Coffa, Cecilia, Fratini, Sara (2008). "Cerithidea decollata: a snail that can foresee the future?". Animal Behaviour 76 (3): 983–992. doi:10.1016/j.anbehav.2008.05.016. 
  10. ^ Vannini, Marco, Mrabu, Elisha, Cannicci, Stefano, Rorandelli, Rocco, Fratini, Sara (2008). "Rhythmic vertical migration of the gastropod Cerithidea decollata in a Kenyan mangrove forest". Mar. Biol. 153 (6): 1047–1053. doi:10.1007/s00227-007-0877-8. 
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