Brief description
The purpose of the experiment was to examine the colour changes associated with the semilunar cycle in the fiddler crab, Uca capricornis. Experiments were conducted in the East Point Reserve, Darwin from Nov - Jan (04/05 & 05/06). 1m diameter cages were constructed and stocked with 4 crabs of the species Uca capricornis. During one semilunar cycle, from one neap tide to the next, digital photographs were taken of 22 crabs (10 males, 12 females) active in the cages at approximately low tide. Photos were examined to observe any colour changes on a day to day basis. The results show that Uca capricornis do not rythmically change their colour or pattern between moults. Although some individuals did exhibit a slight variation, by brightening or darkening existing colours, there was no apparent trend in the number of crabs either brightening or darkening with respect to the time in the cycle.Lineage
Statement: 5 circular cages were constructed (1m in diameter) out of flyscreen mesh and buried 10cm in the mud within the Uca capricornis population. The cages protruded a further 20cm above the mud and a laminate strip glued around the inner and outer top 5cm prevented crabs from climbing in or out of the cage. All existing crabs were removed from the cages and restocked with 4 crabs; a small male and female and a large male and female. A digital photograph of their carapace was taken. During one semilunar cycle, from one neap tide to the next, digital photographs of 22 crabs (10 males and 12 females) active in the cages at approximately low tide were taken.
Statement: Over the duration of the experiment several of the crabs disappeared and had to be replaced. A couple of these reappeared, but were distinguishable by their size and colour pattern.
The photographs were examined and used to identify the proportion of the crabs that were darker, brighter, or the same colour as the previous day to determine whether they underwent any rythmic colour changes. While this is not ideal, as it relies on human vision, using a spectrograph for long-term sequential measurements is not feasible as the crabs rapidly change colour when handled. Because observations were only made over a single cycle, definitive statements cannot be made. Obvious trends however can be identified.
Notes
CreditAustralian Research Council (ARC) Centre for Excellence for Vision Science
Credit
Australian Research Council (ARC) Discovery Grant
Australian Research Council (ARC) Discovery Grant
Credit
The Centre of Visual Sciences (CVS, The Australian National University)
The Centre of Visual Sciences (CVS, The Australian National University)
Credit
The Australian National University PhD Scholarship
The Australian National University PhD Scholarship
Purpose
To examine the colour changes associated with the semilunar cycle in the fiddler crab, Uca capricornis
To examine the colour changes associated with the semilunar cycle in the fiddler crab, Uca capricornis
Issued: 15 08 2007
Data time period: 2004-11 to 2005-01
Data time period: 2005-11 to 2006-01
text: westlimit=130.5; southlimit=-13; eastlimit=131; northlimit=-12
text: uplimit=0; downlimit=0
Subjects
28 960036 |
ANIMALS/INVERTEBRATES |
ARTHROPODS |
BIOLOGICAL CLASSIFICATION |
Behavioural Ecology |
Crustaceans |
Colour Pattern |
EARTH SCIENCE |
Fiddler Crab |
Ocypodidae |
Semilunar Cycle |
Uca capricornis |
biota |
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Other Information
(Male1_2Crabs.zip)
(Male3_4 Crabs.zip)
(Male5_6Crabs.zip)
(Male7_8Crabs.zip)
(Male9_10Crabs.zip)
(Female1_2Crabs.zip)
(Female3_4Crabs.zip)
(Female5_6Crabs.zip)
(Female7_8Crabs.zip)
(Female9_10Crabs.zip)
(Female11_12Crabs.zip)
global : 22244700-4f90-11dc-87ba-00188b4c0af8
Identifiers
- global : 916df390-4af4-11dc-a790-00188b4c0af8
