Brief description
The purpose of this experiment was to examine the daily colour changes in relation to the tidal cycle in the fiddler crab, Uca capricornis. Experiments were conducted in the East Point Reserve, Darwin from Nov - Jan (04/05 & 05/06). Twenty-seven crabs (13 males, 14 females) were observed on the day after spring tide over several semilunar cycles. Digital photos of the crabs were taken before, during and after low tide. These photographs were examined for any changes in colour or pattern. Uca capricornis do not regularly change their colouration over the course of the day. Of the 27 individuals observed, 24 did not noticeably change their colour, and none altered their pattern.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. On the day after spring tide, over several semilunar cycles, 27 crabs were observed (13 males and 14 females), includng those within the cages and several outside. Digital photographs were taken of each crab 2 hrs - 1 hr before low tide (before), in the 1 hr around low tide (during), and 1 hr - 2hrs after low tide (after). Each crab thus had three photographs taken over a single day, each separated by 1.5 hrs.
Statement: The photographs were examined and used to identify the proportion of the crabs that were darker, brighter, or the same colour as previous photos. While this is not ideal, as it relies on human vision, using a spectrograph is not feasible as the crabs rapidly change colour when handled. As a result definitive statements cannot be made, but obvious trends can be identified.
Although 27 crabs were photographed before, during and after low tide, an additional 'big female' was photographed before and during the low-tide event, but not after. This takes the number of crabs photographed before and during low tide to 28.
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 daily colour changes associated with the fiddler crab, Uca capricornis. To examine the daily colour changes in relation to the tidal cycle.
To examine the daily colour changes associated with the fiddler crab, Uca capricornis. To examine the daily colour changes in relation to the tidal cycle.
Issued: 16 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 |
Daily Changes |
EARTH SCIENCE |
Fiddler Crab |
Ocypodidae |
Uca capricornis |
biota |
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Other Information
(Male_1_4.zip)
(Male_5_8.zip)
(Male_9_13.zip)
(Female_1_4.zip)
(Female_5_9.zip)
(Female_10_14.zip)
global : 22244700-4f90-11dc-87ba-00188b4c0af8
Identifiers
- global : 287fbb00-4b87-11dc-a1f2-00188b4c0af8
