LIFESCI 2D03 Chapter Notes - Chapter 8: Gerridae, 91 Days, Aspidoscelis
11 Jan 2017
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8. 1 animals modify their behaviour to reduce predation risk. Cryptic colouration: morphological colouration that matches the colour of the environment to reduce detection by predators. * predator avoidance by cryptic colouration in crabs (marinquez et al. Juvenile crabs are coloured brown, tan, or white with many spots and stripes, while adults are a uniform light purple colour. Hypothesis (field): the complex colouration of juveniles is an adaptation to minimize detection by predators, because the colour of the juveniles is more cryptic on the shell- hash background. Tethered individual juvenile crabs to ceramic tiles in the ocean that were either a uniform white colour or a heterogeneous shell-hash colour. Recorded survival of all individuals over time. 30% of crabs on the white tiles survived. More than 60% of crabs on the shell-hash coloured tiles survived. Conclusion (field): juvenile crabs are indeed more cryptic when on the heterogeneous shell-hash background.
