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Uroplatus Gecko

This has nothing to do with today’s lecture but speaking of cryptic critters…. Uroplatus Gecko. We all got to eat: Foraging behaviors (cont). Spider webs: Crypsis for hunting or predator avoidance or both?. Evolution produces an array of web specializations.

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Uroplatus Gecko

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  1. This has nothing to do with today’s lecture but speaking of cryptic critters… Uroplatus Gecko

  2. We all got to eat: Foraging behaviors (cont)

  3. Spider webs: Crypsis for hunting or predator avoidance or both?

  4. Evolution produces an array of web specializations

  5. Orb weaver spiders produce an array of web specializations called stabilimentum Orb weavers use non UV reflecting silk for their orbs but UV reflecting silk for stabilimentum.

  6. Orb weaver spiders: stabilimentum and behavior

  7. Orb weaver spiders: stabilimentum and behavior

  8. Orb weaver spiders: stabilimentum and behavior

  9. Orb weaver spiders: stabilimentum and behavior

  10. Stabilimentum increase prey capture but at a cost

  11. Diversity of web specializations Nursery web spider Costa Rican net casting spiders Foraging and web-building in Dictyinidae

  12. Bolas spider: uses a pheromone-like lure to attract moths

  13. Foraging strategies: • Generalist: Species that sacrifice some profitability in exchange for less energy and time searching for prey. • Specialist: Pursue items with high profitability but must spend more time and energy searching for prey. • Different species exhibit a variety of strategies along the continuum from generalist to specialist . • The optimal foraging strategy for a species will be that which maximizes net energy intake.

  14. search for a more profitable item (type) already in diet The profitability of the "next most-profitable item type" (the ith item) Optimal foraging theory http://www.tiem.utk.edu/~gross/bioed/bealsmodules/optimal.html

  15. Foraging behavior of Glaucous-winged Gulls in rocky intertidal habitats of the Aleutian Islands. Three prey items of gulls: Muscles Chitons Urchins Three tidal zones: M (muscle) A (Alaria) L (Laminaria) Prey preference experiments, in which both search and handling times of the different prey items were zero, showed that gulls chose chitons over urchins and mussels **In nature gulls consistently selected sea urchins over chitons, but mussels were still the least preferred despite their high abundance. What would explain these preferences Irons et al. (1986)

  16. Foraging behavior of Glaucous-winged Gulls in rocky intertidal habitats of the Aleutian Islands. Discontinuity between predictions and nature are the result of a model that does not consider foraging zone preference • Energy gain when considering zones A and L only: • Urchins: 3231.3 kJ/h • Chitons: 2153.9 kJ/h

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