NPB 102 Lecture 21: Lecture 21
1 Jun 2018
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Lecture 21
Is behavior adaptive?
- Regarding choice of whelks by size
- Regarding choices about prey-dropping
- How are all these estimates made?
o Height-breakage relationship
o Cost to break whelks of different sizes
Food Searching
- Advantage: perceptual screening mechanism that improves ability to locate specific food
items
- Cost: could reduce ability to detect other prey types
- Remembering how the prey looks like and capturing it
- Example: my book vs roommate’s book (different edition)
o Familiar and able to recognize my own book
o Difficult to identify my roommates book because different edition – color of
textbook is different
Jumping spiders
- Scytodid, pholcid, fly
- Pre-exposed with each and then given each
- The ones that were exposed early, ate more of those group
o This shows that they are using search image mechanism to recognize the prey that
were exposed beforehand
o Apparatus for studying prey
▪ Fully closed
▪ Partially closed
▪ Walks around when hunting for food
▪ When seeing prey – it will move towards prey slow
- Next test: freely visible prey
o Detection rate increases in scyodid and pholcid
▪ There is no benefit for search image – no need to detect because you can
see it!
▪ Its freely visible so that’s why all the preys are equally detected except fly
since that’s not preferred prey type
- Next test: partially obscured prey
o Detection rate increases based on the pre exposed group
▪ Ex: pre-exposed to scytodid then increase detection in scytodid etc for
pholcid and fly
Summary:
- Search image in spiders eating spider
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
How are all these estimates made: height-breakage relationship, cost to break whelks of different sizes. Advantage: perceptual screening mechanism that improves ability to locate specific food items. Cost: could reduce ability to detect other prey types. Remembering how the prey looks like and capturing it. Example: my book vs roommate"s book (different edition: familiar and able to recognize my own book, difficult to identify my roommates book because different edition color of textbook is different. Pre-exposed with each and then given each. Next test: freely visible prey: detection rate increases in scyodid and pholcid, there is no benefit for search image no need to detect because you can see it! Its freely visible so that"s why all the preys are equally detected except fly since that"s not preferred prey type. Next test: partially obscured prey: detection rate increases based on the pre exposed group, ex: pre-exposed to scytodid then increase detection in scytodid etc for pholcid and fly.
