Some Animals are more Equal than others

Question 1

Some animals are

Answer 1

more equal than others

Question 2

every habitat is made up of a

Answer 2

community
- populated with different species
- made up of different numbers

Question 3

in 1963 what happened

Answer 3

zoology professor, Robert Paine, pried a purple starfish off the rocks and threw it out into the bay

Question 4

Fred Smith and the Uni of Michigan.

Answer 4

Fred Smith- professor
- he asked his class why trees are green?

• even though the obvious answer is chlorophyll, he was asking more so about FOOD CHAINS

Question 5

producers, herbivores, and predators and the associated theory

Answer 5

producers- energy suppliers to whatever lives off them
herbivores- feed off the producers
predators- feed off herbivores
= idea at the time
- limiting 1 limits the other therefore with a decrease of the number of herbivores, there is a decrease in the number of predators, and whatnot

Question 6

issue with the associated theory

Answer 6

theory: each level was regulated by food availability
= this theory was flaws because it doesn’t explain why herbivores don’t simply grow to t he point where they eat ALL the leaves on a tree

= professor Smith discussed this with 2 colleagues
1) Nelson Hairston
2) Lawrence Slobdokin
=PRODUCED A NEW IDEA: number of herbivores must be controlled bottom-up and top-down

Question 7

green world hypothesis

Answer 7

the world is green because predators keep herbivores in check
- radical at the time; because nobody at the time thought that predators had any role in regulating ecosystems

• Robert Paine put this hypothesis to the test
  = 1 of Smith’s students

Question 8

Paine at the Pacific Ocean

Answer 8

identified all the species and then “who ate who”
- carnivores gastropods ate barnacles
- sea urchins ate algae
= LOTS OF PATTERN

Question 9

Paine observation

Answer 9

species of large purple/orange starfish [pisaster ochraceus] was at the top of the food chain
- you have to surprise and pry the starfish grip from the victim
- starfish eat lots of mussels as well

Question 10

Paine asked

Answer 10

What happens when you remove the predator starfish from a single outcrop

= ecosystem changes rapidly

= within a year and a 1/2= ecological gold
- top predator had been removed
- number of species had decreased from 15-8

= after 3 yrs, the number of species went down to 7

= by 7 yrs, simplified to a monoculture (mussels)

Question 11

what happened to mussels over time

Answer 11

began to advance down the rock face and monopolized all the available space and pushed all other species out

Question 12

Paines discovery

Answer 12

• Paines Discovery: one predator can regulate the composition of an entire community
  = remove predator: ecosystem, simplifies itself

Question 13

Pained coined a term

Answer 13

KEYSTONE SPECIES
- the power 1 species can exert on an ecosystem
- once you remove the keystone the entire arch is broken down

Question 14

T/F: most species don’t have as big of an impact

Answer 14

T

Question 15

T/F: some tide pools had more urchins than others

Answer 15

T
- tide pools with more urchin had less kelp

• Paine suggested the urchins kept the kelp from growing
• he removed all the urchins in some pools and left others untouched
  (removing urchins: Kelp started growing immediately: violation of green world hypothesis)

violation bc- suggests that herbivore populations are controlled by predators, preventing them from overgrazing plants

Question 16

The urchins ate all the kelp…so what regulated the urchins?

Answer 16

• remote island in Alaskas Aleutian Island Chain
• Paine crossed paths with James Estes (grad student) in 1971

Question 17

James Estes

Answer 17

• studied sea otter physiology

= wanted to understand how an ecosystem could support an abundance of predators via production an efficiency of material flow

• ## Paine wanted James to see what otters were doing from TOP DOWN rather than kelp from the BOTTOM UP, he might discover the roles of otters in the organization of nature
• wanted to remove them to see the effects

Question 18

change in otter population over time (pre-experiment)

Answer 18

otters were abundant across the North Pacific and then the Pacific Maritime fur trade began in 1741
- over 150 years, otters were hunted to the brink of extinction
- in 1911 or 1912, fur trade was prohibited and a few colonies survived
= recovered across Aleutian archipelago

Question 19

Experiment

otters

Answer 19

compare ecosystems with otters to those without

*AMCHITKA (home island) have sea urchins and common+small

*SHEMYA - no otters, all urchins and no kelp

• w/o otters, low kelp, and high urchins
• DEMONSTRATION OF: green world hypothesis
• otters controlled urchins that feed on kelp
• w/o otters, urchins ate so many kelp

Question 20

trophic cascade

Answer 20

• cascading effects of 1 species down to another
• when an apex predator controls the distributing of resources which leads to cascades of indirect effects

sea otters = keystone species

Question 21

When Estes returned 20 years later

Answer 21

• otter population decreased
• rules out starvation and disease

Question 22

What did Tim Tinker hypothesize

Answer 22

(once they saw otter population decrease after 20 years)

• he was a technician who said orcas might’ve been eating otters
• they went to Clam Lagoon because orcas couldn’t get there
  = abundance of otters

Question 23

Why were orcas NOW eating otters

Answer 23

• they usually eat whales
• lots of whales after WW2 but then the Japanese and Russians started whaling and by the late 60s, the population decreased 90%
• this forced orcas to find new prey and they found otters
  = ORCAS ADDING A 4TH TROPHIC LEVEL

Question 24

W/ ORCAS

Answer 24

increased orcas

decreased otters

increased urchins

decreased kelp (disappeared)