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A square piece of dry paper cannot be folded
in half more than 7 times
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Our eyes are always the same size from birth
14 - 1
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Objective: I will know what a keystone species is!
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Agenda:
1. Keystone notes
2. Chapter 14 vocab. (vocab as a class)
3. Urchin virtual lab info and clips
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Homework: Know the parts of a sea urchin.
Explore the anatomy link on this website:
http://virtualurchin.stanford.edu/
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If that species is removed there are
dramatic changes in and population
densities of all the other species in the
community.
Keystone species are usually predators
No comparable changes appear when
other species are removed from the
ecosystem.
14 - 4

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Kelp forests along the Pacific coast.
30 – 40 m water depth
 Determined by light availability

Found almost exclusively at areas of
upwelling
 Require high nutrient concentrations

Water temperatures cooler than 20oc
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Gas – containing sacs
to keep them buoyant
Grow as much as 50
cm a day
Continue to grow
once they reach the
surface
Supports diverse
community
Provide
 Food
 Protection/ hiding place
from predators
 Substrate/ habitat
kelp
provides
habitat
for otter
otters eat
sea urchins
sea urchins
eat kelp
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A ‘keystone’ predator
Sea urchins graze kelp beds
Otters keep sea urchin populations under
pressure
 Keep the sea urchin populations from growing too
large and destroying the kelp.

What happens if you remove the otters?
 Intensive hunting of otters in 1800s led decline of
kelp forests.
Chapter 14

Ecology is the science that studies how organisms
relate to each other and their environment.
Ecology and Ecosystems
 it embraces a wide range of disciplines:
 biology, physics, geology, climatology, oceanography,
paleontology, and astronomy
 ecology considers biotic (living) and abiotic (nonliving) factors
▪ abiotic includes:
- temperature, wind, pH, currents, minerals and sunlight
▪ biotic includes:
- the quantity and type of organisms in an environment
>

ecosystem
 a distinct entity, with …..
Ecology and Ecosystems

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clearly defined physical boundaries
distinct abiotic conditions
an energy source, and …
a community of interacting organisms
through which energy is transferred
community
 a collection of different organisms living
in an ecosystem
 includes all species and types of
organisms
>
14 - 15

population
 a group of the same species living and
interacting within a community

habitat
 includes the area and conditions in which
you find an organism
Ecology and Ecosystems

microhabitat
 exists on a very small scale; tiny worms
living between sand grains on the seafloor

niche
 an organism’s role in its habitat
 very different species can occupy the
same niche
>
14 - 16