Transcript Animals of the Benthic Environment

CHAPTER 15
Animals of the Benthic Environment
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Communities on Rocky Shores
• Species are
– Attached to bottom
– Move over seafloor (e.g., crabs, snails)
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Rocky Intertidal Zonation
Rocky shore:
• Spray and High tide
zones
• Middle tide zone
• Low tide zone
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Spray and Upper Tide Zone
• Harsh-few organisms
• Large Temp/Salinity
Changes
• Both Marine and Land
Predators
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Middle tide zone
Transition zone
– More Species
Diversity
– More Organisms
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Low tide zone
Life is easy here!
• Stable temp/salinity
• Lots of Species
Diversity
• Space limited
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Sandy Beach
• No stable, fixed surface
• Burrowing provides more stable
environment
– Less risk of temperature extremes and
drying out
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Sandy Beach
Burrowing
• Mollusks
– Soft body, hard shell
– Example: clams and
mussels
• Worms (annelids)
• Sand Crabs
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Shallow Offshore Communities
Rocky Bottoms
Kelp and kelp forests
– Attaches to rocky bottoms
– Can grow up to 0.6 meters
(2 feet) per day
– Provides shelter for other
organisms
– Rich ecosystems
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Kelp Distribution
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Coral Reefs
Shallow water
Tropical
Warm, clear, shallow
water
Polyps – individual
corals
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Coral Reef Distribution
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Coral Reef Zonation
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Importance of Coral Reefs
• Largest structures created by living
organisms
– Great Barrier Reef, Australia, more than
1250 miles long
• Great diversity of species
• Reefs protect shorelines and freshwater
supplies
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Coral Reefs in Decline
• 30% healthy today, 41% healthy in 2000
• Threats
– Hurricanes
– Coral bleaching
– Floods
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Deep-Ocean Floor Communities
•Hydrothermal Vents
•Light absent below 3300 feet
•Temperature usually 28°F to 37°F
•High pressure
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Locations of Hydrothermal Vent
Communities
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Chemosynthesis
• Microscopic organisms – thrive on hydrogen
sulfide from vents
– Manufacture sugar, carbon dioxide, and dissolved
oxygen
• Base of hydrothermal vent food chain
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Hydrothermal Vent Species
Life supported by chemosynthesis
• Giant tubeworms
• Giant clams
• Giant mussels
• Crabs
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Hydrothermal Vent
Communities
• Vents active for years
or decades
• Animals species
similar at widely
separated vents
• Larvae drift from site
to site
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