© 2014 Pearson Education, Inc. Chapter 15 Animals of the Benthic Environment Rocky and sandy shores Coral Reef Deep Sea

© 2014 Pearson Education, Inc. Animals of the Benthic Environment- Overview Benthic communities include a variety of habitats. Corals need specific environmental conditions. Hydrothermal vents support diverse communities that rely on chemosynthesis.

© 2014 Pearson Education, Inc. What Communities Exist on the Deep-Ocean Floor? We do not know as much about deep-ocean floor communities as we do shallower water communities. –Expensive to explore the deep –Limited oxygen –Robotic technology for exploration

© 2014 Pearson Education, Inc. Deep Ocean Physical Environment Bathal, abyssal, hadal zones Light absent below 1000 meters (3300 feet) Temperature usually between −1.8°C (28.8°F) and 3°C (37°F) Pressure exceeds 200 atmospheres. Thin layer of sediment of clay or oozes High oxygen content of the water

© 2014 Pearson Education, Inc. Deep Ocean Physical Environment Abyssal storms –Affect bottom currents –Created by warm and cold core eddies of surface currents –Can last weeks

© 2014 Pearson Education, Inc. Deep Ocean Food Sources and Species Diversity No primary productivity Only 1–3% of euphotic food present Special adaptations for detecting food Species diversity equivalent to rain forest

© 2014 Pearson Education, Inc. Deep-Sea Hydrothermal Vent Biocommunities Discovery – Alvin in 1977 Galapagos Rift in Pacific Ocean Water temperature near vents 8–12°C (46–54°F) Temperature at the vents was 350°C (662°F) Chimney vents, hot acidic water

© 2014 Pearson Education, Inc. Deep-Sea Hydrothermal Vent Communities Hydrothermal vent biocommunities –Organisms previously unknown to science –Unusually large for depth in ocean Black smokers – underwater chimney vents emit sulfides

© 2014 Pearson Education, Inc. Locations of Hydrothermal Vent Communities

© 2014 Pearson Education, Inc. Hydrothermal Vent Species Giant tubeworms Giant clams Giant mussels Crabs Microbial mats Life supported by chemosynthesis – production of organic molecules from inorganic by using chemical energy released from compounds

© 2014 Pearson Education, Inc. Hydrothermal Vent Species Sulfur-oxidizing archea magnified 20,000 times. These archea live a symbiotic relationship with tubeworms, clams, and mussels of the hydrothermal vents.

© 2014 Pearson Education, Inc. Hydrothermal Vent Species

© 2014 Pearson Education, Inc. Chemosynthesis Microscopic archaea – thrive on hydrogen sulfide from vents – Manufacture sugar, carbon dioxide, and dissolved oxygen Base of hydrothermal vent food chain

© 2014 Pearson Education, Inc. Hydrothermal Vent Communities Vents active for years or decades Animal species similar at widely separated vents Larvae drift from site to site “Dead whale hypothesis” –Large carcasses may be stepping stone for larvae

© 2014 Pearson Education, Inc. Hydrothermal Vent Communities First Atlantic vents with biocommunities discovered in 1985 First Indian Ocean vent found in 2000 Vents differ in chemical and geological characteristics

© 2014 Pearson Education, Inc. Life Span of Hydrothermal Vents Vents controlled by sporadic volcanic activity Vent may be active for only years to decades Organisms die when vent is inactive Increased volcanic activity can kill organisms

© 2014 Pearson Education, Inc. Hydrothermal Vents and the Origins of Life Life on Earth may have originated at hydrothermal vents. –Uniform conditions –Presence of archaea bacteria –Microbes with genes identical to those found in humans

© 2014 Pearson Education, Inc. Low-Temperature Seep Biocommunities Chemosynthetically support life Hypersaline seeps –High salinity –Florida Escarpment – seeping water from limestone fractures

© 2014 Pearson Education, Inc. Low-Temperature Seep Biocommunities Gulf of Mexico seep from limestone escarpment fractures Sulfide rich waters support diverse biocommunitiy

© 2014 Pearson Education, Inc. Low-Temperature Seep Biocommunities Hydrocarbon seeps –Oil and gas seeps –Hydrogen sulfide and/or methane Hydrocarbon seep biocommunities

© 2014 Pearson Education, Inc. Low-Temperature Seep Biocommunities Subduction zone seeps –Juan de Fuca plate –Folded sedimentary rocks –Methane

© 2014 Pearson Education, Inc. Beneath the Sea Floor A new frontier Deep biosphere –Exists within sea floor Microbes live in pore fluids Might represent much of Earth’s total biomass